Patrice Taourel

Iliopsoas impingement on the acetabular component: radiologic and computed tomography findings of a rare hip prosthesis complication in eight cases.

Objective To describe the radiographic and computed tomography (CT) scan features of iliopsoas impingement on the acetabular component (IPI) in total hip arthroplasty. Method Eight cases of iliopsoas impingement were diagnosed and confirmed by surgical revision. The plain film radiograph findings and CT scan findings were compared with those of two control populations (8 patients with painless total hip prosthesis and 16 patients with other complications confirmed by surgical revision). Results An oversized cup was found in four hips with IPI (50%) and in one hip with another complication (6%). Coronal inclination of the acetabular cup was normal in the IPI group and in the two control groups, with a similar mean cup size. All patients with IPI had an acetabular cup overhang of more than 12 mm. Conversely, in the two control groups, the overhang, present in three and two cases, respectively, was always less than 8 mm. Iliopsoas bursal effusion was present in four hips with IPI and three hips with other complications and was never present in normal prostheses. Conclusion More than a 12-mm overhang of the acetabular cup is a sensitive and specific parameter for diagnosing IPI.

Characterization of Small Solid Renal Lesions: Can Benign and Malignant Tumors Be Differentiated With CT?

OBJECTIVE The purpose of this study was to evaluate the diagnostic performance of CT in determining whether a small solid renal enhancing mass is benign or malignant. MATERIALS AND METHODS Ninety-nine biopsies of enhancing solid renal masses 4 cm or smaller without fat on CT scans were performed under CT fluoroscopic guidance. The growth pattern, interface with parenchyma, presence of a scar and segmental inversion enhancement, unenhanced CT histogram, and pattern and degree of enhancement on triphasic MDCT images were independently evaluated by two radiologists. Biopsy and pathology reports were used as the reference standard, and imaging follow-up of benign lesions was performed for at least 1 year. Statistical analysis was performed to determine the significance of CT criteria in differentiating malignant from benign lesions. RESULTS Of the 99 lesions, 74 (75%) were malignant at biopsy, and 25 (25%) were benign. Lesions with gradual enhancement were more likely to be benign. No significant correlation was found between other CT features and a malignant or benign diagnosis. The sensitivity, specificity, and positive and negative predictive values of progressive enhancement for a diagnosis of benignity were 60%, 73%, 43%, and 84%. CONCLUSION In the evaluation of enhancing small solid renal lesions without fat, no CT criteria were of substantial help in differentiating malignant from benign lesions.

Multidetector CT of bowel obstruction: value of post-processing

The value of imaging in patients with suspicion of bowel obstruction is dependent on the ability to answer questions relevant to the clinical management of patients. Is there mechanical obstruction? Is it a small bowel obstruction (SBO) or a large bowel obstruction (LBO)? What is the transition point? What is the cause of the obstruction? What is the severity of the obstruction? The results of studies published more than 10 years ago using axial and single-slice helical CT gave rise to findings based on axial slices that enables CT to answer these different questions. With the recent advent of multislice CT, large numbers of thin sections can be generated with short image intervals, which is well suited to postprocessing. Postprocessing techniques include standard reformatting methods such as sagittal, coronal and oblique reformatting, curved reformatting, maximum and minimum-intensity projection, variable thickness viewing, and volume and surface rendering. This pictorial review illustrates the added value of postprocessing for answering different questions concerning patients with suspicion of bowel obstruction.

Interstitial pregnancy: role of MRI

We report the MRI features of two cases of interstitial pregnancy. In both cases, MRI was able to localize the ectopic pregnancy by showing a gestational structure surrounded by a thick wall in the upper part of the uterine wall separated from the endometrium by an uninterrupted junctional zone. Because US may confuse angular and interstitial pregnancies and because interstitial pregnancy has a particular evolutive course, MR imaging may play a key role in the diagnosis and management of women with interstitial pregnancy.

Increased Unenhanced Bowel-Wall Attenuation at Multidetector CT Is Highly Specific of Ischemia Complicating Small-Bowel Obstruction

PURPOSE To evaluate performance of increased bowel-wall attenuation on unenhanced 64-section multidetector computed tomographic (CT) images for diagnosing bowel-wall ischemia in patients with mechanical small-bowel obstruction (SBO) and to evaluate the diagnostic accuracy of multidetector CT in detecting small-bowel ischemia complicating SBO, with surgical and histopathologic findings as reference standard. MATERIALS AND METHODS The local institutional review board approved this retrospective study; informed consent requirement was waived. In 44 patients (10 men, 34 women; age range, 30-100 years) who were admitted because they were suspected of having SBO and treated surgically within the next 7 days, 45 multidetector CT scans were retrospectively reviewed. Two gastrointestinal radiologists performed independent blinded reviews of images to identify specific signs of ischemia; disagreements were resolved in consensus with a third gastrointestinal radiologist. Results were compared with both findings in prospective radiology reports and surgical and histopathologic findings. Fisher exact and χ(2) tests were used to assess associations between CT signs and ischemia, and the κ statistic was used to assess interobserver agreement. RESULTS In 19 of 45 (42%) multidetector CT scans, ischemia was confirmed at surgery and/or histopathologic examination. Increased bowel-wall attenuation on unenhanced images was significantly associated with ischemia (P < .0001); in this highly selected population, this sign had a 100% (24 of 24) specificity and a 56% (10 of 18) sensitivity. Sensitivity and specificity of multidetector CT for ischemia were 63% (12 of 19) and 92% (24 of 26), respectively, for the prospective reports and 84% (16 of 19) and 96% (25 of 26), respectively, for the consensus review. Decreased segmental bowel-wall enhancement was the most accurate 64-section multidetector CT sign for diagnosing ischemia (sensitivity, 78% [14 of 18]; specificity, 96% [24 of 25]; P < .0001). The small-bowel feces sign was significantly associated with ischemia (P = .0308). CONCLUSION Increased bowel-wall attenuation on unenhanced 64-section multidetector CT images is a specific sign for ischemia complicating SBO. Diagnostic accuracy of 64-section multidetector CT for ischemia associated with SBO was excellent.

Value of computed tomography in the diagnosis of the cause of nontraumatic gastrointestinal tract perforation.

Objective: To identify computed tomographic features with a high predictive value to differentiate gastroduodenal ulcer perforations from other causes of perforations in patients with a non-traumatic-free pneumoperitoneum. Materials and Methods: Computed tomographic scans of 81 patients with a non-traumatic-free pneumoperitoneum were reviewed for direct visualization of the perforation site and indirect findings of the perforation, including the presence, amount, and localization of air and ascites in the peritoneal cavity, mural thickness of the gastrointestinal tract, perigastrointestinal fat stranding, intestinal ischemia, fecal peritonitis, abscess, and portomesenteric venous gas. Results: The perforation site was directly visualized in 16 (41%) of 39 patients with gastroduodenal ulcer perforation and in 5 (12%) of 42 patients with other causes of perforation. The findings with a positive predictive value of more than 90% for gastroduodenal ulcer perforation were the presence of local fluid between the duodenum and the pancreatic head and the combination of local gastroduodenal wall thickening and fat stranding. The presence of abscess in the peritoneal cavity or fecal peritonitis, portomesenteric gas, or bowel ischemia findings had a positive predictive value of 100% for the diagnosis of other perforations. Conclusions: Indirect computed tomographic findings are helpful for differentiating gastroduodenal ulcer perforation from other causes of perforations.

Direct visualization of perforation sites in patients with a non-traumatic free pneumoperitoneum: added diagnostic value of thin transverse slices and coronal and sagittal reformations for multi-detector CT

The incremental diagnostic value of adding 1.25-mm slices and coronal and sagittal reformatting to 5-mm axial reconstructions for direct visualization of the perforation site in patients with non-traumatic free pneumoperitoneum was assessed. Forty patients with non-traumatic bowel perforation and free pneumoperitoneum underwent computed tomography (CT). The perforation was gastroduodenal in 18 patients and involved the small or large bowel in 22 patients. Transverse scans were reconstructed with 5-mm thick sections at 5-mm intervals and 1.25-mm-thick sections at 1.25-mm intervals. The second data set was reformatted coronally and sagittaly with 3-mm-thick sections at 3-mm intervals. Three independent blinded readers interpreted 5-mm transverse scans, then combined 1.25-mm and 5-mm-transverse scans, and then combined transverse, coronal and sagittal scans. The rate of identification of the perforation site ranged from 43% to 53% with the combined axial, sagittal and coronal scans, from 28% to 48% with the 1.25- and 5-mm transverse scans, and from 5% to 20% only with the 5-mm thick transverse scans. The agreement between readers was significantly higher with thin slices and reformatting. The use of 1.25-mm axial slices and reformations intrinsically contained more useful diagnostic information than 5-mm axial slices alone for diagnosis of the perforation site in patients with pneumoperitoneum.

What are the specific computed tomography scan criteria that can predict or exclude the need for renal angioembolization after high-grade renal trauma in a conservative management strategy?

BACKGROUND The indications of renal angioembolization for patients with high-grade renal trauma (HGRT) are based on angiographic criteria to reduce the failure rate of conservative management (CM). There is no consensus to predict or exclude an indication of renal angioembolization with a computed tomography (CT) scan. The aim of this study was to evaluate CT-specific criteria to predict or exclude the need for renal embolization. METHODS All traumatized patients admitted with renal injury were considered between 2005 and 2009. We included all patients who had an HGRT (classified by American Association for the Surgery of Trauma Organ Injury Scale grade≥3) treated by CM. We collected the demographic, CT, angiographic, management, and outcome data for these patients. CT criteria were retrospectively studied to define their predictive values for renal embolization. RESULTS Among 101 patients with renal injury, 58 were HGRT, and 53 of them were treated by CM. Ten patients (19%) received renal embolization because of an ongoing renal hemorrhage. There was no significant difference for urologic interventions (2 [20%] vs. 7 [16%]), CM failure rate (1 [10%] vs. 2 [5%]), and during hospital stay between these patients and those who did not received embolization. None of the CT criteria had a negative predictive value for renal embolization to 100%, only the absence of intravascular contrast extravasation associated with a perirenal hematoma rim distance<25 mm excludes an indication for embolization. CONCLUSIONS In patients with HGRT who had bleeding, a strategy of targeted angiography can be realized safely in using specific CT scan criteria that can predict with high accuracy and exclude the need for embolization, without reducing the success rate of CM.

Adhesive Small-Bowel Obstruction: Value of CT in Identifying Findings Associated with the Effectiveness of Nonsurgical Treatment

PURPOSE To identify computed tomographic (CT) findings that are associated with the effectiveness of nonsurgical treatment in patients with adhesive small-bowel obstruction ( SBO small-bowel obstruction ) that was initially treated medically. MATERIALS AND METHODS The local institutional review board approved this retrospective study; the informed consent requirement was waived. Multi-detector row CT studies in 159 patients (64 women, 95 men; median age, 69 years) with adhesive SBO small-bowel obstruction that was initially treated medically were reviewed retrospectively and independently by two emergency radiologists to identify numerous CT findings that could be associated with the effectiveness of nonsurgical treatment. Results were compared according to the success or failure of nonsurgical treatment. Univariate statistical analyses were performed for qualitative and quantitative data, as appropriate, and each significant parameter was entered in a multivariate logistic regression analysis. The κ statistic and correlation coefficients were used to assess interobserver agreement, as appropriate. RESULTS Nonsurgical treatment succeeded in 113 patients (71%) and failed in 46 patients (29%). At univariate analysis, an anterior parietal adhesion, a feces sign, and the lack of a beak sign were associated with successful nonsurgical treatment, whereas two beak signs or more, a whirl sign, a C- or U-shaped appearance of the bowel loop, and a high degree of obstruction were associated with nonsurgical treatment failure. At multivariate analysis, fewer than two beak signs and the presence of an anterior parietal adhesion were independent predictors of the effectiveness of nonsurgical treatment, with odds ratios of 0.27 and 0.11, respectively. CONCLUSION The number of beak signs and the location of the transition zone in relation to the anterior peritoneal layer are independent signs associated with the success or failure of nonsurgical treatment.

Undiagnosed Breast Cancer at MR Imaging: Analysis of Causes

PURPOSE To retrospectively review the causes of false-negative results on prior magnetic resonance (MR) imaging studies in patients who developed breast cancer as revealed on a follow-up MR imaging study and to determine the presumptive causes of these false-negative findings. MATERIALS AND METHODS Fifty-eight pairs of MR imaging studies from one institution were assessed, consisting of a prior study without a diagnosis of cancer and a diagnostic study with subsequent findings of 60 cancers in 58 women at MR imaging (mean interval between prior and diagnostic MR examinations, 13.8 months). Two radiologists reviewed in consensus, in a nonblinded fashion, each pair of MR studies, comparing the diagnostic and the prior MR imaging studies to evaluate the rate of false-negative findings. The prospective reports were then analyzed to classify false-negatives findings in breast enhancement of breast cancers not identified at the time of imaging, potentially misinterpreted, and mismanaged. False-negative results on prior MR studies were retrospectively reassessed to identify possibly reasons why cancers had been not recognized, potentially misinterpreted, or mismanaged. RESULTS Twenty-eight (47% [95% confidence interval {CI}: 34%, 59%]) of the 60 cancers were retrospectively diagnosed as Breast Imaging Reporting and Data System grade 3, 4, or 5 lesions. Analysis of the prospective reports showed that six lesions (10% [95% CI: 2%, 18%]) had been not identified at the time of diagnosis, 15 lesions (25% [95% CI: 14%, 36%]) were potentially misinterpreted, and seven lesions (12% [95% CI: 3%, 20%]) were mismanaged. The main causes of misinterpretation were smooth margins of a mass (n=4), stability in size (n=3), and location of a nonmass in a postsurgical area (n=5). Mismanagement was mainly due to inadequate correlations between MR imaging and ultrasonographic (US) features, with inaccurate sampling with US guidance in five cases. CONCLUSION In patients with breast cancer seen at MR imaging, retrospective evaluation of the prior MR imaging studies showed potential observer error in 47% of cases, resulting more from misinterpretation than from nonrecognition or mismanagement of cancers.