Robert E. Bechtold

MR Enterography in the Management of Patients with Crohn Disease

Crohn disease is a complex pathologic process with an unpredictable lifelong course that includes frequent relapses. It often affects young patients, who are most vulnerable to the potential adverse effects of repeated exposure to ionizing radiation from computed tomography performed for diagnosis and surgical planning. The small intestine is the bowel segment that is most frequently affected, but it is the least accessible with endoscopic techniques. Magnetic resonance (MR) enterography has the potential to safely and noninvasively meet the imaging needs of patients with Crohn disease without exposing them to ionizing radiation. Appropriate use of MR enterography requires a carefully crafted protocol to depict signs of active inflammation as well as complications such as bowel obstruction, fistulas, and abscesses. Interpretation of MR enterographic images requires familiarity with the imaging signs and mimics of active bowel inflammation and stenosis. Although MR enterography currently is helpful for management in individual patients, the standardization of acquisition protocols and interpretive methods would increase its usefulness for more rigorous, systematic assessments of Crohn disease treatment regimens.

Assessment of rectal tumor infiltration utilizing endorectal MR imaging and comparison with endoscopic rectal sonography

The preoperative assessment of depth of invasion of rectal carcinoma is increasingly important as new treatment methodologies are developed. Accuracy of preoperative endorectal MR imaging was therefore compared with that of the endoscopic rectal sonography in determining depth of invasion of rectal carcinomas.

Ultrasonographic diagnosis of varicoceles

OBJECTIVE To assess the ability of color duplex scrotal ultrasonography to detect subclinical varicoceles and confirm the diagnosis of clinical varicoceles. DESIGN Physical examination, color duplex scrotal ultrasonography and internal spermatic venography was performed on 64 testicular units in 33 men. SETTING Male fertility center. PATIENTS Two hundred sixty-two consecutive men being evaluated for male factor infertility of whom 33 agreed to undergo venography. MAIN OUTCOME MEASURES Ultrasonographic measurement of scrotal vein diameter of patients in the supine and upright position, before and during valsalva maneuver, and scrotal vein blood flow reversal with valsalva maneuver was compared with the findings of varicocele by physical examination and venography. RESULTS The best predictor of a varicocele was internal spermatic vein diameter, and the best overall performance of ultrasonography was achieved with the patient at rest in the supine position. The best cutoff point for venous diameter for a clinical varicocele was 3.6 mm and 2.7 mm for a subclinical varicocele, but the overall accuracy was only 63%. CONCLUSIONS Confirmatory studies are needed to support the ultrasonographic diagnosis of varicoceles before considering surgical repair.

Imaging approach to staging of renal cell carcinoma.

Current imaging techniques, especially CT and MR imaging, make accurate preoperative staging of renal cell carcinoma possible. Because surgery provides the only effective therapy and because survival depends on local and distant extent, precise staging is critical for preoperative planning and prognosis. This article reviews the advantages, limitations, accuracy, and pitfalls of each of the imaging approaches to staging renal cell carcinoma, concentrating on CT and MR imaging. This information then is summarized in a suggested overall approach to staging renal cell carcinoma.

Interpretation of abdominal CT: Analysis of errors and their causes

PURPOSE Our goal was to analyze those factors contributing to the error rate in the interpretation of abdominal CT scans at an academic medical center. METHOD From a total of 694 consecutive patients (329 male, 365 female), we evaluated the error rates of interpreting abdominal CT studies. The average patient age was 54 years. All abdominal CT studies were reviewed by three to five CT faculty radiologists on the morning after the studies were performed. The error rate was correlated with reader variability, the number of cases read per day, the presence of a resident, inpatient versus outpatient, organ systems, etc. The chi 2-test was used for statistical analysis. RESULTS A total of 56 errors were found in the reports of 53 patients (overall error rate = 7.6%). Of these errors, 19 were judged to be clinically significant and 7 affected patient management. A statistically significant difference in error rates was noted among the five faculty radiologists (3.6-16.1%, p = 0.00062). No significant correlates between error rates and any of the other variables could be established. CONCLUSION The primary determinant of error rates in body CT is the skill of the interpreting radiologist.

Noninvasive assessment of portomesenteric venous thrombosis: current concepts and imaging strategies.

Rapid, noninvasive imaging strategies, especially multidetector spiral CT and CT angiography (CTA) as well as gadolinium-enhanced MR angiography (MRA), have facilitated early diagnosis of splanchnic venous thrombosis, a potentially lethal cause of intestinal ischemia. Single breath-hold volumetric acquisitions permit superior temporal and contrast resolution while eliminating motion artifact and suppressing respiratory misregistration. Increased spatial resolution is aided by thinner slice collimation. These cross-sectional imaging techniques are becoming a preferred noninvasive alternative to conventional selective mesenteric angiography with delayed imaging for venous evaluation and should be considered the primary diagnostic modalities for evaluating patients with high clinical suspicion of nonsurgical mesenteric ischemia.

Cystic changes in hepatic and peritoneal metastases from gastrointestinal stromal tumors treated with Gleevec.

AbstractBackground: Tyrosine kinase inhibitor (Gleevec or STI-571) must be considered the treatment of choice for metastatic gastrointestinal stromal tumors (GISTs). The purpose of this article is to address and illustrate a long-term follow-up of computed tomographic (CT) radiologic findings in patients with metastases from GIST after Gleevec treatment. Methods: We performed a retrospective review of seven patients (four male, three female) with unresectable metastases from GIST who were treated with STI-571 in a 1-year period. Patients were followed every 2–4 months by contrast-enhanced CT for up to 12 months. The size and attenuation of hepatic and peritoneal metastases on CT were measured and correlated. Results: Hepatic metastases from GISTs showed significant decreased attenuation from a mean of 60 HU to a mean of 32 HU (p < 0.01) in the first 2 months and continued decreasing attenuation to 23 HU at the 12-month follow-up. These metastases superficially resembled simple cysts. Most metastases became smaller, with more defined borders, after treatment. Histologic examination in a resected specimen revealed hepatic cyst with no residual tumor cells, regression of omental lesions, and extensive necrosis. Conclusions: CT findings of unresectable hepatic and peritoneal metastases from GIST displayed decreasing, near cystic attenuation and size as an effective regression in response to STI-571 treatment.

MR imaging of anterior cruciate ligament repair.

Magnetic resonance (MR) imaging is an accurate means of analyzing disruptions of the native anterior cruciate ligament (ACL). Various techniques may be used to repair a disrupted ACL. A common repair is the Macintosh lateral-substitution over-the-top repair in which a strip of fascia lata from the iliotibial band is used as a “neoligament.” The results of 27 MR examinations of 17 athletes with this repair were analyzed to determine the appearance of the neoligament on MR. Thirteen of the 17 patients had returned to full athletic activity and four were capable of strenuous activity. Examinations were made at both 0.5 and 1.5 T in varied extents of external rotation from 0 to 20°, and at variable time intervals after surgery from 1 to nearly 40 months. Only two patients clinically required postrepair arthroscopy, but both had normal repairs. Neoligaments were classified as well-defined (n = 6 studies), ill-defined (n = 10), and not discernible (n = 11), based on clarity of appearance. Reasons for this variable appearance include the variable presence of fibrous and fatty tissue investing the neoligament. We conclude that the normal neoligament, unlike the normal active ACL, has a variable appearance, including nonvisualization on MR and that criteria used in evaluating the native ligament will be inadequate to assess the repair.

Occult pneumothorax in patients with abdominal trauma: CT studies.

Abdominal CT, which routinely includes the lower thorax, is an important adjunct to supine chest radiography in detecting chest injury in patients with blunt abdominal trauma. In 1,086 consecutive patients with blunt abdominal trauma, 223 of whom had both supine chest radiography and abdominal CT, 49 patients examined with both techniques had pneumothoraces, 28 of them occult (seen only on CT). To help guide management, we established three categories of occult pneumothorax, based on size and location: (a) minuscule (<1 cm in greatest thickness, seen on four or fewer images); (b) anterior (>1 cm in greatest thickness, but not extending beyond the midcoronal line); (c) anterolateral (extending beyond the midcoronal line). In our study four of six patients with minuscule pneumothorax, including one who required mechanical ventilation, were observed without complications; two of six patients had chest tube placement. Seven of 14 cases with anterior pneumothorax were observed and resolved without complication; seven had chest tube placement. All eight patients with anterolateral pneumothoraces underwent percutaneous tube thoracostomy, regardless of proposed management. Index Terms: Pneumothorax—Trauma—Abdomen, wounds and injuries—Thorax—Computed tomography.

Extracolonic Findings at Virtual Colonoscopy: An Important Consideration in Asymptomatic Colorectal Cancer Screening

BackgroundVirtual colonoscopy has been evaluated for use as a colorectal cancer screening tool, and in prior studies, it has been estimated that the evaluation of extra-colonic findings adds