Materials and Methods: The study was approved by the institutional review board, and informed consent was obtained from all patients. In 40 patients (27 women, 13 men; age range, 33–94 years; mean age, 62.5 years) in whom colorectal cancer (n = 20) and breast cancer (n = 20) had metastasized to the liver, initial tumor volume and thermal-induced necrosis after MR-guided laser-induced thermotherapy were retrospectively analyzed. All patients presented with oligonodular liver metastases and underwent follow-up with contrast-enhanced MR imaging for at least 3 years. No concomitant oncologic therapies were performed.
Results: Volumetric MR imaging evaluation depicted 40 metastases with an initial tumor volume less than 5 mL (x = 1.75), nine metastases with initial volume of 5–20 mL (x = 12.35), and eight metastases with initial volume more than 20 mL (x = 50.57). The mean volume of the thermally damaged area was 498% of the initial volume for colorectal cancer metastases and 604% of the initial volume for breast cancer metastases. The ischemic and necrotic volume for colorectal cancer metastases had decreased by a mean of 48.6% after 3 months, by 63% after 6 months, by 70.2% after 12 months, and by 92.2% after 36 months. For breast cancer metastases at 36 months, the necrotic volume had decreased by 80.61%; the reduction in the volume of the thermally damaged region was statistically significantly lower than that of colorectal cancer metastases.
Conclusion: MR-guided laser-induced thermotherapy induced a high volume of thermal ablation; the greatest reduction in the necrotic volume occurred in the first year, and lower values were seen in the next period. The reduction was statistically significantly higher in colorectal cancer metastases.
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]]>Materials and Methods: Institutional review committee approval and patients' written informed consent were obtained. CT images of the abdomen were obtained by using 2 mL per kilogram of BW of intravenous contrast material (300 mg/mL iodine) injected at 4 mL/sec in 161 consecutive patients (age range, 28–90 years; mean age, 63 years; 95 men, 66 women). CT scans were initiated 45 and 150 seconds after aortic enhancement increased by 50 HU. The patients were divided into low (37–54 kg) and high (55–75 kg) BW groups. The HU/I, where HU is change in CT number and I is iodine dose in grams, and adjusted maximum hepatic enhancement (HU/[I/kg]) were assessed for correlation with BW, body mass index (BMI), and body fat percentage (BFP) by using linear regression.
Results: HU/I correlated (P < .001) inversely with BW in the aorta (r = –0.78) and liver (r = –0.80) and with BMI in the aorta (r = –0.59) and liver (r = –0.61) on portal venous phase images. Regression formula for the low BW group was HU/I = 4.1 – .044 · BW (P < .001) and for the high BW group was HU/I = 2.7 – .017 · BW (P < .001), suggesting that the amount of contrast material required with increased BW is less in the high BW group. Adjusted maximum hepatic enhancement directly correlated with BFP (r = 0.25, P < .01).
Conclusion: Excessive contrast material may inadvertently be given in heavier patients when the dose is determined by patient BW. Contrast material dose may need to be tailored in individual patients by using BFP.
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]]>Materials and Methods: This study received institutional review board approval and was HIPAA compliant. Informed consent was waived. Eight subjects (four men, four women; median age, 40 years; range, 35–57 years), all potential renal donors with no pancreatic pathologic abnormalities, underwent abdominal CT imaging, which resulted in 30 10-mm-thick sections obtained at a single level. Imaging was a direct result of bolus timing employed for standard renal donor protocol; no additional imaging beyond what was clinically warranted was performed. Images were obtained every 3 seconds; scanning was initiated at the onset of contrast material administration. Region-of-interest measurements were obtained for the pancreatic body and the aorta to generate time-enhancement curves (TECs). A one-compartment model was applied by using the aortic and pancreatic TECs as the input and output functions, respectively. Pancreatic volumetric blood flow FV, volume of distribution VD, and blood transit time were determined. Modeled pancreatic TECs were generated and were compared with actual TECs for wellness of fit.
Results: Pancreatic FV values from the single-compartment model ranged from 0.961 to 6.405 min–1 (mean, 3.560 min–1 ± 1.900 [standard deviation]). Volume of distribution VD ranged from 1.491 to 3.080 (mean, 2.383 ± 0.638), while values of ranged from –3.090 to 6.436 seconds (mean, 0.481 second ± 3.000). Modeled pancreatic TECs closely matched true pancreatic TECs for each subject, with R2 values ranging from 0.840 to 0.959.
Conclusion: A simple one-compartment kinetic model can be applied to contrast-enhanced images of normal pancreas to yield accurate pancreatic TECs, which attest to the perfusion parameters obtained. In addition to yielding volumetric blood flow similar to that of other models of tissue perfusion, two additional pancreatic perfusion parameters can be obtained.
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]]>Materials and Methods: This HIPAA-compliant study was approved by the institutional review board; informed consent was waived. Ninety-five patients (58 female, 37 male; mean age, 51 years; range, 15–91 years) underwent MRCP by using the respiratory-triggered isotropic 3D fast-recovery FSE sequence and endoscopic or percutaneous direct visualization between March 2003 and June 2007. Two independent readers evaluated the MRCP images for strictures, dilatation, and intraductal filling defects. Sensitivity, specificity, and interobserver agreement ( statistics) were determined.
Results: The respective sensitivity and specificity for strictures, dilatation, and intraductal filling defects (all choledocholithiasis) were 86% (40 of 47) and 94% (45 of 48), 98% (57 of 58) and 100% (37 of 37), and 68% (19 of 28) and 97% (65 of 67) for reader 1 and 88% (41 of 47) and 94% (45 of 48), 96% (56 of 58) and 100% (37 of 37), and 75% (21 of 28) and 99% (66 of 67) for reader 2. The sensitivity for stones larger than 3 mm was 94% (15 of 16) for reader 1 and 100% (16 of 16) for reader 2, whereas the sensitivity for stones 3 mm or smaller was 33% (four of 12) for reader 1 and 42% (five of 12) for reader 2. Agreement between readers was good to excellent, with values of 0.76, 0.85, and 0.98 for strictures, dilatation, and choledocholithiasis, respectively.
Conclusion: MRCP by using the respiratory-triggered isotropic 3D fast-recovery FSE sequence with parallel imaging demonstrates excellent diagnostic capabilities for possible biliary disease, although it is limited for stones 3 mm or smaller in size.
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]]>Materials and Methods: The institutional review board approved this retrospective study; informed consent was waived. IVIM DW imaging was tested on three alkane phantoms, on which the signal-intensity decay curves according to b factors were logarithmically plotted. Ten b factors (0, 10, 20, 30, 50, 80, 100, 200, 400, 800 sec/mm2) were used in patients. Patients with documented liver cirrhosis (cirrhotic liver group, n = 12) and patients without chronic liver disease (healthy liver group, n = 25) were included. The mean liver D, D*, and f values were measured and compared with the apparent diffusion coefficient (ADC) computed by using four b values (0, 200, 400, 800 sec/mm2). Liver ADC and D, f, and D* parameters were compared between the cirrhotic liver group and healthy liver group. Means were compared by using the Student t test.
Results: Signal-intensity decay curves were monoexponential on phantoms and biexponential in patients. In vivo, mean ADC values were significantly higher than D in the healthy liver group (ADC = 1.39 x 10–3 mm2/sec ± 0.2 [standard deviation] vs D = 1.10 x 10–3 mm2/sec ± 0.7) and in the cirrhotic liver group (ADC = 1.23 x 10–3 mm2/sec ± 0.4 vs D = 1.19 x 10–3 mm2/sec ± 0.5) (P = .03). ADC and D* were significantly reduced in the cirrhotic liver group compared with those in the healthy liver group (respective P values of .03 and .008).
Conclusion: Restricted diffusion observed in patients with cirrhosis may be related to D* variations, which reflect decreased perfusion, as well as alterations in pure molecular water diffusion in cirrhotic livers.
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]]>Materials and Methods: After institutional review board approval and informed patient consent were obtained for this prospective study, 23 patients (11 men, 12 women; mean age, 68.4 years; age range, 34.8–87.1 years) with colorectal adenocarcinoma underwent a 65-second perfusion CT examination, and tumor blood flow, blood volume, mean transit time, and permeability surface-area product were determined. After surgery, resected specimens were sectioned and stained immunohistochemically to identify CD34 for quantification of microvessel density (MVD), to identify smooth muscle actin for assessment of pericyte coverage index, to identify vascular endothelial growth factor (VEGF), and to identify glucose transporter protein (GLUT-1). Perfusion CT measurements were correlated with MVD, pericyte coverage index, VEGF expression, and GLUT-1 expression by using Pearson or Spearman rank correlation analysis, with significance assigned at the 5% level.
Results: Mean blood flow, blood volume, transit time, and permeability surface-area product values were 72.1 mL/min/100 g of tissue ± 28.4 (standard deviation), 6.2 mL/100 g of tissue ± 1.4, 9.3 seconds ± 3.9, and 13.9 mL/min/100 g of tissue ± 3.2, respectively. Blood volume (r = 0.59, P = .002) and permeability surface-area product (r = 0.46, P = .03) correlated positively with MVD, but blood flow (r = 0.27, P = .22) and transit time (r = –0.18, P = .44) did not. There were no significant associations between any perfusion CT parameter and pericyte coverage index (r ≤ 0.36, P > .05), VEGF score ( ≤ 0.30, P ≥ .15), or GLUT-1 score ( < 0.21, P ≥ .33).
Conclusion: Tumor permeability surface-area product and blood volume correlate positively with MVD and may reflect the microvascularity of colorectal tumors.
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]]>Materials and Methods: The committee on human research approved this HIPAA-compliant study and waived written informed consent. Thirty-five consecutive patients {24 female [mean age, 38 years ± 19 (standard deviation); range, 1–67 years] and 11 male [mean age, 29 years ± 22; range, 2–61 years]} with a mean age of 35 years ± 20 (range, 1–67 years) who underwent liver transplantation for fulminant hepatic failure at our institution during a 5-year period were retrospectively identified. Pretransplant ultrasonographic (n = 38; three patients each had two studies) and computed tomographic (n = 2) studies were retrospectively and independently reviewed for hepatic surface nodularity. Liver explant histopathologic findings (n = 33; slides unavailable in two patients) were reviewed for cirrhosis and for the combination of alternating foci of confluent regenerative nodules and necrosis. Differences among patients with nodular versus smooth liver surfaces in the proportion with the two histopathologic findings were compared with Fisher exact test. Differences in illness duration and maximum liver biochemical indices were compared with Mann-Whitney Rank Sum test.
Results: Fifteen of 35 patients (43%) demonstrated hepatic surface nodularity at pretransplant imaging, none of whom had cirrhosis at histopathologic examination. One patient with a smooth liver surface had cirrhosis. Compared with those who had a smooth liver surface, patients with hepatic surface nodularity had a significantly greater proportion with the histopathologic finding of a combination of alternating foci of confluent regenerative nodules and necrosis (12 of 14 vs one of 19, P < .001), longer illness duration (31 days ± 32 vs 13 days ± 13, P = .029), and lower maximum liver biochemical indices.
Conclusion: Hepatic surface nodularity is commonly seen at imaging in fulminant hepatic failure and usually reflects a combination of alternating foci of confluent regenerative nodules and necrosis; this is important because an erroneous radiologic diagnosis of cirrhosis in this setting could adversely affect transplantation status.
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]]>Materials and Methods: Institutional review board approval was obtained for this retrospective case-control study of 96 subjects with laparotomy-confirmed findings: 54 consecutive patients with bowel and/or mesenteric injury (surgically important and unimportant) (32 male patients, 22 female patients; mean age, 40.4 years ± 17.6 [standard deviation]; range, 16–86 years) and 42 matched patients without bowel and/or mesenteric injury (22 male patients, 20 female patients; mean age, 36.8 years ± 20.1; range, 14–84 years) who underwent four-detector CT prior to surgery. A second-year radiology resident, an abdominal imaging fellow, and a staff abdominal radiologist, blinded to patient outcome, independently reviewed CT studies and recorded the probability of bowel and/or mesenteric injury on a five-point scale. Sensitivity and specificity were calculated for each reviewer, and areas under the receiver operating characteristic curve (AUCs) were compared.
Results: Thirty-eight (40%) of 96 patients had surgically important bowel and/or mesenteric injury, and 58 (60%) of 96 patients had either no or surgically unimportant bowel and/or mesenteric injury. Sensitivities of the three reviewers in the diagnosis of surgically important bowel and/or mesenteric injury ranged from 87% (33 of 38) to 95% (36 of 38); specificities ranged from 48% (28 of 58) to 84% (49 of 58). The only significantly better AUC belonged to the staff radiologist for surgically important mesenteric injury (P = .01). Bowel wall defect, extraluminal contrast material, thick large bowel, mesenteric vessel beading, abrupt termination of mesenteric vessels, and mesenteric vessel extravasation showed the best positive likelihood ratios for surgically important bowel and/or mesenteric injury; absence of peritoneal fluid showed the best negative likelihood ratio.
Conclusion: Multidetector CT findings accurately reveal surgically important bowel and/or mesenteric injury and have a high negative predictive value.
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]]>Materials and Methods: This HIPAA-compliant retrospective study was approved by the institutional review board. Informed consent was waived. Of 146 consecutive pregnant patients suspected of having appendicitis (mean age, 29 years) who underwent MR imaging, 143 had MR images in which the appendix and cecum were identifiable in the sagittal plane. Two observers reviewed the MR images; findings were agreed upon by consensus. With use of sagittal single-shot fast spin-echo MR images, the cecal tilt angle was calculated as the angle between the imaging table and a line drawn between the cecal tip and the luminal center of the most proximal inflection point in the ascending colon. The location of the appendiceal base relative to the lumbosacral spine was recorded. Statistical analyses were performed by using Spearman and Pearson correlation coefficients to evaluate the relationship among gestational age, appendiceal base location, and cecal tilt angle. Receiver operating characteristic curve analysis was performed to assess the ability of the cecal tilt angle to help differentiate between a high and low appendiceal base level.
Results: Cecal tilt angles showed moderate correlation with appendiceal base levels (Spearman correlation coefficient, 0.44; P < .001) and poor correlation with gestational age (Pearson correlation coefficient, 0.25; P = .002). Regardless of gestational age, cecal tilt angles of at least 90° were predictive of a high appendiceal base level with a specificity of 98% (95% confidence interval: 92%, 100%).
Conclusion: The cecal tilt angle is useful for localizing the appendix in pregnant patients at MR imaging and helps predict the location of the appendix within the right upper quadrant of the abdomen with high specificity, irrespective of gestational age.
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]]>Materials and Methods: This study had institutional review board approval, and informed consent was obtained from all patients. Dual-phase contrast material–enhanced CT was performed in 78 patients (48 men and 30 women; age, 34–91 years; mean age, 64.8 years) by using a 16-detector CT scanner. Patients were prospectively randomized into two equal-sized groups: those who underwent CT with 0.625-mm collimation and nonoverlapped reconstruction and those who underwent CT with 1.25-mm collimation and 50% overlapped reconstruction. Scan acquisition time was 7.5 seconds in both groups. CTDIvol was recorded. Arterial phase volume-rendered, arterial phase multiplanar reformatted, and portal venous phase multiplanar reformatted CT angiograms were generated. Qualitative assessment was performed for image quality and for depiction of splanchnic, intercostal, and lumbar arteries and veins. The unpaired t test was used for statistical comparison.
Results: On the arterial phase CT angiograms, there was no difference between the two collimation groups for the depiction of proximal splanchnic arteries, while the dorsal pancreatic, intercostal, and lumbar arteries and some peripheral splanchnic arterial branches were better delineated on CT scans obtained with 0.625-mm collimation than on scans obtained with 1.25-mm collimation (P < .05). Regarding the portal venous phase CT angiograms, no difference between the two groups was found in most veins, except the right adrenal vein (P = .003). Image quality was superior for 1.25-mm collimation (P < .001). CTDIvol values were positively correlated with patient body weight (r = 0.34, P < .001) but had no correlation with collimation size (P = .24).
Conclusion: Scanning with 1.25-mm collimation seems adequate for a routine CT angiography examination of most arteries and veins at 16-detector CT, while scanning with 0.625-mm collimation facilitates improved delineation of fine vessels. CTDIvol values correlate positively with body weight but have no correlation with collimation size.
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]]>Materials and Methods: This retrospective HIPAA-compliant study, which had institutional review board approval, evaluated extracolonic findings in 2195 consecutive asymptomatic adults (1199 women, 996 men; age range, 40–90 years; mean age, 58.0 years ± 8.1 [standard deviation]) undergoing low-dose CT colonographic screening performed without contrast material at a single institution over a 20-month period. All diagnostic workups generated because of extracolonic findings were reviewed. Associated costs were estimated by using 2006 Medicare average reimbursement. Testing for statistical significance was performed by using the 2 and t tests.
Results: Further diagnostic workup for unsuspected extracolonic findings was performed in 133 (6.1%) of 2195 patients, including 18 patients in whom additional workup was not recommended by the radiologist. Additional testing included ultrasonography (n = 64), CT (n = 59), magnetic resonance imaging (n = 11), other diagnostic imaging tests (n = 19), nonsurgical invasive procedures (n = 19), and surgical procedures (n = 22). Benign findings were confirmed in the majority of cases, but relevant new diagnoses were made in 55 (2.5%) patients, including extracolonic malignancies in nine patients. The mean cost per patient for nonsurgical procedures was $31.02 (95% confidence interval: $23.72, $38.94); that for surgical procedures was $67.54 (95% confidence interval: $38.62, $101.55).
Conclusion: Detection of relevant unsuspected extracolonic disease at CT colonographic screening is not rare, accounting for a relatively large percentage of cases in which additional workup was recommended. Judicious handling of potential extracolonic findings is warranted to balance the cost of additional workup against the potential for early detection of important disease, because many findings will prove to be of no clinical consequence.
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]]>Materials and Methods: Committee on Human Research approval and patient consent were obtained for this HIPAA-compliant study. Fifty-two patients (15 men, 37 women) with NAFLD (n = 29) or HCV and HIV–related liver disease (n = 23) underwent prospective contemporaneous MR imaging and liver biopsy. Liver SI loss was measured on opposed-phase T1-weighted and fat-suppressed T2-weighted MR images. Visceral fat area was measured at three levels on water-suppressed T1-weighted MR images (n = 44). Spearman rank correlation coefficients and recursive partitioning were used to examine correlations.
Results: Histopathologic liver steatosis correlated well with liver SI loss on opposed-phase T1-weighted MR images ( = 0.78), fat-suppressed T2-weighted MR images ( = 0.75), and average visceral fat area ( = 0.77) (all P < .01) but poorly with BMI ( = 0.53, P < .01). Liver SI losses on opposed-phase T1-weighted MR imaging of less than 3%, at least 3% but less than 35%, at least 35% but less than 49%, and at least 49% corresponded to histopathologic steatosis grades of 0 (n = 16 of 17), 1 (n = 11 of 16), 2 (n = 7 of 13), and 3 (n = 5 of 6), respectively. A visceral fat area of greater than or equal to 73.8 cm2 was associated with the presence of histopathologic steatosis in 41 of 44 patients.
Conclusion: Liver SI loss on opposed-phase T1-weighted MR images and visceral fat area may be used as biomarkers for the presence of liver steatosis and appear to be superior to BMI.
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]]>Materials and Methods: The study was institutional review board approved. Ten normal and 50 abnormal cases, those of 60 patients with 93 polyps—61 polyps 6–9 mm in diameter and 32 polyps 10 mm or larger—were selected from a previously published trial. Seven novice readers underwent initial training that consisted of a 1-day course, reading assignments, a self-study computer module (with 61 limited data sets), observation of an expert interpreting three cases, and full interpretation of 10 cases with unblinding after each case. After training, the observers independently interpreted 60 cases by means of primary two-dimensional reading with unblinding after each case. For each case, the reading time and the location and maximal diameter of the polyp(s) were recorded. A t test was used to evaluate the observers' improvements, and empirical receiver operating characteristic (ROC) curves were constructed.
Results: By-patient sensitivities and specificities were determined for each observer. The lowest by-patient sensitivity at the 6 mm or larger polyp threshold was 86%, with 90% specificity. Four observers had 100% by-patient sensitivity at the 10 mm or larger polyp threshold, with 82%–97% specificity. For polyps 10 mm or larger, mean sensitivity and specificity were 98% and 92%, respectively. For the last 20 cases, the average interpretation time per case was 25 minutes. The range of areas under the ROC curve across observers was low: 0.86–0.95.
Conclusion: In the described polyp-enriched cohort, novice CT colonographic data readers achieved high sensitivity and good specificity at formative evaluation of a comprehensive training program. Use of a similar comprehensive training method might reduce interreader variability in interpretation accuracy and be useful for reader certification.
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]]>Materials and Methods: An Institutional Review Board approved this study; informed consent was waived. Four radiologists without experience in CT colonography evaluated 100 optical colonoscopy–proved data sets of 100 patients (49 men, 51 women; mean age, 59 years ± 13 [standard deviation]; range, 21–85 years) by using the virtual dissection reading method. Two readers used concurrent CAD. Data sets were read during five consecutive 1-day sessions (20 data sets per session). Polyp detection and false-positive rates, receiver operating characteristics (ROCs), and reading times were calculated for individual, CAD group, and non-CAD group readings. Diagnostic values were compared by calculating the 95% confidence intervals (CIs) around the relative risk. Areas under ROC curves (AUCs) (Hanley and McNeil for paired analysis and z statistics for unpaired analysis) and reading times (Wilcoxon signed rank test) were compared across the sessions, within each session and for the whole study.
Results: The range of detection rates was 79 of 111 (.71 [95% CI: .61, .79]) to 91 of 111 (.82 [95% CI: .73, .88]). The range of false-positive rates was 17 of 111 (.15 [95% CI: .09, .23]) to 22 of 111 (.20 [95% CI: .12, .28]). All readers' AUCs rose from session 1 to session 4; this rise was significant (P < .05) for the non-CAD group. Only during session 1 was the CAD group AUC (.83) higher than the non-CAD group AUC (.54) (P < .05). Comparison of CAD and non-CAD reading times showed no significant difference for the whole study or during each session (P > .05).
Conclusion: The virtual dissection reading technique allows short learning curves, which may be improved by the concurrent use of CAD, without significant effect on average reading time.
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]]>Materials and Methods: The institutional review board approved this HIPAA-compliant study. Abdominal computed tomographic (CT) images of 38 consecutive patients with CF and a control group of 38 consecutive potential renal donors were retrospectively identified. Three readers independently recorded presence and location of colonic wall redundancy and wall thickness of the ascending, transverse, and descending colon. Interobserver agreement for colonic wall redundancy was determined with the statistic. Colonic wall thicknesses were compared between patient groups with the Student t test. Proportions of adult and pediatric patients with and those without colonic wall redundancy and prevalence of specific gene mutations were compared between groups with the Fisher exact test. CT findings were compared with radiologic reports and clinical records.
Results: Each reviewer found colonic wall redundancy in 11 of 28 adults with CF but in none of the children with CF (P < .05 for each reviewer). There was excellent interobserver agreement for identification of colonic wall redundancy ( = 0.91, P < .001). Mean thickness of the wall of the ascending colon was significantly greater in patients with CF who had colonic wall redundancy (4.0 mm) than in those without this finding (1.8 mm, P < .05) or in control patients (1.2 mm, P < .05). Among adult patients with CF, F508 mutation was the predominant mutant allele in 10 of 13 patients with normal colons at CT, whereas more uncommon non-F508 mutations were seen in seven of 10 patients with colonic wall redundancy (P < .05). Asymptomatic colonic wall redundancy at CT was prospectively misinterpreted as acute colonic disease in five adult patients.
Conclusion: Proximal colonic wall redundancy is seen frequently in adults with CF and may be more common in those with non-F508 CFTR gene mutations. This finding provides a starting point for further investigation of the molecular basis of colonic phenotype in CF.
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]]>Materials and Methods: The institutional review board approved this research and waived informed consent from the patients. Two radiologists blinded to the pathologic assessment of malignancy or parenchymal invasion of IPMN retrospectively evaluated CT images of 61 consecutive surgically resected tumors (26 adenomas, 15 noninvasive carcinomas, and 20 invasive carcinomas) in patients who underwent multiphase contrast material–enhanced CT with 0.5- or 1-mm collimation. The findings were statistically analyzed by using univariate and multivariate analyses, with the optimal cutoff levels of each continuous parameter determined by generating receiver operating characteristic curves.
Results: The following findings showed significant differences among the three groups: maximum diameter of the main pancreatic duct (MPD), size (length of major axis) of the largest mural nodule in the MPD or in any associated cystic lesion, abnormal attenuating area in the surrounding parenchyma, calcification in the lesion, protrusion of the MPD into the ampulla of Vater, and bile duct dilatation. An MPD diameter of 6 mm or larger, a mural nodule of 3 mm or larger, and an abnormal attenuating area were independently predictive of malignancy. A mural nodule of 6.3 mm or larger in the MPD and an abnormal attenuating area were independently predictive of parenchymal invasion. According to these criteria, the sensitivity, specificity, and accuracy for identifying malignancy were 83%, 81%, and 82% and for identifying parenchymal invasion were 90%, 88%, and 89%, respectively.
Conclusion: Multisection CT is useful for distinguishing among adenoma, noninvasive carcinoma, and invasive carcinoma in patients with IPMN.
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]]>Materials and Methods: Following approval from the Director of Professional Services, a retrospective review of radiography and of patient records was conducted for patients who presented to a nontrauma emergency department over a period of 6 months and who were imaged by using abdominal radiography. Only the first radiograph per patient was used for analysis. The interpretations were sorted as normal, nonspecific, or abnormal. The patients' medical records were reviewed to determine whether further imaging was performed (computed tomography, ultrasonography, or upper gastrointestinal imaging) and results were compared with abdominal radiography. Chart reviews were conducted to identify patients in whom abdominal radiography alone influenced treatment.
Results: In 874 patients, interpretation of abdominal radiography was normal in 34% (n = 300), nonspecific in 46% (n = 406), and abnormal in 19% (n = 168). Further imaging was performed for 50% (436) of all patients. Of 300 patients whose abdominal radiography results were normal, 42% (n = 125) had follow-up imaging; 72% (n = 90) of these showed abnormal, 78% (165 of 212) showed nonspecific, and 87% (86 of 99) showed abnormal findings. Of 438 patients who did not undergo follow-up imaging, 75% (n = 327) were discharged. For all indications other than catheter placement, abdominal radiography helped confirm the suspected diagnosis in 2%–8% of cases. In 37 (4%) of 874 patients, abdominal radiography was possibly helpful in changing patient treatment without a follow-up study.
Conclusion: Abdominal radiography is often requested; however, its results contribute to patient treatment in a small percentage of cases. With the exception of catheter placement, if a patient requires investigation beyond clinical history, physical examination, and lab results, the emergency physician should be encouraged to request more definitive imaging.
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]]>Materials and Methods: Institutional review board approval was obtained; all patients provided informed consent. Standard magnetic resonance (MR) imaging and diffusion-weighted (DW) MR imaging were performed before and 3, 7, and 42 days after initiating chemotherapy for 87 hepatic metastases in 23 colorectal and gastric cancer patients (16 men, seven women; mean age, 55.7 years; range, 33–71 years). Lesions were classified as either responding or nonresponding, according to changes in size at the end of therapy. Linear mixed-effects modeling was applied to analyze change in ADCs and size following treatment. The Pearson correlation test was calculated between those ADC parameters and tumor response.
Results: Thirty-eight responding and 49 nonresponding metastatic lesions were evaluated. Pretherapy mean ADCs in responding lesions were significantly lower than those of nonresponding lesions (P = .003). An early increase in ADCs (on day 3 or 7) was observed in responding lesions but not in nonresponding lesions (P = .002). Weak but significant correlations were found between final tumor size reduction and both pretreatment ADCs (P = .006) and early ADC changes (day 3, P = .004; day 7, P < .001).
Conclusion: ADC seems to be a promising tool for helping predict and monitor the early response to chemotherapy of hepatic metastases from colorectal and gastric carcinomas.
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]]>Materials and Methods: This HIPAA-compliant retrospective study received institutional review board approval, and written informed consent was obtained from 14 patients (mean age, 61 years ± 9 [standard deviation]; range, 41–78 years), including 10 men (mean age, 65 years ± 8; range, 47–78 years) and four women (mean age, 54 years ± 9; range, 41–59 years), with colorectal liver metastases. Magnetic resonance (MR) imaging was performed twice (first baseline MR image [B1] and second baseline MR image [B2]) in a single target lesion prior to therapy. Dynamic contrast material–enhanced MR imaging was performed by using a saturation-recovery fast gradient-echo sequence. A simplified contrast agent diffusion model was proposed, and a contrast agent diffusion coefficient (CDC) was calculated. The reproducibility of the CDC measurement was evaluated by using the Bland-Altman plot and a linear regression model.
Results: The mean CDC was 0.22 mm2/sec (range, 0.01–0.73 mm2/sec) on B1 and 0.24 mm2/sec (range, 0.01–0.71 mm2/sec) on B2, with an intraclass correlation coefficient of 0.91 (P < .0001). Bland-Altman plot showed good agreement, with a mean difference in measurement pairs of 0.017 mm2/sec ± 0.096. The slope from the linear regression model was 0.89 (95% confidence interval: 0.63, 1.15) and the intercept was 0.01 (95% confidence interval: –0.08, 0.09).
Conclusion: The CDC enables a quantitative description of contrast enhancement heterogeneity in lesions. Given the high reproducibility of the CDC metric, CDC appears promising for further qualification as an imaging biomarker of change measurement in response assessment.
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