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]]>Materials and Methods: This study had local Ethics Committee approval; all patients gave informed consent. Patients who underwent bypass surgery were excluded; patients with coronary artery stent-grafts were included. One hundred patients (20 women, 80 men; mean age, 62 years ± 10 [standard deviation]) known to have or suspected of having coronary artery disease underwent dual-source CT and invasive coronary angiography. Image quality was assessed. Accuracy of dual-source CT in depiction or exclusion of significant stenosis (≥50%) was evaluated on a per-segment and per-patient basis. Effects of heart rate, heart rate variability, and calcification on image quality and accuracy were analyzed by using multivariate regression and were analyzed between subgroups of predictor variables. Simple regression was performed to calculate thresholds for adequate image quality.
Results: Mean heart rate was 64.9 beats per minute ± 13.2, mean variability was 23.6 beats per CT examination ± 36.2, and mean Agatston score was 786.5 ± 965.9. Diagnostic image quality was obtained in 90.2% of segments. Sensitivity, specificity, and positive and negative predictive values for the presence of significant stenosis were, respectively, 91.1%, 92.0%, 75.4%, and 97.5% by segment and 100%, 81.5%, 93.6%, and 100% by patient. Image quality was significantly related to heart rate variability (P = .015) and calcification (P < .001); the number of nondiagnostic segments was significantly affected by calcification only. Calcification was the single factor with significant impact on diagnostic accuracy (P = .001).
Conclusion: While dual-source CT resulted in heart-rate independent image quality, image quality remained prone to heart rate variability and calcification.
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]]>Materials and Methods: The human research committee approved this HIPAA-compliant study and waived informed consent. Seventy-five patients had undergone 64-section coronary CT angiography: 25 were injected by using a monophasic, contrast-medium-only protocol with a single-syringe injector; 25 were injected by using a biphasic protocol with a dual-syringe injector; and 25 were injected by using a split-bolus protocol with a dual-syringe injector and an initial bolus of contrast medium followed by 50 mL of a 70%:30% saline-to–contrast medium mixture and a 30-mL saline chaser. Two radiologists rated the visualization of right and left heart structures and the degree of streak artifacts. One observer performed attenuation measurements of the cardiac chambers and of the coronary arteries. Data were analyzed with one-way analysis of variance and Duncan post-hoc multiple comparison procedures.
Results: Data for 27 women and 48 men (mean age, 62 years) were included. Mean contrast medium attenuation in the right heart was significantly (P < .001) higher in the split-bolus group than in the biphasic injection group but was significantly (P < .001) lower than in the monophasic injection group. For the left heart and the coronary arteries, there were no significant differences among the three groups. Artifacts occurred less frequently (P < .001) in the biphasic and split-bolus groups than in the monophasic group. Visualization of right heart structures was rated significantly (P < .05) better in the split-bolus group than in the two other groups, while there was no difference for visualization of left heart structures.
Conclusion: Split-bolus injection provides sufficient attenuation for visualization of the right heart, while streak artifacts from high-attenuation contrast material can generally be avoided and arterial attenuation is maintained.
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]]>Materials and Methods: Predefined inclusion criteria were used to conduct a hand search of two sets of radiologic journal articles for studies on assessment of the diagnostic performance of imaging techniques. These two sets of articles formed independent derivation and validation record sets for developing and evaluating the search strategy. The sensitivity and positive predictive values (PPVs) of search terms from the derivation reference-standard set of records were used to select terms and develop two components of the search strategy. The first component was used to identify any study (from the imaging literature) in which diagnostic test performance was assessed. The second component was used to identify studies of any imaging modality. The two components were combined in the final search strategy. The sensitivity, specificity, and PPV of the search strategy in the derivation and validation record sets were calculated.
Results: The final search strategy had a sensitivity of 92.8%, a specificity of 58.5%, and a PPV of 25.1% for retrieval of the derivation set of records. Validation with an independent set of records gave a sensitivity of 91.9% (95% confidence interval [CI]: 87.1%, 95.1%), a specificity of 52.2% (95% CI: 49.2%, 55.2%), and a PPV of 25.1% (95% CI: 22.0%, 28.5%). Removal of irrelevant publication types further improved specificity and PPV in the validation set: to 77.6% (95% CI: 75.0%, 80.0%) and 40.9% (95% CI: 36.2%, 45.7%), respectively. The volume of imaging literature retrieved from MEDLINE by using the described search strategy has tripled since 1975.
Conclusion: A sensitive search strategy to identify studies of the diagnostic performance of any imaging test was developed and validated. The retrieval estimates of this strategy in MEDLINE are adequate to develop a register of studies.
Supplemental material:
© RSNA, 2008
]]>Materials and Methods: The institutional animal care and use committee approved the animal studies. In vivo and ex vivo studies were performed. In the in vivo study, 20 lumbar vertebrae from six swine were locally heated by using 1- or 2-cm active-tip internally cooled electrodes. In the ex vivo study, 12 fresh pig cadaver lumbar vertebrae were extracted from four swine, and spinal tumor models with or without cortical bone defect were created by stuffing a cavity with muscle tissue and locally heated by using a 1-cm active-tip internally cooled electrode. The temperature was monitored in the spinal canal and around the vertebral body during ablation. Mann-Whitney U test was used to indicate a significant difference between groups by using 1- and 2-cm active tip in the in vivo study and between groups with and without cortical defect in the ex vivo study.
Results: In the in vivo study in which 1- and 2-cm active-tip needles were used, the temperature in the spinal canal rose to 38.2°C ± 2.7 (standard deviation) and 45.5°C ± 6.2, respectively. The latter was significantly higher than the former (P < .001). In the ex vivo study in which tumor models with or without a cortical bone defect were used, the temperature in the spinal canal rose to 48.4°C ± 6.2 and 31.3°C ± 3.4, respectively. The former was significantly higher than the latter (P < .001).
Conclusion: For in vivo cases with a 2-cm active tip and ex vivo cases with a vertebral posterior bone defect, the temperature rose to over 45°C, potentially injuring the spinal cord and peripheral nerves.
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]]>Materials and Methods: This study was granted exempt status by the institutional review board and the animal care and use committee. Fractures simulating the CML were produced in distal femurs of 20 deceased fetal pigs. Twenty normal femurs served as control femurs. Femurs were imaged with a standard single-side–read 100-µm pixel sampling imaging plate (IP), a high-resolution dual-side–read 50-µm pixel sampling IP, and a high-detail screen-film imaging system. Eight tube current–time product settings (0.5–10.0 mAs) and two tube voltage selections (56 and 70 kVp) were employed. Two pediatric radiologists evaluated 920 images for fracture by using a five-point Likert scale. Area under the receiver operating characteristic curve (Az) values for the imaging systems were compared by using nonparametric 2 tests (all P < .05).
Results: For pooled rater data, performance of computed radiography was comparable to that of screen-film imaging, and superior performance (P = .04) was achieved with the more experienced rater. The Az value tended to increase as the tube current–time product setting was increased. Within each system, there was no significant difference in Az values for all images obtained at 56 and 70 kVp (dual-side–read IP, P = .63; single-side–read IP, P = .25; screen-film imaging system, P = .5). At 56 kVp, a dose reduction of up to 69% was achieved, and accuracy of computed radiography was comparable to that of screen-film imaging.
Conclusion: Findings in this study suggest that computed radiography can replace screen-film imaging in the detection of CMLs and may permit dose reduction.
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]]>Materials and Methods: Institutional animal care and use committee approval was obtained. Seventeen female rats with implanted human breast cancers underwent dynamic albumin-(Gd-DTPA)30–enhanced MR imaging followed by an initial dose of bevacizumab or saline (as a control). Treatment was continued every 3rd day, for a total of four doses at five possible dose levels: 0 mg bevacizumab (n = 4 [control rats]), 0.1 mg bevacizumab (n = 3), 0.25 mg bevacizumab (n = 2), 0.5 mg bevacizumab (n = 5), and 1.0 mg bevacizumab (n = 3). A second MR imaging examination was performed 24 hours after the initial dose to enable calculation of the acute change in MR imaging–assayed leakiness, or KPS. This acute change in KPS at MR imaging was correlated with tumor growth response for each cancer at the completion of the 11-day treatment course. For statistical analyses, an unpaired two-tailed t test, analysis of variance, and linear regression analyses were used.
Results: The MR imaging–assayed change in tumor microvascular leakiness, tested as a potential biomarker, correlated strongly with tumor growth rate (R2 = 0.74, P < .001). KPS and tumor growth decreased significantly in all bevacizumab-treated cancers compared with these values in control group cancers (P < .05).
Conclusion: The MR imaging–assayed acute change in vascular leakiness after a single dose of bevacizumab was an early, measurable predictive biomarker of tumor angiogenesis treatment response.
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]]>Materials and Methods: Spherical and lobulated pulmonary nodules 3–15 mm in diameter were placed in a commercially available lung phantom and scanned by using a 16-section computed tomographic (CT) scanner. Nodule volume (V) was determined by using the diameters of 27 spherical nodules and the mass and density values of 29 lobulated nodules measured by using the formulas V = (4/3)r3 (spherical nodules) and V = 1000 · (M/D) (lobulated nodules) as reference standards, where r is nodule radius; M, nodule mass; and D, wax density. Experiments were performed to evaluate seven reconstruction kernels and the independent effects of FOV and section thickness. Automated nodule volume measurements were performed by using computer-assisted volume measurement software. General linear regression models were used to examine the independent effects of each parameter, with percentage overestimation of volume as the dependent variable of interest.
Results: There was no substantial difference in the accuracy of volume estimations across the seven reconstruction kernels. The bone reconstruction kernel was deemed optimal on the basis of the results of a series of statistical analyses and other qualitative findings. Overall, volume accuracy was significantly associated (P < .0001) with larger reference standard–measured nodule diameter. There was substantial overestimation of the volumes of the 3–5-mm nodules measured by using the volume measurement software. Decreasing the FOV facilitated no significant improvement in the precision of lobulated nodule volume measurements. The accuracy of volume estimations—particularly those for small nodules—was significantly (P < .0001) affected by section thickness.
Conclusion: Substantial, highly variable overestimation of volume occurs with decreasing nodule diameter. A section thickness that enables the acquisition of at least three measurements along the z-axis should be used to measure the volumes of larger pulmonary nodules.
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]]>Materials and Methods: Institutional animal use and care committee approval was obtained. Thirty male rats made up four groups of rats with an injured left posterior tibial nerve (irreversible neurotmesis, reversible neurotmesis, severe axonotmesis, or moderate axonotmesis) and one control group. There were six rats in each group. Signal intensity changes were seen in the gastrocnemius muscle on the T2-weighted MR images. T2 values were also measured in vivo with the Carr-Purcell-Meiboom-Gill method. Gait function was assessed by calculating the print length factor (PLF). T2 ratios and PLFs on the injured side were compared with those on the unaffected side. Ratios of specific acquisition points within groups were compared by using repeated-measures analysis of variance. Comparisons across the five groups at each acquisition point were performed by using one-way analysis of variance with Scheffe post hoc testing. P < .05 indicated a significant difference.
Results: The more severe the nerve damage, the higher the signal intensity on T2-weighted MR images. There were significant differences in T2 ratios between the nerve injury groups and the control group (P < .05). Changes in T2 values and ratios depended on the degree of nerve injury. In the reversible neurotmesis group, T2 values and ratios began to decrease 28 days after surgery. In the severe and moderate axonotmesis groups, T2 values and ratios began to decrease 14 days after surgery. The starting point of functional recovery also depended on the degree of nerve injury.
Conclusion: The degree and prognosis of nerve injury can be evaluated by observing changes in signal intensity on T2-weighted images and the time course of T2 values and ratios.
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]]>Materials and Methods: Approval from institutional review board was obtained for this HIPAA-compliant retrospective study; informed consent was waived. The study included all patients (42 men, 52 women; mean age, 61 years) who underwent abdominal 64-detector CT within 2 months of MRCP and/or ERCP. All patients underwent portal venous phase intravenous contrast material–enhanced abdominal CT. Sixty-one patients underwent MRCP and 54 patients underwent ERCP (21 patients underwent both). Two radiologists, blinded to the reference standard, independently evaluated the CT images, including multiplanar and minimum intensity reformations, for biliary duct narrowing and choledocholithiasis. Standard of reference examinations were used to calculate sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV).
Results: Twenty-three (24%) of 94 patients had a biliary duct narrowing at reference examinations. For detecting biliary duct narrowing, observer 1 had a sensitivity of 78.2%, specificity of 100%, PPV of 100%, and NPV of 93.4% and observer 2 had a sensitivity of 69.6%, specificity of 100%, PPV of 100%, and NPV of 91.0%. In 18 (19%) of 94 patients, choledocholithiasis was detected at reference examinations. For detecting choledocholithiasis, observer 1 had a sensitivity of 77.8%, specificity of 96.1%, PPV of 82.4%, and NPV of 94.8% and observer 2 had a sensitivity of 72.2%, specificity of 96.1%, PPV of 81.2%, and NPV of 93.6%.
Conclusion: Portal venous phase multidetector CT images are highly specific and moderately sensitive for the detection of biliary duct narrowing and choledocholithiasis.
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]]>Materials and Methods: This study was institutional review board approved, and the requirement for informed consent was waived. The imaging, medical, and histopathologic data of 10 patients (seven women, three men; mean age, 38 years) with histopathologically proved adult HD and/or adult HG were reviewed. Two radiologists reviewed 10 transverse computed tomographic (CT) scans and five double-contrast barium enema radiographs in consensus for the presence or absence and the location of the transition zone. The transverse diameter ratio of the most dilated colonic segment proximal to the transition zone to the narrowed colonic segment distal to the transition zone (ie, transition zone ratio), and the longitudinal length of the transition zone were also determined. The CT findings of HD and HG were compared by using the Mann-Whitney U test.
Results: All patients with lifelong or chronic constipation had a transition zone in the upper part of the rectum or rectosigmoid junction (n = 5) or in the descending colon (n = 5) on the CT scans and the double-contrast barium enema radiographs. The transition zone ratio was significantly different between the patients with HD (median ratio, 4.0) and the patients with HG (median ratio, 2.0) (P = .016). However, there was no significant difference in the longitudinal length of the transition zone between the two patient groups (median ratios, 4.4 cm for HD group and 6.0 cm for HG group; P = .190).
Conclusion: A markedly dilated proximal colonic segment with a transition zone and a narrowed distal colonic segment on CT and double-contrast barium enema images in conjunction with chronic refractory constipation in an adult should suggest the diagnosis of adult HD or adult HG. The detection of a much higher transition zone ratio may help to establish the diagnosis of HD.
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]]>Materials and Methods: Investigational review board approval was obtained, and the informed consent requirement was waived. The medical and imaging data of 21 patients (13 men, eight women; mean age, 47.5 years; age range, 25–79 years) with histopathologically proved AIP who underwent contrast material–enhanced CT at diagnosis and after steroid treatment were included in this study. Image analysis included assessment of the (a) presence or absence and type (focal or diffuse) of pancreatic parenchyma enlargement, (b) contrast enhancement of pancreatic parenchyma, (c) size of the main pancreatic duct (MPD) within the lesion and upstream, and (d) pancreatic parenchyma thickness in the head, body, and tail of the pancreas. The same criteria were applied to follow-up CT examinations, the follow-up data were compared with pretreatment data, and a paired sample t test was applied.
Results: Pancreatic parenchyma showed focal enlargement in 14 (67%) patients and diffuse enlargement in seven (33%). Pancreatic parenchyma affected by AIP appeared hypoattenuating in 19 (90%) patients and isoattenuating in two (10%). During the portal venous phase, pancreatic parenchyma showed contrast material retention in 18 (86%) patients and contrast material washout in three (14%). The MPD was never visible within the lesion. After treatment, there was a reduction in the size of pancreatic parenchyma segments affected by AIP (P < .05). Fifteen (71%) of the 21 patients had a normal enhancement pattern in the pancreatic parenchyma, whereas the enhancement pattern remained hypovascular in six (29%). The MPD returned to its normal size within the lesion in all patients at follow-up CT. In one of the eight patients with focal forms of AIP, the upstream MPD remained dilated.
Conclusion: AIP appeared as pancreatic parenchyma enlargement, with MPD stenosis within the lesion and upstream dilatation in focal forms of AIP. After steroid treatment, there was normalization of these findings.
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]]>Materials and Methods: Committee on Human Research approval was obtained and compliance with HIPAA regulations was observed, with waiver of requirement for written consent. Ninety-two men (mean age, 64 years; range, 43–85 years) were retrospectively identified who had biopsy-proved prostate cancer, who had undergone baseline endorectal MR imaging and MR spectroscopic imaging, and who had selected active surveillance for management. Their mean baseline serum prostate-specific antigen (PSA) level was 5.5 ng/mL, and the median Gleason score was 6. Two readers with 10 and 3 years of experience independently reviewed all MR images and determined whether tumor was apparent on the basis of evaluation of established morphologic and metabolic findings. Another investigator compiled data about baseline clinical stage, biopsy findings, and serum PSA measurements. Multiple logistic regression analysis was used to investigate the relationship between the clinical parameters and tumor apparency at MR imaging and the biochemical outcome.
Results: At baseline MR imaging, readers 1 and 2 considered 54 and 26 patients, respectively, to have inapparent tumor (fair interobserver agreement; = 0.30). During a mean follow-up of 4.8 years, 52 patients had a stable PSA level and 40 had an increasing PSA level. In multivariate analysis, no significant association was found between the baseline clinical stage, Gleason score, serum PSA level, or the presence of apparent tumor at endorectal MR imaging and MR spectroscopic imaging for either reader and the biochemical outcome (P > .05 for all).
Conclusion: Endorectal MR imaging and MR spectroscopic imaging findings of tumor apparency or inapparency in prostate cancer patients who select active surveillance for management do not appear to be of prognostic value.
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]]>Materials and Methods: This HIPAA-compliant study received institutional review board approval. All patients included had previously consented to the use of their medical records for research purposes. Eleven of 110 patients (10 men, one woman; mean age, 73.5 years) who underwent MR urography were ultimately identified to have 23 upper-tract urothelial carcinomas smaller than 2 cm or carcinoma in situ. Breath-hold coronal T2-weighted single-shot fast spin-echo and breath-hold coronal 3D T1-weighted spoiled GRE images with fat suppression during nephrographic and excretory phases after intravenous injection of gadolinium-based contrast material were obtained in all patients with a 1.5-T imager. Two radiologists reviewed the MR images in consensus for the presence of tumors. Lesion detectability was compared between each sequence by using the McNemar test.
Results: Of 23 tumors, 17 (74%) were detected by using at least one sequence, eight (35%) were detected with T2-weighted imaging, 15 (65%) were detected on nephrographic phase images, and 15 (65%) were detected on excretory phase images. Two lesions each were detected only on either nephrographic or excretory phase images. Detectability was significantly higher on nephrographic and excretory phase images compared with T2-weighted images (P < .05).
Conclusion: Gadolinium-enhanced 3D spoiled GRE MR urography helped detect 74% of small urothelial carcinomas. Nephrographic and excretory phase images are essential for helping detect small urothelial carcinomas.
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]]>Materials and Methods: The institutional review board waived the requirement for informed consent for this retrospective HIPAA-compliant study. The data of 25 consecutive patients (15 men, 10 women; age range, 39–75 years) who underwent renal magnetic resonance (MR) imaging, including diffusion-weighted imaging, before nephrectomy were included. Renal MR examinations were performed by using transverse T1-weighted dual-echo in-phase and out-of-phase sequences and transverse and coronal T2-weighted single-shot fast spin-echo sequences. Three-dimensional fat-saturated T1-weighted dynamic gadopentetate dimeglumine–enhanced sequences also were performed. Precontrast single-shot spin-echo echo-planar diffusion-weighted images were obtained with b values of 0, 500, and 1000 sec/mm2 at 1.5 T. Regions of interest were placed on renal lesions to measure the ADC of whole lesions, enhancing viable soft tissue, and nonenhancing necrotic or cystic areas. The T1 signal characteristics of the renal lesions and necrotic or cystic areas were recorded. The Wilcoxon rank sum test was used to compare the median ADC values of the various types of lesions and areas.
Results: Twenty-six renal tumors were found in the 25 patients. Eight patients were found to have 11 benign cysts. Renal tumors had significantly lower ADCs (median, 189.3 x 10–3 mm2/sec; range, [102.0–262.0] x 10–3 mm2/sec) compared with benign cysts (median, 322.8 x 10–3 mm2/sec; range, [217.0–421.0] x 10–3 mm2/sec; P < .001). Solid enhancing tumors had significantly lower ADCs (median, 162.3 x 10–3 mm2/sec; range, [102.0–284.0] x 10–3 mm2/sec) compared with nonenhancing necrotic or cystic regions (median, 247.7 x 10–3 mm2/sec; range, [85.2–310.0] x 10–3 mm2/sec; P = .007). T1 hyperintense lesions had lower ADCs compared with their hypointense counterparts.
Conclusion: The T1 signal characteristics of a renal lesion appear to be related to the ADC of the lesion. ADC may be helpful in characterizing and differentiating renal masses.
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]]>Materials and Methods: This study was HIPAA compliant and approved by the institutional review board; all participants provided informed consent. Medical history, anthropometric measurements, and blood pressure (BP) values were obtained from 50 men and 50 women aged 18–25 years. Images of the common carotid arteries were acquired from three independent complete cardiac cycles by using a 15L8-MHz US transducer. CIMT was measured on the images of each cycle that depicted the narrowest and widest vessel diameters, and at the R wave of the ECG. Measurements from the right and left carotid arteries were analyzed by using paired t tests; possible sex differences, by using unpaired t tests. Reproducibility was determined by using coefficients of variation and intraclass correlations (ICCs). Pearson correlations and multiple regression analyses were used to compare CIMT, body mass index (BMI), and BP.
Results: CIMT values were 7.2% and 7% greater in frames showing the narrowest lumen diameter and in R-wave ECG-triggered frames, respectively, than in those with the widest diameter. CIMT measurements were 2.2%–3.1% greater in the right carotid artery than in the left (P < .001) and were significantly related to BMI (r = 0.40, P < .001) and systolic BP (r = 0.34, P < .001). ICCs were stronger when assessments were obtained in three different cardiac cycles (0.92–0.98), rather than in one (0.79–0.91).
Conclusion: In healthy young adults, reproducibility of CIMT measurements is greatest when combining values from both carotid arteries and/or from the maximal and minimal arterial diameters.
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]]>Materials and Methods: The study was compliant with institutional and legislative requirements; donors had dedicated their body for education and research before death. Multidetector CT and DXA scans were acquired in 178 proximal femur specimens harvested from human cadavers (91 women, 87 men; mean age at death, 79 years ± 10.2; range, 52–100 years). An automated VOI-fitting algorithm was used to calculate BMD and bone mineral content (BMC) in the head, neck, and trochanter from CT findings and pixel distribution parameters. The femur failure load (FL) was determined by using a mechanical test. Quantitative CT BMD, quantitative CT pixel distribution parameters, DXA BMD, and FL were correlated at multiple regression analysis.
Results: Mean precision errors in quantitative CT BMD measurements at segmentation with repositioning were 0.56%, 2.26%, and 0.61% for the head, neck, and trochanter, respectively. For the head, neck, and trochanter, respectively, r values were 0.77, 0.53, and 0.59 for the correlation between quantitative CT BMD and FL and 0.74, 0.55, and 0.65 for the correlation between quantitative CT BMC and FL (P < .001). Values ranged from 0.77 to 0.80 for correlations between DXA BMD and FL and from 0.73 to 0.82 for correlations between DXA BMC and FL (P < .001). In a multiple regression model that included quantitative CT pixel distributions, adjusted multivariate correlation coefficient values for correlations with FL increased to up to 0.88.
Conclusion: Regional BMD of the proximal femur can be determined in vitro from quantitative CT data with high precision by using an automated VOI-fitting algorithm. The best multiple regression model for predicting FL included DXA BMD and regional quantitative CT BMD measurements.
© RSNA, 2008
Supplemental material:
Materials and Methods: Institutional review board approval and informed consent were obtained. Eleven healthy elderly (mean age, 64.0 years ± 6.4 [standard deviation]; six men, five women) and 17 healthy young volunteers (mean age, 30.3 years ± 6.5; seven men, 10 women) underwent muscle BOLD MR imaging of the calf. A fat-suppressed T2*-weighted single-shot multiecho echo-planar imaging sequence was used. Temporary vascular occlusion was induced with suprasystolic cuff compression of the thigh. T2* time courses of the muscle BOLD MR signal intensity were obtained from four calf muscles and were characterized by the following curve parameters: hyperemia peak value, time to peak, and T2* end value after 360 seconds of hyperemia. Differences in these parameters between the two cohorts were assessed by using a Student t test.
Results: Considerably lower T2* maxima were observed in the elderly group during hyperemia (P < .005), with a mean hyperemia peak value of 13.1% ± 3.0 compared with 18.9% ± 4.8 in young healthy adults. Peaking occurred earlier in the elderly group (P < .05), with a mean time to peak of 32.2 seconds ± 10.6 compared with 43.1 seconds ± 10.7 in young adults. Furthermore, the elderly group had a significantly slower decrease of the muscle BOLD signal after the hyperemia peak (P < .001), which led to a higher end value of 8.6% ± 3.0 compared with 2.6% ± 2.1 in the young group.
Conclusion: BOLD MR imaging results of the calf demonstrated statistically significant age-dependent differences in the rate, intensity, and recovery of the postocclusive muscle BOLD signal.
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]]>Materials and Methods: Approval for this retrospective HIPAA-compliant study was obtained from the Institutional Board of Research Associates, with waiver of informed consent. One hundred eighty-nine patients (122 male and 67 female patients; median age, 43 years; range, 4–80 years) were examined with dynamic susceptibility-weighted contrast material–enhanced perfusion magnetic resonance (MR) imaging and were followed up clinically with MR imaging (median follow-up, 334 days). Log-rank tests were used to evaluate the association between relative CBV and time to progression by using Kaplan-Meier curves. Binary logistic regression was used to determine whether age, sex, and relative CBV were associated with an adverse event (progressive disease or death).
Results: Values for the mean relative CBV for patients according to each clinical response were as follows: 1.41 ± 0.13 (standard deviation) for complete response (n = 4), 2.36 ± 1.78 for stable disease (n = 41), 4.84 ± 3.32 for progressive disease (n = 130), and 3.82 ± 1.93 for death (n = 14). Kaplan-Meier estimates of median time to progression in days indicated that patients with a relative CBV of less than 1.75 had a median time to progression of 3585 days, whereas patients with a relative CBV of more than 1.75 had a time to progression of 265 days. Age and relative CBV were also independent predictors for clinical outcome.
Conclusion: Dynamic susceptibility-weighted contrast-enhanced perfusion MR imaging can be used to predict median time to progression in patients with gliomas, independent of pathologic findings. Patients who have HGGs and LGGs with a high relative CBV (>1.75) have a significantly more rapid time to progression than do patients who have gliomas with a low relative CBV.
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]]>Materials and Methods: This HIPAA-compliant study had institutional review board approval, with waiver of informed consent. The authors evaluated the effect of dose modulation on four types of neuroradiologic CT studies: brain CT performed without contrast material (unenhanced CT) in adult patients, unenhanced brain CT in pediatric patients, adult cervical spine CT, and adult cervical and intracranial CT angiography. For each type of CT study, three series of 100 consecutive studies were reviewed: 100 studies performed without dose modulation, 100 studies performed with z-axis dose modulation, and 100 studies performed with x-y-z–axis dose modulation. For each examination, the weighted volume CT dose index (CTDIvol) and dose-length product (DLP) were recorded and noise was measured. Each study was also reviewed for image quality. Continuous variables (CTDIvol, DLP, noise) were compared by using t tests, and categorical variables (image quality) were compared by using Wilcoxon rank-sum tests.
Results: For unenhanced CT of adult brains, the CTDIvol and DLP, respectively, were reduced by 60.9% and 60.3%, respectively, by using z-axis dose modulation and by 50.4% and 22.4% by using x-y-z–axis dose modulation. Significant dose reductions (P < .001) were also observed for pediatric unenhanced brain CT, cervical spine CT, and adult cervical and intracranial CT angiography performed with each dose modulation technique. Image quality and noise were unaffected by the use of either dose modulation technique (P > .05).
Conclusion: Use of dose-modulation techniques for neuroradiology CT examinations affords significant dose reduction while image quality is maintained.
Supplemental material:
© RSNA, 2008
]]>Materials and Methods: Institutional review boards from two institutions approved the HIPAA-compliant study; all patients provided informed consent. One hundred thirty-seven patients underwent 225 administrations of 90Y microspheres by using intraarterial infusion. Primary sites (origins) included colon, breast, neuroendocrine, pancreas, lung, cholangiocarcinoma, melanoma, renal, esophageal, ovary, adenocarcinoma of unknown primary, lymphoma, gastric, duodenal, bladder, angiosarcoma, squamous cell carcinoma, thyroid, adrenal, and parotid. Patients underwent evaluation of baseline and follow-up liver function and tumor markers and computed tomographic or magnetic resonance imaging. Patients were observed for survival from first treatment. Median survival (in days) and corresponding 95% confidence intervals were computed by using the Kaplan-Meier method. The log-rank statistic was used for statistical significance testing of survival distributions between various subgroups of patients.
Results: There were 66 men and 71 women. All patients were treated on an outpatient basis. Median age was 61 years. The mean number of treatments was 1.6. The median activity and dose infused were 1.83 GBq and 112.8 Gy, respectively. Clinical toxicities included fatigue (56%), vague abdominal pain (26%), and nausea (23%). At follow-up imaging, according to World Health Organization criteria, there was a 42.8% response rate (2.1% complete response, 40.7% partial response). There was a biologic tumor response (any decrease in tumor size) of 87%. Overall median survival was 300 days. One-year survival was 47.8%, and 2-year survival was 30.9%. Median survival was 457 days for patients with colorectal tumors, 776 days for those with neuroendocrine tumors, and 207 days for those with noncolorectal, nonneuroendocrine tumors.
Conclusion:90Y hepatic treatments are well tolerated with acceptable toxicities; tumor response and median survival are promising.
Clinical trial registration no. NCT00532740.
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]]>Materials and Methods: One hundred ninety-five women, aged 18–44 years, with 200 fetal referrals for VM, were recruited in a prospective IRB-approved, HIPAA-compliant study. Written informed consent was obtained. US scans were prospectively interpreted by three obstetric radiologists and MR examinations were read by one obstetric radiologist and three pediatric neuroradiologists. Final diagnosis was reached by consensus (198 US, 198 MR, and 196 US-MR comparisons). Gestational age, ventricular size, types of disagreements, and reasons for disagreements were recorded. Interreader agreement was assessed with statistics. Ventricular diameter, gestational age, and confidence scores were analyzed by using mixed-model analysis of variance, accounting for correlation within reader and fetus.
Results: There was prospective agreement on 118 (60%) of 198 US and 104 (53%) of 198 MR readings. Consensus was more likely when the final diagnosis was isolated VM (83 of 104, 80% at US; 82 of 109, 75% at MR) than when the final diagnosis included other anomalies as well (14 of 63, 22% at US; seven of 68, 10% at MR; P < .001). There was disagreement on 19 (10%) of 196 and 31 (16%) of 196 fetuses about the presence of VM at US and MR, respectively, and on 29 (15%) of 198 and 39 (20%) of 198 fetuses regarding the presence of major findings at US and MR, respectively. Reasons for discrepancies in reporting major findings included errors of observation, lack of real-time US scanning, lack of neuroradiology experience, as well as modality differences in helping depict abnormalities.
Conclusion: Of radiologists who read high-risk obstetric US and fetal MR images for VM, there is considerable variability in central nervous system diagnosis.
© RSNA, 2008
]]>Materials and Methods: This HIPAA-compliant study was conducted with institutional review board approval and parental informed consent. The hospital sedation committee approved a 2-month pilot program of propofol sedation as a potential alternative to pentobarbital sedation. Parents were given the choice of having their child sedated with intravenously administered propofol or pentobarbital. Fifty-two patients (18 female, 34 male; mean age, 2.9 years ± 2.4 [standard deviation]) received propofol. An equal number of patients (21 female, 31 male; mean age, 2.5 years ± 1.7) who previously received pentobarbital were included. The sample sizes provided 80% power to detect differences in airway manipulations, adverse respiratory events, and recovery time between the groups by using the Fisher exact test and the Student t test. A two-tailed P value of less than .05 indicated a significant difference.
Results: Patients sedated with propofol underwent significantly more airway manipulations to relieve obstruction than did patients sedated with pentobarbital (23% vs 0%, P < .001). More adverse respiratory events occurred in the propofol group than in the pentobarbital group (12% vs 0%, P = .03). Patients in the propofol group had a faster recovery profile than did patients in the pentobarbital group (34 minutes ± 17 vs 100 minutes ± 30, P < .001).
Conclusion: Propofol is associated with a significantly greater incidence of adverse respiratory events than is pentobarbital.
© RSNA, 2008
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© RSNA, 2008
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]]>Materials and Methods: Institutional review board approval was obtained, and the informed consent requirement was waived for this HIPAA-compliant study. Retrospective analysis was performed with 27 consecutive patients (12 male, 15 female; age range, 16–67 years) who underwent MR venography of the central veins. Six radiologists with varying levels of experience interpreted the studies. For each study, the readers were presented with time-resolved maximum intensity projection (MIP) images only, high-spatial-resolution images only, or both. Sensitivity and specificity were calculated for detection of stenoses and occlusions, as well as for confidence levels, study interpretation time, and determination of the side of the body on which upper extremity contrast material injection was performed.
Results: The addition of time-resolved angiographic images to the high-spatial-resolution images resulted in improved specificity in the detection of venous occlusions (0.99 vs 0.96, P = .03), in reader confidence (P < .001), and in the ability to infer the side of injection (83% correct compared with 32% correct, P < .001), without increasing the average time required for study interpretation. Use of time-resolved angiographic data sets as a stand-alone technique had high sensitivity (0.95) but only moderate specificity (0.56) in the detection of venous stenoses or occlusions.
Conclusion: Time-resolved angiographic images are a useful adjunct to high-spatial-resolution images in the evaluation of central venous stenoses and occlusions.
© RSNA, 2008
]]>Materials and Methods: This HIPAA-compliant study was approved by the Institutional Review Board; informed consent was waived. Forty-three patients (17 men, 26 women; mean age, 46 years; age range, 10–89 years) with a total of 46 abscesses underwent percutaneous drainage with 8.5–14-F catheters. Etiology was postoperative in 28 abscesses (60.9%) and varied in 18 (39.1%). Intracavitary tPA was initiated on the basis of viscous contents yielding minimal drainage at initial placement or if follow-up imaging showed a large residual collection despite satisfactory catheter position. A treatment cycle was 4–6 mg of tPA in 0.9% saline administered twice daily for 3 days. Drainage success was defined as evacuation of the abscess without surgery. Safety was evaluated on the basis of complications. Statistical analysis was performed by using the Student t test and Fisher exact test.
Results: Forty-six abscesses were initially drained by 51 catheters. Complete evacuation was achieved in 41 (89.1%) abscesses, whereas five (10.9%) required surgical drainage. Three (60%) of these five had a documented fistula, a higher (P = .02) percentage than in successfully drained abscesses. Three (6.5%) of the 46 abscesses recurred (12–95 days after catheter removal). There were no tPA-linked bleeding complications despite four patients receiving full systemic anticoagulation and 24 receiving prophylactic anticoagulation.
Conclusion: Intracavitary tPA is safe and effective for draining complex fluid collections, with most patients avoiding surgery.
© RSNA, 2008
]]>Materials and Methods: The study protocol was approved by the institutional ethics committee, and informed consent was obtained from each patient. Patients from one institution who had dysphagia caused by inoperable esophageal cancer were randomly assigned to receive treatment with a stent loaded with 125I seeds (irradiation stent group) or a conventional covered stent (control group). After stent implantation, the outcomes were measured in terms of relief of dysphagia, survival time, and complications related to the procedure. Dysphagia was assigned a grade. A P value of less than .05 was considered to indicate a significant difference.
Results: The stent was successfully placed in the diseased esophagus in all 53 patients (27 patients in the irradiation stent group and 26 patients in the control group). The dysphagia grades significantly improved in both groups within the 1st month after stent placement but were better in the irradiation stent group than in the control group after 2 months (P < .05). The median and mean survival times were better in the irradiation stent group than in the control group, and the differences were significant (P < .001). Hemorrhage occurred in 16 (30%) patients in both groups combined during follow-up.
Conclusion: In patients with advanced esophageal cancer, treatment with an esophageal stent loaded with 125I seeds, compared with that with a conventional covered stent, has potential benefit in that it allows a slightly longer relief of dysphagia and extended survival.
© RSNA, 2008
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