Retroperitoneal Fasciitis: Spectrum of CT Findings in the Abdomen and Pelvis.

Retroperitoneal fasciitis is a rare but potentially lethal complication of infection. Early diagnosis is crucial and is usually made when there is a high degree of clinical suspicion combined with characteristic imaging findings leading to early surgical intervention. Computed tomography (CT) can play a central role in demonstrating early findings, assessing the extent of disease to help determine the best surgical approach, identifying the primary source of infection, and evaluating the treatment response. The possible presence of retroperitoneal fasciitis should be considered in patients presenting with symptoms of sepsis, including pain that is disproportionate with the clinical abnormality. When retroperitoneal fasciitis is suspected, emergency CT can facilitate early diagnosis and evaluation of the extent of disease. Common findings at CT include fascial thickening and enhancement, muscular edema, fat stranding, fluid collections, and abscess formation. Gas tracking along fascial planes in the retroperitoneum is the hallmark of retroperitoneal fasciitis but is not seen in all cases. Another important clue to the diagnosis is asymmetric involvement of the retroperitoneal fascial planes and deep tissues. Fasciitis in the retroperitoneum may originate from infected retroperitoneal organs or from infection that spreads along indirect and/or direct pathways from a primary source elsewhere in the body. Findings of indirect tracking and transgression of fascial planes may indicate more severe infection associated with the necrotizing form of retroperitoneal fasciitis. Despite aggressive antibiotic treatment, early and repeated surgical débridement may be required to remove nonviable tissue in patients with the necrotizing form of retroperitoneal fasciitis. Awareness of the anatomy of the retroperitoneum, potential routes of spread of infection, and the spectrum of CT findings in retroperitoneal fasciitis is needed to achieve prompt diagnosis and guide treatment.

How useful is preoperative imaging for tumor, node, metastasis (TNM) staging of gastric cancer? A meta-analysis.

BACKGROUND: Surgery is the fundamental curative option for gastric cancer patients. Imaging scans are routinely prescribed in an attempt to stage the disease prior to surgery. Consequently, the correlation between radiology exams and pathology is crucial for appropriate treatment planning. METHODS: Systematic searches were conducted using Medline, Embase, and the Cochrane Central Register of Controlled Trials from January 1, 1998 to December 1, 2009. We calculated the accuracy, overstaging rate, understaging rate, Kappa statistic, sensitivity, and specificity for abdominal ultrasound (AUS), computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET) with respect to the gold standard (pathology). We also compared the performance of CT by detector number and image type. A meta-analysis was performed. RESULTS: For pre-operative T staging MRI scans had better performance accuracy than CT and AUS; CT scanners using ≥ 4 detectors and multi-planar reformatted (MPR) images had higher staging performances than scanners with <4 detectors and axial images only. For pre-operative N staging PET had the lowest sensitivity, but the highest specificity among modalities; CT performance did not significantly differ by detector number or addition of MPR images. For pre-operative M staging performance did not significantly differ by modality, detector number, or MPR images. CONCLUSIONS: The agreement between pre-operative TNM staging by imaging scans and post-operative staging by pathology is not perfect and may affect treatment decisions. Operator dependence and heterogeneity of data may account for the variations in staging performance. Physicians should consider this discrepancy when creating their treatment plans.

Follow-up Recommendations for Completely Resected Gastroenteropancreatic Neuroendocrine Tumors.

There is no consensus on optimal follow-up for completely resected gastroenteropancreatic neuroendocrine tumors. Published guidelines for follow-up are complex and emphasize closer surveillance in the first 3 years after resection. Neuroendocrine tumors have a different pattern and timescale of recurrence, and thus require more practical and tailored follow-up. The Commonwealth Neuroendocrine Tumour Collaboration convened an international multidisciplinary expert panel, in collaboration with the North American Neuroendocrine Tumor Society, to create patient-centered follow-up recommendations for completely resected gastroenteropancreatic neuroendocrine tumors. This panel used the RAND/UCLA (University of California, Los Angeles) Appropriateness Method to generate recommendations. A large international survey was conducted outlining current the surveillance practice of neuroendocrine tumor practitioners and shortcomings of the current guidelines. A systematic review of available data to date was supplemented by recurrence data from 2 large patient series. The resultant guidelines suggest follow-up for at least 10 years for fully resected small-bowel and pancreatic neuroendocrine tumors and also identify clinical situations in which no follow-up is required. These recommendations stratify follow-up strategies based on evidence-based prognostic factors that allow for a more individualized patient-centered approach to this complex and heterogeneous malignant neoplasm.

MR pulse sequences: what every radiologist wants to know but is afraid to ask.

The use of magnetic resonance (MR) imaging is growing exponentially, in part because of the excellent anatomic and pathologic detail provided by the modality and because of recent technologic advances that have led to faster acquisition times. Radiology residents now are introduced in their 1st year of training to the MR pulse sequences routinely used in clinical imaging, including various spin-echo, gradient-echo, inversion-recovery, echo-planar imaging, and MR angiographic sequences. However, to make optimal use of these techniques, radiologists also need a basic knowledge of the physics of MR imaging, including T1 recovery, T2 and T2* decay, repetition time, echo time, and chemical shift effects. In addition, an understanding of contrast weighting is very helpful to obtain better depiction of specific tissues for the diagnosis of various pathologic processes.

Multidetector helical CT in the evaluation of acute small bowel obstruction: comparison of non-enhanced (no oral, rectal or IV contrast) and IV enhanced CT.

PURPOSE: To compare accuracy of non-enhanced CT (NECT) (no oral or IV contrast) and enhanced CT (ECT) (IV enhanced only) to diagnose small bowel obstruction and evaluate reviewer's experience impact. MATERIALS AND METHODS: Ninety-nine adult patients underwent 105 NECT and ECT (6 patients had 2 examinations) on a four-detector CT. An abdominal radiologist, an abdominal imaging fellow, a second-year radiology resident retrospectively reviewed NECTs and ECTs separately and independently blinded to outcome. Discrepancy of diameter of proximal and distal small bowel+/-a transition was considered indication of mechanical bowel obstruction. Reference standard was surgery in 26 and chart review in 79. RESULTS: Mechanical obstruction was present in 56% (59/105). The average sensitivity, specificity, negative and positive predictive and accuracy values for NECT were 88.1% (CI: 80-96%), 77% (CI: 65-89%), 83.0% (CI: 72-95%), 83% (CI: 74-92%), and 83% (CI: 76-90%) with no significant difference between three reviewers. The corresponding numbers for ECT were 87.6% (CI: 79-96%), 75% (CI: 63-88%), 82.6.0% (CI: 71-94%), 82.1% (CI: 73-92%), and 82% (CI: 75-90%) (p>0.5). Area under curve (AUC) of ROC curves of three reviewers did not show significant statistical difference (p>0.5). CONCLUSIONS: NECT and ECT have comparable accuracy to diagnose mechanical small bowel obstruction and can be interpreted by reviewers with different levels of expertise.