Multidetector CT of vascular compression syndromes in the abdomen and pelvis.

Certain abdominopelvic vascular structures may be compressed by adjacent anatomic structures or may cause compression of adjacent hollow viscera. Such compressions may be asymptomatic; when symptomatic, however, they can lead to a variety of uncommon syndromes in the abdomen and pelvis, including median arcuate ligament syndrome, May-Thurner syndrome, nutcracker syndrome, superior mesenteric artery syndrome, ureteropelvic junction obstruction, ovarian vein syndrome, and other forms of ureteral compression. These syndromes, the pathogenesis of some of which remains controversial, can result in nonspecific symptoms of epigastric or flank pain, weight loss, nausea and vomiting, hematuria, or urinary tract infection. Direct venography or duplex ultrasonography can provide hemodynamic information in cases of vascular compression. However, multidetector computed tomography is particularly useful in that it allows a comprehensive single-study evaluation of the anatomy and resultant morphologic changes. Anatomic findings that can predispose to these syndromes may be encountered in patients who are undergoing imaging for unrelated reasons. However, the diagnosis of these syndromes should not be made on the basis of imaging findings alone. Severely symptomatic patients require treatment, which is generally surgical, although endovascular techniques are increasingly being used to treat venous compressions.

The utility of secretin-enhanced MRCP in diagnosing congenital anomalies.

PURPOSE: To assess the additional value of secretin-enhanced MRCP (SMRCP) over conventional MRCP in diagnosing divisum. METHODS: Retrospective HIPAA-compliant and IRB-approved review found 140 patients with SMRCP and ERCP correlation within 6 months of each other. All studies were anonymized and the SMRCP images (SMRCP image set) were separated from 2D and 3D MRCP and axial and coronal T2-weighted images (conventional MRI image set). Each image set on each patient was assigned different and randomized case numbers. Two reviewers (R1 and R2) independently reviewed the image sets for divisum vs. no divisum, complete divisum vs. incomplete divisum, and the certainty of diagnosis (1 = definitely certain, 2 = moderately certain, and 3 = unsure). ERCP findings were taken as gold standard. RESULTS: There was no difference in age and gender between the divisum (n = 97, with 13 incomplete divisum) and no divisum (n = 43) groups. In diagnosing divisum anatomy, the sensitivity was higher for SMRCP compared to conventional MRI for R1 (84.5 vs. 72.2, p = 0.02) but not R2 (89.7 vs. 84.4, p = 0.25). The specificity was higher in SMRCP image set compared to conventional MRI (R1: 88.1 vs. 76.2, p = 0.01; R2: 81.4 vs. 65.1, p < 0.001). The mean area under ROC curve was higher for SMRCP image set (R1: 0.86 vs. 0.74, p = 0.01; R2: 0.87 vs. 0.74, p = 0.01). The certainty of diagnosis was higher in SMRCP image set compared to conventional MRI (p = 0.02 for both reviewers). SMRCP was not found to be superior in distinguishing incomplete from complete divisum. The main reasons for erroneous SMRCP diagnosis were the presence of an ansa loop in the main duct and ductal strictures due to chronic pancreatitis. CONCLUSION: Even though the reviewers had more sequences (axial and coronal) to evaluate in the non-secretin image set, there was some improvement in diagnosing divisum with SMRCP.

Abdominal manifestations of neurologic disorders.

A variety of disorders-including infectious, inflammatory, hereditary, and metabolic diseases-may affect both the brain and abdominal cavity, and the findings in one region may help establish the diagnosis or limit the differential diagnosis. Establishing an accurate early diagnosis enables clinicians to adequately manage these unusual diseases and potentially avert life-threatening complications. For example, an early diagnosis of Gardner syndrome enables annual sigmoid- or colonoscopy and ultrasonography. In many conditions, abdominal manifestations precede neurologic manifestations and may have prognostic significance. Patients with celiac disease more often present with abdominal manifestations such as duodenitis, slow transit time, reversal of the jejunal-ileal fold pattern, and transient small bowel intussusception than with intracranial manifestations. In other conditions, the neurologic manifestations may be the same as the presenting symptoms. For example, patients with Gardner syndrome may initially present with multiple mandibular or sinonasal osteomas. In addition, sarcoidosis may manifest with multifocal enhancing dural masses. Abdominal and neurologic manifestations may even occur simultaneously, as in several of the phakomatoses such as neurofibromatosis type 1, tuberous sclerosis complex, and von Hippel-Lindau syndrome. Ultimately, familiarity with the appearances of these conditions allows radiologists to pinpoint a diagnosis, even when imaging findings in either location are nonspecific.

Urinary bladder cancer: role of MR imaging.

Urinary bladder cancer is a heterogeneous disease with a variety of pathologic features, cytogenetic characteristics, and natural histories. It is the fourth most common cancer in males and the tenth most common cancer in females. Urinary bladder cancer has a high recurrence rate, necessitating long-term surveillance after initial therapy. Early detection is important, since up to 47% of bladder cancer-related deaths may have been avoided. Conventional computed tomography (CT) and magnetic resonance (MR) imaging are only moderately accurate in the diagnosis and local staging of bladder cancer, with cystoscopy and pathologic staging remaining the standards of reference. However, the role of newer MR imaging sequences (eg, diffusion-weighted imaging) in the diagnosis and local staging of bladder cancer is still evolving. Substantial advances in MR imaging technology have made multiparametric MR imaging a feasible and reasonably accurate technique for the local staging of bladder cancer to optimize treatment. In addition, whole-body CT is the primary imaging technique for the detection of metastases in bladder cancer patients, especially those with disease that invades muscle.

Orthotopic liver transplantation: reversible Doppler US findings in the immediate postoperative period.

Orthotopic liver transplantation (OLT) is the only definitive treatment for irreversible acute liver failure and chronic liver disease. In the immediate postoperative period after OLT, patients are closely monitored with Doppler ultrasonography (US) to detect treatable vascular complications and ensure graft survival. The first postoperative Doppler US examination is performed fairly early on the first postoperative day, before surgical wound closure has been performed. The immediate postoperative images, obtained when the effects of surgery are very recent, often reveal an array of findings that may appear alarming but that tend to normalize within a few days and are compatible with changes related to the surgery itself. These findings include a starry-sky appearance of reperfusion hepatic edema, transient foci of increased echogenicity, pneumobilia, small fluid collections, perihepatic hematomas, pleural effusion, temporary elevation of hepatic arterial velocity, transient elevation of resistive index (RI), decreased RI with tardus parvus waveform, increased portal venous flow and mono- or biphasic waveforms of the hepatic veins. Most of these changes revert to normal in the first postoperative week; deterioration atypical of transient changes requires further evaluation.

Nonalcoholic fatty liver disease.

OBJECTIVE: The inflammatory subtype of nonalcoholic fatty liver disease, nonalcoholic steatohepatitis, is becoming one of the most important causes of chronic liver disease. In this article, we discuss the epidemiology, pathogenesis, and clinical and radiologic diagnosis of the subtypes of nonalcoholic fatty liver disease. CONCLUSION: We discuss the current and evolving imaging tests in the evaluation of hepatic fatty content, inflammation, and fibrosis.

Abdominal compartment syndrome.

OBJECTIVE: The purpose of this article is to discuss the pathogenesis, clinical features, radiologic findings, and treatment of abdominal compartment syndrome, which is defined as an acute elevation of the intraabdominal pressure with organ dysfunction. CONCLUSION: Abdominal compartment syndrome is not well reported in the radiology literature. In this review, we discuss a range of CT signs such as elevated diaphragm, collapsed inferior vena cava, bowel wall thickening, bowel mucosal hyperenhancement, hemoperitoneum, and increasing abdominal girth, which, in combination, may allow the radiologist to raise the possibility of abdominal compartment syndrome.

New concepts in staging and treatment of locally advanced pancreatic head cancer.

OBJECTIVE: The objective of this article is to discuss the CT findings that guide surgeons in deciding the feasibility of tumor excision in patients with locally advanced pancreatic head cancers. CONCLUSION: Vascular resection as an adjunct to pancreaticoduodenectomy is increasingly used in pancreatic head cancer. As a result, the imaging criteria to determine which patients are candidates for potentially curative resection are evolving.

Bowel complications seen on CT after pancreas transplantation with enteric drainage.

OBJECTIVE: Bowel-related complications from pancreas transplantation account for much of the postsurgical morbidity. In a review of 98 pancreas transplant recipients, we found 19 (19.4%) with such complications. CONCLUSION: The most common problems were small-bowel obstruction and anastomotic leaks. Adhesions and internal hernias accounted for most postoperative bowel obstructions.

Postoperative doppler evaluation of liver transplants.

Doppler ultrasound plays an important role in the postoperative management of hepatic transplantation, by enabling early detection and treatment of various vascular complications. This article describes the normal Doppler findings following liver transplantation and reviews the imaging appearances of various vascular complications associated with it. The article also discusses transient waveform abnormalities, often seen on a post-transplant Doppler examination, and the importance of differentiating them from findings suggestive of ominous vascular complications.

Fetal magnetic resonance imaging.

PURPOSE OF REVIEW: Fetal magnetic resonance imaging is becoming more used in the evaluation of complex fetal abnormalities. Rapid advances in the technology and application of fetal magnetic resonance imaging necessitate a review of this subject. RECENT FINDINGS: Diffusion-weighted imaging, magnetic resonance spectroscopy and functional magnetic resonance imaging may allow assessment of fetal brain even before anatomical abnormalities are demonstrated. We discuss the uses of fetal magnetic resonance imaging in better assessment of pulmonary hypoplasia, congenital diaphragmatic hernia and renal anomalies. SUMMARY: The additional information from fetal magnetic resonance imaging, beyond that obtained by ultrasound, is invaluable in prenatal counseling, delivery planning and planning for pre- or postnatal intervention. As intrauterine and neonatal surgery evolve, so will the utilization of fetal magnetic resonance imaging.