| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Genitourinary Imaging |
1 From the Departments of Clinical Radiology (M.S., R.L.V., K.P., S.K., A.M.) and Urology (A.H., M.A.O.), Kuopio University Hospital, Finland. Received January 17, 2001; revision requested March 6; final revision received October 9; accepted October 26. Supported by Kuopio University Hospital (EVO funding no. 5063508), the Radiological Society of Finland, and the Pehr Oscar Klingendahl Fund. Address correspondence to M.S., North-Karelian Central Hospital, Department of Radiology, Tikkamäentie 16, 80210 Joensuu, Finland (e-mail: mazen.sudah@pkshp.fi).
 |
ABSTRACT |
|---|
 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
|---|
MATERIALS AND METHODS: Forty-nine patients underwent CT, MR urography (with T2-weighted and gadopentetate dimeglumine–enhanced T1-weighted sequences), and excretory urography. CT and MR urographic findings were evaluated separately and independently by two radiologists each (CT, observers A and B; MR urography, observers C and D) for the presence, cause, level, and degree of obstruction. The final conclusive diagnosis was based on the combination of excretory urographic, clinical, and interventional results.
RESULTS: At final diagnosis, 32 (65%) patients were found to have ureteral stones causing unilateral obstruction. In ureteral stone detection, the sensitivity and specificity of CT were 90.6% (29 of 32 patients) and 100.0% (17 of 17 patients), respectively (observer A) and 90.6% (29 of 32 patients) and 94.1% (16 of 17 patients), respectively (observer B), while those of MR urography were 93.8% (30 of 32 patients) and 100.0% (17 of 17 patients), respectively (observer C) and 100.0% (32 of 32 patients) and 100.0% (17 of 17 patients), respectively (observer D). Spearman correlation coefficients for stone size at CT were 0.76 (P < .001) and 0.75 (P < .001) and at MR urography, 0.49 (P = .005) and 0.51 (P = .004).
CONCLUSION: In routine clinical practice, CT is the modality of choice in the evaluation of patients with acute flank pain. MR urography is an accurate and suitable alternative imaging technique in selected patients.
© RSNA, 2002
Index terms: Computed tomography (CT), comparative studies • Computed tomography (CT), helical, 81.12115, 82.12115 • Genitourinary system, MR, 80.121411, 80.121412, 121413, 80.121415, 80.12149 • Magnetic resonance (MR), comparative studies • Ureter, calculi, 82.811 • Ureter, stenosis or obstruction, 82.811 • Urography, 80.1221
|
INTRODUCTION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
|---|
Magnetic resonance (MR) urography is a more recent imaging concept in evaluating the urinary tract. Investigators in several studies (10–16) have described the use of T2-weighted sequences in patients with various urologic abnormalities. T2-weighted sequences have been shown to be rapid, safe, and noninvasive for reliable depiction of urinary tract dilatation and level of obstruction. Nevertheless, the nondilated urinary tract is not visualized, and a tiny calculus may be hidden by the surrounding bright signal from urine (17). Nolte-Ernsting et al (18,19) described contrast material–enhanced excretory MR urography after low-dose diuretic injection and concluded that this technique is a promising and accurate alternative to excretory urography for imaging the morphology of the urinary tract. Since then, the authors of a few articles (20–23) have discussed the application of this technique.
The purpose of this study was to compare unenhanced helical CT and MR urography, by using T2-weighted and contrast-enhanced T1-weighted sequences, in examining patients with acute flank pain, with reference to excretory urography and the final clinical diagnosis.
|
MATERIALS AND METHODS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
|---|
Patients
During the study period, 55 patients with acute flank pain were referred for excretory urography. Three of these patients were excluded from the study. In the first patient, the obstruction resolved during MR urography, and a small distal ureteral stone passed into the urinary bladder and was confirmed with ultrasonography (US). In the second patient, MR urographic sequences were not performed in full because of equipment-related technical difficulties; and in the third patient, MR urography could not be performed because of the patient’s extreme obesity. In addition, three patients refused to participate in the study. Hence, 49 patients (10 women and 39 men; mean age, 52 years) underwent evaluation according to the study protocol, and 98 kidneys were examined. The mean serum creatinine level was 103 µmol/L (range, 71–158 µmol/L; normal range, 62–105 µmol/L). Before arrival at our hospital, the duration of symptoms was less than 72 hours in 41 (84%) patients, and eight patients had experienced intermittent symptoms during a period of 4–14 days. Nevertheless, all patients had acute flank pain symptoms during the 24 hours before presentation to the emergency department.
Imaging Methods
Helical CT.—Unenhanced helical CT was performed with a Somaton Plus-S scanner (Siemens, Erlangen, Germany). Two breath-hold clusters of approximately 25 seconds each were obtained, from the top of the kidneys to the bottom of the bladder. Collimation of 5 mm, pitch of 1.4, increment of 3 mm, 120 kV, 160 mA (in 40 patients), and 210 mA (nine patients with body mass index > 27) were used. No specific preparation was required. The total CT examination time was calculated starting with the beginning of acquisition of the first reference scan and ending at the acquisition of helical data.
MR urography.—MR imaging was performed with a delay of 15–30 minutes after CT, by using a 1.5-T scanner (Magnetom Vision; Siemens) with a phased-array body coil. Patients were asked to void before the MR urographic examination. Otherwise, no specific preparation was required, and no external compression was applied. Breath-hold sequences were used.
T2-weighted MR urography was performed with thin-section (fat-suppressed half-Fourier rapid acquisition with relaxation enhancement [RARE] imaging, with a repetition time msec/echo time msec of 11.90/95, 150° flip angle, 3–6-mm section thickness in coronal orientation, 240 x 256 matrix, and 15-second acquisition time) and thick-slab (fat-suppressed single-shot turbo spin-echo; 2,800/1,100, 150° flip angle, 40-mm slab thickness in coronal and sagittal orientations, 240 x 256 matrix, and 7-second acquisition time) acquisitions. Field of view was adjusted individually to accommodate different patient sizes. RARE imaging was also performed in transverse orientation (7–9-mm section thickness) to cover the entire abdomen and retroperitoneal space.
A low-dose intravenous diuretic injection of 0.1 mg per kilogram of body weight (total individual dose not exceeding 10 mg) furosemide (Furesis; Orion, Espoo, Finland) was used to enhance excretion 30–60 seconds before the administration of contrast material. A T1-weighted gradient-echo sequence (fat-saturated fast low-angle shot [FLASH]; 117/4.1, 80° flip angle, 7–9 mm section thickness, and 16-second acquisition time) was performed in transverse orientation to cover the whole abdomen and retroperitoneal space 20–30 seconds after administration of 0.1 mmol/kg gadopentetate dimeglumine (Magnevist; Schering, Berlin, Germany).
T1-weighted MR urography was performed with gadolinium-enhanced three-dimensional (3D) FLASH imaging in coronal orientation (4.6/1.8, 30° flip angle, 1.75-mm effective section thickness, 400-mm field of view, 200 x 512 matrix, and 23-second acquisition time). Three-dimensional FLASH imaging was also performed in sagittal orientation on the affected side of the body, when necessary. Three-dimensional FLASH sequences were routinely repeated 5 and 15 minutes after the administration of contrast material, and delayed follow-up was performed when necessary, as determined by the performing radiologist (M.S.). The total MR urographic examination time was calculated by starting at the beginning of the first localizing sequence and ending at acquisition of the last 3D FLASH sequence. Maximum intensity projection images and, occasionally, multiplanar reconstructions and original source images were available as hard copies for evaluation. Observers had access to the workstation (Vision; Siemens, Erlangen, Germany) to review source images.
Excretory urography was performed after a delay of 15–30 minutes and with an intravenous bolus injection of 1.5 mL/kg (total dose not exceeding 100 mL) iohexol (300 mg iodine per milliliter Omnipaque; Nycomed, Cork, Ireland). No abdominal compression was performed. A radiograph of the abdomen was initially obtained, followed by full-sized radiographs obtained 5 and 15 minutes after administration of contrast material. Oblique images of the ureterovesical junction were obtained, if needed, to better visualize the distal ureters. The examination was completed if no obstruction was detected. If an obstruction was noted, follow-up radiographs were obtained at 30 and 60 minutes on the side of the body on which the obstruction occurred, and further radiographs were obtained as needed until the cause and/or level of obstruction were demonstrated, as determined by the performing radiologist. The duration of the excretory urographic examination was calculated by starting from the injection of contrast material and ending at acquisition of the last diagnostic image.
CT and MR imaging examinations were saved on optical disks, and images were retrieved as needed for further evaluation at dedicated workstations. To evaluate the preference for CT or MR urography from the patients’ point of view, patients were interviewed by the radiologist at the end of each study and were asked to state the preferred investigation and the reason for their choice.
Image Interpretation
Excretory urographic images were interpreted by means of consensus by a radiologist (M.S.) and a urologist (A.H.) for the presence, cause, degree and level of obstruction, and extravasation of contrast material. If a patient had more than one ureteral stone, detection of the stone causing the obstruction was noted. A stone was diagnosed if the contrast material–filled ureter terminated at the level of a high-attenuating structure or a calcification seen on precontrast radiographs. The largest diameter of a stone, if present, was measured directly from hard copies and was reported in millimeters after correction of a magnification factor of 1.09 (magnification = [focus-to-film distance/focus-to-object distance]). Exact correction was problematic because of patients’ different body geometries but has been found to result in improved accuracy (24). For simplicity, in the current study, the longest calculated focus-to-object distance was considered constant for all patients. In cases in which a stone was not visualized on excretory urographic images, the size of stones was based on the actual size of retrieved stones, if available, or on US measurements.
MR urographic and CT investigations and reconstructions were all performed by the same radiologist, who was not involved in analyzing images. CT images were evaluated by two experienced radiologists (S.K., A.M.) (observers A and B) independently. T2-weighted and 3D FLASH MR images were first evaluated separately and independently by two other experienced radiologists (K.P., R.L.V.) (observers C and D). The results of these separate readings have been discussed in a previous report (25). The whole MR urographic examination was later evaluated independently by the same two observers (C and D). There was a period of approximately 2 months between the first readings (T2- and T1-weighted sequences) and of at least 6 months for the last reading. Each examination was given a different code not known to the observers to preserve patient anonymity. The observers were aware of the side of the body on which the symptoms occurred. No other clinical data or information from other studies was provided, and the observers were blinded to clinical outcome. CT and MR urographic observers were not involved in analyzing excretory urographic images or in obtaining clinical or radiologic data.
Images were evaluated for the presence and cause of obstruction. At CT, a stone was defined as a calcification within the ureteral lumen. At MR urography, a stone was defined as a complete or partial filling defect within the urinary tract. The largest diameter of the stone, if present, was measured at dedicated workstations and reported in millimeters. Other caliceal stones also were noted. Other causes of obstruction, if present, were defined as extrinsic, intrinsic, or indeterminate. The degree of obstruction was assessed subjectively as not present, low grade, or high grade. The following criteria were used to assess the degree of obstruction at MR urography and excretory urography:
1. No obstruction: no distention of the intrarenal collecting system or ureter, with no delay in excretion.
2. Low-grade obstruction: visualization of the ureter as a persistent column of signal intensity or contrast material proximal to the level or cause of obstruction on the symptomatic side, with mild prominence of the renal pelvis and visualization of the entire urinary tract at 15-minute urography.
3. High-grade obstruction: enlargement of the calices, with blunting of the caliceal fornices, dilatation of the ureter, delayed urography, and increasingly intense nephrogram.
At CT the degree of obstruction was classified as:
1. No obstruction: no distension of the intrarenal collecting system or ureter.
2. Low grade: mild prominence or minimal dilatation of the renal pelvis, with or without mild ureteral prominence.
3. High grade: obvious dilatation of the renal pelvis and intrarenal cavities, with dilatation of the ureter.
In addition, extravasation and perirenal high signal intensity or stranding and level of obstruction were noted. Other secondary signs of obstruction, such as nephromegaly, periureteral and ureterovesical junction edema, and the "tissue rim" sign, were noted. The level of obstruction was classified as the ureteropelvic junction; the proximal, middle, or distal third of the ureter; or the ureterovesical junction. Other possible causes of acute flank pain were also noted. The technical quality of MR imaging and CT examinations was judged as good, suboptimal, or inadequate on the basis of the completeness of visualization of the urinary tract and the presence of artifacts influencing image interpretation and evaluation.
Statistical Analysis
The sensitivity, specificity, and overall accuracy of MR urography and CT were calculated for all observers separately. The 
statistic was used to measure interobserver and intertechnique agreement. Strength of agreement was classified as slight (
0.20), fair (0.21–0.40), moderate (0.41–0.60), substantial (0.61–0.80), or excellent (0.81–1.00) (26).
The size of obstructing ureteral stones measured at CT and MR urography was correlated to the final size of the stones by using the Spearman correlation coefficient and was considered significant if P was less than .05. Furthermore, the Spearman correlation coefficient was used to determine whether there was statistical correlation between the findings of stone and obstruction between the paired kidneys of the same patient and with random choice of pairs. Analyses were performed separately for observers A, B, C, and D.
Statistical analysis was performed by using a personal computer statistical software package (SPSS version 9.0 for Windows; SPSS, Chicago, Ill).
|
RESULTS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
|---|
At final diagnosis, 32 (65%) patients were found to have ureteral stones causing unilateral obstruction. Three of these patients had two ureteral stones each. Other final diagnoses were acute appendicitis (one patient), acute ulcerative colitis (one patient), urinary tract infection (one patient), sactosalpinx and tubal torsion (one patient), and biliary colic (one patient). In all other cases (n = 12), the cause of flank pain remained undetermined, and symptoms had resolved at clinical follow-up.
In 21 patients, the stone passed spontaneously (stones were retrieved in 13 patients; in the other eight, the stone could no longer be visualized when controlled by plain abdominal radiographs or excretory urography). In five patients, ureteral stones were treated with extracorporeal shock-wave lithotripsy. Five patients underwent ureteroscopy and stone extraction. The last patient was asymptomatic at follow-up and refused further investigation. The passage of a stone was not confirmed in this patient, but the clinical and radiologic diagnoses were of a definite small ureteral stone. Because a statistically significant negative correlation was detected between the paired kidneys, which proved to be clearly higher than when the kidneys were randomly paired, in this study, statistical analyses were performed on a per-patient-unit (on the basis of the side of the body on which symptoms of acute flank pain occurred) basis rather than on a per-kidney-unit (two kidneys per patient) basis.
At CT, observers A and B correctly detected the cause of obstruction in 29 patients (Fig 1). Observers had three false-negative findings each, and observer B had one false-positive finding (Fig 2). At MR urography, observer C correctly detected 30 ureteral stones, with two false-negative findings. Observer D correctly interpreted all cases. At CT, a unilateral ureteral obstruction was detected in 30 patients and missed in two patients by observer A. Observer B detected obstruction in 32 patients (including one false-positive finding) and missed an obstruction in one patient. At MR urography, both observers correctly interpreted all cases. The sensitivity, specificity, overall accuracy, and interobserver agreement values for the detection of ureteral stones and obstruction, as compared with the final diagnosis, are shown in Table 1. Other caliceal stones were found at CT in 24 kidneys by both observers and at MR urography in two and eight kidneys by observers C and D, respectively.
|
|
|
statistic) for the degree of obstruction was 0.51 for observers at CT and 0.88 at MR urography. For the level of obstruction, interobserver agreement was 0.81 and 0.83 for CT and MR urography, respectively.
|
|
|
|
|
|
|
|
|
Stranding or perirenal high signal intensity was interpreted as present in 27, 26, 28, and 30 kidneys for observers A, B, C, and D, respectively, including two false-positive interpretations each by observers A and B. The diagnostic accuracy of perirenal high signal intensity or stranding in predicting acute ureteral obstruction on the side of the body on which symptoms occurred is shown in Table 4.
|
Finally, 40 patients stated that CT was their preferred examination because of its short duration. Only five patients mentioned MR urography as the preferred examination, because of "the relaxed atmosphere" in the magnetic tube and "efficient air conditioning." Four patients believed that the imaging modalities were equivalent.
|
DISCUSSION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
|---|
A ureteral stone is traditionally diagnosed when a calcific opacity is detected in the ureteral lumen. This presents a challenge at MR urography, at which calcifications are not directly visualized, and detection of a ureteral stone is based on a filling defect inside the ureteral lumen, a sign that is nonspecific and may also represent a blood clot or tumor (28,29). When obstruction is due to another cause, such as an intraluminal neoplasm, it can usually be identified with conventional MR sequences (28). Although acute obstruction is most frequently secondary to ureteric calculus, a signal-void intraluminal filling defect with smooth margins seen with both T1- and T2-weighted sequences and a lack of enhancement after contrast material administration are usually sufficient for diagnosing a ureteral stone. Nevertheless, this is not always straightforward, and severe surrounding soft-tissue edema can mimic or obscure a tumorous process. In this study, although a filling defect was visualized in two cases, observer C could not rule out the possibility of a tumor as the underlying abnormality, because of severe ureterovesical junction edema. In such unclear cases, it is advisable to obtain a radiograph of the abdomen to confirm a calcification at the site of obstruction. Unfortunately, our consecutive patient population did not include individuals with urologic abnormalities other than ureteral stones.
T2-weighted sequences are not always sufficient in detecting small ureteral stones, and T1- and T2-weighted sequences complement each other. Although there are no prospective MR studies, to our knowledge, of the evaluation of patients with acute flank pain, a recent study by Verswijvel et al (23) showed the high diagnostic accuracy of contrast-enhanced T1-weighted imaging in demonstrating the underlying urologic abnormality, including tumors and ureteral stones.
Occasional difficulty in differentiating a ureteral stone from a phlebolith is a known limitation of CT that is discussed in several previous articles (7,9,30). However, with experience and use of secondary signs of obstruction, this difficulty can usually be overcome (31). The "comet sign", lower attenuation, and absence of a soft-tissue rim sign might help in differentiating a pelvic phlebolith from a ureteral stone (30). In our study, observer B had one false-positive result. Phleboliths are not visualized at MR urography, and thus there were no misinterpreted cases.
A major advantage of helical CT over excretory urography is that the exact stone burden is revealed because of markedly improved soft-tissue contrast (8). In our study, CT clearly depicted even tiny caliceal stones, whereas at MR urography, both observers failed to visualize nearly all small caliceal stones. Increasing the spatial resolution might be a solution to this problem, by reducing both the field of view and the effective section thickness to cover only the kidneys (decreased matrix size); however, further improvement in the spatial resolution of MR imagers is obviously still needed.
Both CT and MR urography were highly accurate in demonstrating obstruction. Although administration of a diuretic before the performance of 3D FLASH sequences might, presumably, increase the frequency of detected obstruction through rapidly increased diuresis, heavily T2-weighted sequences alone without any diuretic are also highly accurate in demonstrating minimal obstruction, as has been reported by other investigators (15,32,33). Central fluid collection was detected with CT and T2-weighted MR sequences in patients with extravasation; hence, there is no conclusive data to assume possible fornicial rupture due to the use of such a small amount of diuretic. Both CT and MR urography were equally effective in demonstrating the level of obstruction.
Another limitation of CT is the inability to directly evaluate the excretory function of kidneys. Nevertheless, for evaluation of degree of obstruction, agreement of CT findings with excretory urographic findings was moderate for both observers, based only on estimation of the degree of urinary tract dilation. Excretory MR urography enables evaluation of the excretory function of the kidney in the same way as excretory urography, thus explaining the higher agreement. However, degree of obstruction is not a crucial piece of information that can influence patient treatment. Stone size and location, patient symptoms, and absence of infection are the most important parameters used to determine need for urologic intervention (7). CT already can be used to provide the needed radiologic information and to measure the size of ureteral stones more accurately than can excretory urography or nephrotomography (24). In our study, the correlation of stone size was clearly better when measured from CT images rather than from MR urographic images, which we consider an important strength of CT over MR urography. In our study and clinical practice, we have noted slight underestimation of stone size, possibly because of partial volume effect obscuring the stone margins from the surrounding high urine signal.
Perirenal edema seen as soft-tissue stranding at CT and as high signal intensity at MR urography is another useful and highly accurate sign in predicting acute ureteric obstruction. Stranding is less prominent at CT than at MR urography (34), as was also noted in our study. Minimal perirenal edema or fluid collection was easily detected with heavily T2-weighted sequences. However, this is a nonspecific sign, and any insult to the kidney may result in perirenal stranding.
Another advantage of helical CT is short imaging time. The examination time necessary to reveal the cause of obstruction might be markedly prolonged at excretory urography and excretory MR urography. Occasionally, in cases of severe obstruction, T2-weighted MR sequences may prove sufficient in determining the cause of obstruction and thus eliminating the need for prolonged follow-up sequences. Nevertheless, imaging time will still be longer than for CT.
CT and MR urography were equally accurate in excluding other causes of acute flank pain. MR urography did well in detecting inflammatory changes in the three patients with extraurinary diseases causing acute flank pain symptoms and showed a gall bladder stone in a fourth patient.
MR urographic investigation demands the presence of highly qualified radiologists with thorough knowledge of and experience in MR imaging, as well as other qualified personnel. Because most of our patients with acute flank pain present to the emergency department at times other than during duty hours, MR urography is likely to be performed the next day, thus resulting in delayed diagnosis and management. It might also be speculated that the good performance of MR urography was due in part to the retrospective image analysis performed by the observers in the current study, which is different from that performed by the physician on call, who has to make a rapid conclusive decision on whether or not a patient has ureteral stones or other underlying disease. In addition to the higher cost of MR urography and limited availability, two other important factors should be considered in choosing the imaging technique to evaluate acute flank pain: clinician acceptance of the new imaging modalities, and patient satisfaction. The urologic surgeons at our hospital have readily accepted both CT and MR urography, and our limited interview showed that a majority of patients prefer CT over MR urography. Furthermore, helical CT is widely available and easy to perform, and all radiologists and technicians are well acquainted with this imaging modality.
In this study, we have shown the high diagnostic accuracy of MR urography in examining patients with acute flank pain. It should, however, be reserved for selected patients, in our opinion, when the use of contrast medium or ionized radiation is undesirable (eg, in pregnant women, cooperative children, and young adults), in spite of the fact that pregnant women and children were excluded from this study, since it would be more difficult to perform a controlled study of these populations. At our hospital, we now also recommend MR urography in patients with nephropathy when information about anatomic details of the pelvicaliceal systems, ureters, and excretory function of the kidney is needed. Another possible application of MR urography is in patients with human immunodeficiency virus who are undergoing crixivan (Indivar; Merck, Rahway, NJ) therapy, since they can present with nonopaque stones (35), and in patients with atypical symptoms, especially if there is suspicion of an extraurinary inflammatory process or biliary disease.
In conclusion, in routine clinical practice, unenhanced helical CT is meritoriously the investigation of choice in the examination of patients with acute flank pain. MR urography is an acceptable substitute when other clinical advantages favoring MR urography are present.
|
ACKNOWLEDGMENTS |
|---|
|
FOOTNOTES |
|---|
Author contributions: Guarantor of integrity of entire study, M.S.; study concepts, M.S., R.L.V., K.P., M.A.O.; study design, K.P., M.S., R.L.V.; literature research, M.S.; clinical studies, M.S.; data acquisition, M.S.; data analysis/interpretation, R.L.V., K.P., S.K., A.M., A.H., M.S.; statistical analysis, M.S.; manuscript preparation, M.S.; manuscript definition of intellectual content, M.S., R.L.V.; manuscript editing, revision/review, and final version approval, all authors.
|
REFERENCES |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
|---|
This article has been cited by other articles:
|
|
 |
|
  T. Niemann, T. Kollmann, and G. Bongartz Diagnostic Performance of Low-Dose CT for the Detection of Urolithiasis: A Meta-Analysis Am. J. Roentgenol., August 1, 2008; 191(2): 396 - 401. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S J Freeman and H Sells Investigation of loin pain Imaging, March 1, 2008; 20(1): 38 - 56. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 E. Lazarus, W. W. Mayo-Smith, M. B. Mainiero, and P. K. Spencer CT in the Evaluation of Nontraumatic Abdominal Pain in Pregnant Women Radiology, September 1, 2007; 244(3): 784 - 790. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 I. Pedrosa, E. A. Zeikus, D. Levine, and N. M. Rofsky MR Imaging of Acute Right Lower Quadrant Pain in Pregnant and Nonpregnant Patients RadioGraphics, May 1, 2007; 27(3): 721 - 743. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. I. Katz, S. Saluja, J. A. Brink, and H. P. Forman Radiation Dose Associated with Unenhanced CT for Suspected Renal Colic: Impact of Repetitive Studies. Am. J. Roentgenol., April 1, 2006; 186(4): 1120 - 1124. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S J Freeman and H Sells Investigation of loin pain Imaging, August 1, 2005; 17(1): 19 - 33. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S K Morcos Ureteric obstruction and intravascular administration of contrast media: is there a risk? Br. J. Radiol., August 1, 2003; 76(908): 564 - 565. [Full Text] [PDF]
|
|
|
|
|
|
E. P. Tamm, P. M. Silverman, and W. P. Shuman Evaluation of the Patient with Flank Pain and Possible Ureteral Calculus Radiology, August 1, 2003; 228(2): 319 - 329. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| RADIOLOGY | RADIOGRAPHICS | RSNA JOURNALS ONLINE |
