Ultrafast 3-T MRI in the evaluation of children with acute lower abdominal pain for the detection of appendicitis.

OBJECTIVE: The purpose of this study is to evaluate the feasibility of ultrafast 3-T MRI in the evaluation of children with acute lower abdominal pain for the detection of appendicitis. SUBJECTS AND METHODS: Forty-two pediatric patients (30 girls and 12 boys; mean age, 11.5 years; age range, 4-17 years) with acute abdominal pain were prospectively studied. Ultrafast 3-T MRI was performed with a three-plane single-shot turbo spin-echo sequence and an axial T2-weighted turbo spin-echo sequence with fat suppression. All scans were performed without sedation or oral or IV contrast agent. Scan times were less than 8 minutes 45 seconds (median, 5 minutes 40 seconds). Patients underwent CT or ultrasound or both as a comparison study to the MRI examination. The MRI, CT, and ultrasound examinations were interpreted independently by four board-certified radiologists who were blinded to patient information, study interpretations, surgical pathologic findings, and final diagnosis. RESULTS: Twelve of 42 cases of acute appendicitis were detected with 100% sensitivity, 99% specificity, 100% negative predictive value, and 98% positive predictive value, all of which were statistically significant (p < 0.01). The pooled and individual receiver operating characteristic curves for radiologists' interpretation of the diagnosis of acute appendicitis were greater than 0.95 in all cases (p < 0.01) CONCLUSION: Ultrafast 3-T MRI is a feasible alternative imaging modality for the diagnosis of acute appendicitis in children, particularly in cases where ultrasound is equivocal or nondiagnostic, as an alternative to CT. Ultrafast MRI requires no sedation and no oral or IV contrast agent and has no associated radiation exposure risks.

Serial follow-up MRI of indeterminate cystic lesions of the pineal region: experience at a rural tertiary care referral center.

OBJECTIVE: The purpose of this study was to retrospectively assess the outcomes of temporal MRI follow-up of indeterminate cystic lesions of the pineal region. MATERIALS AND METHODS: Cases of indeterminate pineal lesions were identified by a computerized search of radiology reports at our institution from 1998 to 2007. Twenty-six indeterminate pineal lesions, one each in 26 patients (six males and 20 females), were followed in the current study. Cases were included in the study if the radiology report detailed an incidentally noted but indeterminate or worrisome cystic lesion of the pineal region and if temporal follow-up MRI was recommended by the interpreting neuroradiologist. For a case to be included in our data set, a follow-up MRI study must have been obtained at least 6 months after the initial study. RESULTS: Follow-up imaging ranged from 7 months to 8 years. Lesions ranged in description and appearance from "probable benign cyst" with typical cystic imaging features to "pineal mass" with features of solid enhancement. We found that, within the limitations of the technique, there were no significant changes in the size or character of any indeterminate pineal region lesion followed at our institution over the time interval of 1998-2007. CONCLUSION: In our study, all pineal lesions found incidentally and for which follow-up imaging had been recommended were stable over time. These data suggest that neoplastic lesions of the pineal region either are too rare or grow too slowly to be identified by traditional temporal imaging follow-up. With increasing interest in optimal allocation of health care resources, our findings suggest that incidentally identified pineal region cystic lesions, both typical and atypical, can be followed clinically.

Determination of etiologic mechanisms of strokes secondary to coronary artery bypass graft surgery.

BACKGROUND AND PURPOSE: Current research focused on stroke in the setting of coronary artery bypass graft (CABG) surgery has missed important opportunities for additional understanding by failing to consider the range of different stroke mechanisms. We developed and implemented a classification system to identify the distribution and timing of stroke subtypes. METHODS: We conducted a regional study of 388 patients with the diagnosis of stroke after isolated CABG surgery in northern New England from 1992 to 2000. Data were collected on patient and disease characteristics, intraoperative and postoperative care, and outcomes. Stroke etiology was classified into 1 of the following: hemorrhage, thromboembolic (embolic, thrombotic, lacunar), hypoperfusion, other (subtype not listed above), multiple (>or=2 competing mechanisms), or unclassified (unknown mechanism). The reliability of the classification system was determined by percent agreement and kappa statistics. RESULTS: Embolic strokes accounted for 62.1% of strokes, followed by multiple etiologies (10.1%), hypoperfusion (8.8%), lacunar (3.1%), thrombotic (1.0%), and hemorrhage (1.0%). There were 54 strokes with unknown etiology (13.9%). There were no strokes classified as "other." Nearly 45% (105/235) of the embolic and 56% (18/32) of hypoperfusion strokes occurred within the first postoperative day. CONCLUSIONS: We used a locally developed classification system to determine the etiologic mechanism of 388 strokes secondary to CABG surgery. The principal etiologic mechanism was embolic, followed by stroke having multiple mechanisms and hypoperfusion. Regardless of mechanism, strokes predominantly occurred within the first postoperative day.

Emerging patterns of diffusion-weighted MR imaging in Creutzfeldt-Jakob disease: case report and review of the literature.

We report the use of diffusion-weighted MR imaging in the early diagnosis and monitoring of the progression of a histopathologically proved case of sporadic Creutzfeldt-Jakob disease. Ribbon-like areas of hyperintensity in the cerebral cortex on diffusion-weighted images corresponded to the localization of periodic sharp-wave complexes on the electroencephalogram.

Intraoperative and postoperative variables associated with strokes following cardiac surgery.

BACKGROUND: Strokes are a devastating complication of coronary artery bypass grafting (CABG) surgery. Previous work from 1992 to 2000 determined the principal mechanism of strokes occurring secondary to CABG. In the present study, we quantified the association between intraoperative and postoperative variables and stroke mechanisms while adjusting for patient and disease characteristics. METHODS: We conducted a prospective study of 13,897 patients who underwent isolated CABG in northern New England from 1992 to 2000. Data were collected on patient and disease characteristics, intraoperative and postoperative care, and outcomes. Strokes were classified as embolic, hypoperfusion, and mixed (hemorrhage, lacunar, thrombotic, other, multiple, and unclassified). We quantified the association between the intraoperative and postoperative treatment and course variables and the stroke mechanism while adjusting for patient and disease characteristics. Patients without strokes served as the reference group for the determination of odds ratios (OR). RESULTS: Variables associated with embolic strokes included cardiopulmonary bypass time greater than 2 hours versus less than 1 hour (OR, 1.5; ptrend.03) and postoperative atrial fibrillation (OR, 2.4; P <.001). The risk of hypoperfusion strokes was increased with the duration of cardiopulmonary bypass (OR, 6.4; ptrend.01) and postoperative atrial fibrillation (OR, 5.4; P <.001). Postoperative atrial fibrillation was associated with the risk of mixed strokes (OR, 1.7; P =.04). CONCLUSIONS: After we adjusted for preoperative factors, postoperative atrial fibrillation and increasing duration of cardiopulmonary bypass remained significant predictors of embolic and hypoperfusion strokes, although to differing degrees. Prevention and management of atrial fibrillation and avoidance of prolonged exposure to extracorporeal circulation may offer leverage areas for the improvement of stroke outcomes.

Torsion of a lumbar nerve root schwannoma.

We report a very rare case of a lumbar nerve root schwannoma presenting with torsion and infarction. The patient was a 16-year-old male presenting with severe low back pain and urinary retention following an aggressive game of hockey. Subsequent MRI of the lumbar spine revealed a nonenhancing lumbar intradural lesion at the level of L3. The patient was taken to the operating room where he underwent a bilateral L2 and L3 laminectomy and gross total resection of an intradural nerve root tumor, which appeared to have undergone torsion and infarction. Subsequent histopathological examination of the surgical specimen verified the diagnosis of infarcted schwannoma. This is a unique case of lumbar nerve root schwannoma, with atypical MRI findings, presenting with infarction due to torsion of the involved nerve root.