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Biomedical subjects

B A Birnbaum

Publications and source records attributed to B A Birnbaum.

At least 19 recordsLinked to original sources
PubMed1996

Adrenal masses: correlation between CT attenuation value and chemical shift ratio at MR imaging with in-phase and opposed-phase sequences.

PURPOSE: To correlate attenuation values at computed tomography (CT) with signal intensity at chemical-shift magnetic resonance (MR) imaging in adrenal masses. MATERIALS AND METHODS: Thirty-eight patients with 47 adrenal lesions underwent MR imaging and unenhanced CT examinations. MR examinations, performed at 1.5 T, included T1-weighted imaging with fat and water in phase and gradient-echo imaging with fat and water out of phase (repetition time, 45-180 msec; echo time, 1.4-3.1 msec). Lesion-to-spleen signal intensity ratios were calculated for the in-phase and opposed-phase images. The chemical-shift ratio, a measure of signal intensity loss between in-phase and opposed-phase images, and the CT attenuation value (in Hounsfield units) were determined for each lesion. RESULTS: A statistically significant correlation (0.85) was found between attenuation and chemical-shift-ratio values (P < .000001). Attenuation in six benign lesions was within 2 standard deviations of the mean attenuation in malignant lesions, and the chemical-shift ratio in eight benign lesions was within 2 standard deviations of the mean chemical-shift ratio in malignant lesions. Six of these eight lesions were misclassified on the basis of both attenuation and chemical-shift-ratio values. CONCLUSION: CT attenuation values are highly correlated with chemical-shift ratios. Both values were indeterminate for a similar subset of benign lesions.

Adrenal Gland Neoplasms↗
PubMed1996

Multiphasic renal CT: comparison of renal mass enhancement during the corticomedullary and nephrographic phases.

PURPOSE: To evaluate thin-section computed tomography (CT) performed during the corticomedullary and nephrographic phases of contrast material enhancement in the characterization of renal masses. MATERIALS AND METHODS: A prospective study of 30 patients was undertaken with CT to characterize 31 "indeterminate" renal masses. In all patients, 5-mm-thick, contiguous, high-tube-current (320-340-mA) scans were obtained through the kidneys before (axial mode), during (helical mode, 25-second delay, corticomedullary-phase images), and after (axial mode, 120-second delay, nephrographic-phase images) administration of a 117-second biphasic injection of intravenous contrast material. RESULTS: Eight of 16 neoplasms measured less than 20 HU on CT scans obtained without contrast material enhancement; measurements of two of these corresponded to "cyst attenuation" during the corticomedullary phase. Enhancement of 10 HU or greater was demonstrated in 11 neoplasms during the corticomedullary phase and in all neoplasms in the nephrographic phase. No enhancement was seen in 15 radiologically benign cysts. Both renal neoplasms and normal renal cortex demonstrated significantly greater enhancement in the nephrographic phase compared with that in the corticomedullary phase (P = .0002 and P < .0001, respectively). CONCLUSION: Enhancement of renal neoplasms is time dependent and may not be evident in hypovascular tumors analyzed during the early corticomedullary phase. Reliance on absolute CT attenuation measurements, without use of internal standards as controls, may lead to misdiagnosis of neoplasms as cysts.

Adult↗
PubMed1996

Heterotopic ossification of midline abdominal incisions: CT and MR imaging findings.

OBJECTIVE: Heterotopic ossification of a midline surgical incision in a form of myositis ossificans traumatica in which osseous, cartilaginous, and, occasionally, myelogenous elements develop within an abdominal wound. When large amounts of internal ossification are present, the scar may demonstrate a complex radiologic appearance and potentially may be misinterpreted as a retained foreign body or incisional neoplastic recurrence. This report describes the CT and MR imaging findings of this entity. SUBJECTS AND METHODS: The authors retrospectively reviewed the cross-sectional imaging findings of 11 patients with ossified midline abdominal wounds. All but one of the patients were men, and the median age at diagnosis was 40 years old (range, 20-76 years old). Initial imaging was performed 7 days to 36 months after surgery (mean, 6.7 months). CT and MR imaging scans were reviewed, and lesion size, location, distance from the xiphoid, shape, and stability were assessed. Pathologic proof was obtained in one patient. RESULTS: CT and MR imaging examination in all patients showed ossified surgical scars, with the attenuation or signal intensity of the ossified components equivalent to that of the spine. Intralesional, fat-density components suggestive of marrow were present in two patients. All scars were located in the upper abdomen between the anterior abdominal fascia and the peritoneal surface, at the level of or inferior to the xiphoid process. Scars ranged in length from 0.7 to 13.4 cm (mean, 6.9 cm). Distances from the inferior tip of the xiphoid to the superior aspect of the ossified scar ranged from 0 to 4.9 cm (mean, 2.2 cm). Time from surgery to the initial postoperative demonstration of scar ossification ranged from 11 days to 36 months (mean, 6.8 months). None of the five patients who underwent preoperative CT examinations had abnormalities in the location of subsequent scar ossification. Of the nine patients with multiple postoperative examinations, scar size and appearance remained stable in six. In the remaining three patients, scar size was stable but showed progressive internal ossification. CONCLUSION: Heterotopic ossification within midline abdominal scars can be diagnosed by both CT and MR imaging examination. Recognition of the imaging appearances of such ossification should help prevent diagnostic confusion when attending postoperative patients.

Abdominal Muscles↗
PubMed1995

CT of inflammatory disease of the colon.

CT plays an important role in the evaluation of patients with suspected colonic inflammation. High-resolution, thin-section imaging of the gastrointestinal tract allows assessment of both the intraluminal and extraluminal components of colonic disease, thereby enabling radiologists to detect and stage colonic pathology accurately. In addition, CT can be used to guide percutaneous drainage of abscess collections, often obviating the need for surgical intervention. This article describes CT techniques for diagnosing inflammatory diseases of the colon as well as the typical CT appearances.

Appendicitis↗
PubMed1995

Glutaraldehyde colitis: radiologic findings.

PURPOSE: Two percent glutaraldehyde on colonic mucosa may result in a toxic colitis, and the clinical features may mimic those of colonic ischemia. The study was performed to determine the radiologic appearance of glutaraldehyde-induced toxic colitis. MATERIALS AND METHODS: A retrospective review was performed with the clinical and imaging findings in four patients with glutaraldehyde-induced colitis seen during a 6-year period. RESULTS: Patients developed a self-limited syndrome of cramps and abdominal pain, tenesmus, and rectal bleeding within 48 hours of uncomplicated sigmoidoscopy or colonoscopy. Sample cultures excluded enteric pathogens. Computed tomography (CT) demonstrated circumferential thickening of the colonic wall in a left-sided distribution in all patients. Heterogeneous mural enhancement (target-sign appearance) was noted in two patients. Follow-up CT studies confirmed resolution of mural wall thickening with conservative management. CONCLUSION: The clinical and radiologic features of glutaraldehyde-induced toxic colitis may mimic those of colonic ischemia. This complication should be suspected in patients who develop hemorrhagic colitis immediately after undergoing colonoscopy.

Adult↗
PubMed1995

Small renal parenchymal neoplasms: further observations on growth.

PURPOSE: To determine the growTH rate and behavior of small (< or = 3.5-cm diameter) incidentally detected renal parenchymal neoplasms. MATERIALS AND METHODS: Forty renal parenchymal tumors in 37 adult patients (mean age, 65.5 years) were observed with computed tomography (CT) and ultrasound for 1.75-8.5 years (mean, 3.25 years). Surgical removal was performed of 26 tumors proved and graded at pathologic examination. Fourteen tumors with CT criteria of neoplasm are being followed up. RESULTS: The overall growth rate of neoplasms was 0-1.1 cm/y (mean, 0.36 cm/y). Thirty tumors grew 0.5 cm/y or less and 19 grew very slowly (< or = 0.35 cm/y). No patient developed metastatic disease. Nine (24%) had multiple neoplasms. CONCLUSION: Most small, incidentally discovered, well-marginated renal parenchymal neoplasms grow slowly and are not an immediate threat to a patient's life. Watchful waiting might be appropriate instead of surgical removal, especially in patients who are elderly or may not survive surgery.

Adenoma↗
PubMed1995

Hepatic enhancement during helical CT: a comparison of moderate rate uniphasic and biphasic contrast injection protocols.

OBJECTIVE: The purpose of this study was to compare the degree and timing of peak hepatic enhancement, optimal scanning intervals, and optimal delay times of moderate-rate uniphasic and biphasic contrast material injection protocols for hepatic helical CT. MATERIALS AND METHODS: One hundred fifty patients were randomized into three injection protocols, receiving 42.3 g iodine (150 ml iothalamate meglumine) delivered using 3 ml/sec uniphasic, 2 ml/sec uniphasic, or biphasic (3 ml/sec [50 ml], 1 ml/sec [100 ml]) technique. Statistically fitted aortic and hepatic enhancement curves were generated from dynamic incremental CT data for each patient. Protocols were compared by maximum hepatic enhancement, and contrast enhancement indices were modeled for a 38-sec helical acquisition. RESULTS: The 3 ml/sec and 2 ml/sec uniphasic protocols produced higher peak hepatic enhancement (64 +/- 15 H and 62 +/- 15 H [mean +/- 1 SD]) than the 3 ml/sec biphasic protocol (52 +/- 10 H; p < .001). Contrast enhancement indices for the 3 ml/sec uniphasic and 2 ml/sec uniphasic protocols (385 +/- 398 H/sec and 397 +/- 412 H/sec) were significantly greater than the index for the 3 ml/sec biphasic protocol (123 +/- 194 H/sec; p < .0001) at a 50-H threshold. Optimal scan delay times were 50 +/- 8, 75 +/- 7, and 119 +/- 8 sec, respectively, for the 3 ml/sec uniphasic, 2 ml/sec uniphasic, and 3 ml/sec biphasic techniques. CONCLUSION: The moderate-rate uniphasic injections studied provided greater hepatic enhancement throughout the helical acquisition without requiring the prohibitively long delay time necessitated by the moderate-rate biphasic injection. These findings differ from prior results that showed that a uniphasic injection may provide comparable levels of hepatic enhancement when compared with a high-flow-rate biphasic injection.

Adult↗
PubMed1994

Acute appendicitis: CT and US correlation in 100 patients.

PURPOSE: To compare the accuracy of computed tomography (CT) and ultrasonography (US) in the diagnosis of acute appendicitis. MATERIALS AND METHODS: One hundred consecutive patients were examined with US and CT, and the results, independently reported, were correlated with surgical and histopathologic findings (69 patients) and data from other laboratory and clinical follow-up (31 patients). RESULTS: Fifty-four patients had acute appendicitis; 46 patients did not. Analysis of the data for CT and US, respectively, revealed sensitivity, 96% versus 76%; specificity, 89% versus 91%; accuracy, 94% versus 83%; positive predictive value, 96% versus 95%; and negative predictive value, 95% versus 76%. In the 46 patients without appendicitis, an alternative diagnosis was made with CT in 22 patients and with US in 15. CT scans showed abscesses and/or phlegmons in 28% of patients with appendicitis versus 17% at US. Results of CT and US were discordant in 20 patients; CT findings were correct in 17 and US findings in three. CONCLUSION: CT is more accurate than US in diagnosis of acute appendicitis.

Acute Disease↗
PubMed1994

CT of appendicitis and diverticulitis.

CT scans have made a significant impact on the diagnosis and staging of those gastrointestinal disorders that are associated with perienteric inflammatory extension. Appendicitis and diverticulitis are examples of such diseases, and this article reviews the current role of CT scans in the diagnosis and management of patients with these conditions.

Acute Disease↗
PubMed1993

Graphical interface for medical image processing.

We have developed a graphical interface which allows users of varying levels of computer experience and proficiency to manipulate medical image-processing data with "point-and-click" ease. The power which had formerly been associated with protocols and shell scripts has been combined with the flexibility and "user-friendliness" of buttons and dialog boxes.

Computer Graphics↗
PubMed1992

Closed-loop and strangulating intestinal obstruction: CT signs.

In 19 patients with closed-loop intestinal obstruction, including 16 patients with strangulating obstruction, the findings at examination with computed tomography (CT) were retrospectively correlated with the surgical and pathologic findings and evaluated by two radiologists. Signs of closed-loop obstruction, present in 15 patients, were associated with the configuration of the incarcerated loop of small bowel, abnormalities detected at the site of obstruction, or both. These abnormalities were the following: a U-shaped, distended, fluid-filled bowel loop; the whirl sign; the beak sign; a triangular loop; two adjacent collapsed loops of bowel at the site of obstruction; or all of these. CT signs of strangulation, seen in 10 of the 16 patients with ischemic or infarcted bowel, were associated with the appearance of the bowel wall (thickening, high attenuation, and the target sign), abnormalities in the attached mesentery, or both. In mechanical obstruction of the small bowel, detection of ischemic changes in the bowel wall or mesentery with CT indicates strangulation. Absence of CT findings of ischemia or infarction does not rule out strangulation.

Adult↗
PubMed1992

High-attenuation lymphadenopathy in AIDS patients: significance of findings at CT.

A retrospective evaluation was performed of the location and attenuation characteristics of abdominal and pelvic lymphadenopathy, identified at dynamic sequential bolus computed tomography (CT) in 69 patients with acquired immunodeficiency syndrome (AIDS). Lymph node appearance at CT was characterized as hyperattenuating, isoattenuating, or hypoattenuating relative to the iliopsoas muscle. The significance of finding hyperattenuating adenopathy in the patient population was evaluated. Thirty-three patients had hyperattenuating adenopathy, including 26 with the epidemic form of Kaposi sarcoma (KS). Of 38 patients with epidemic KS, 26 had hyperattenuating, 11 had isoattenuating, and one had hypoattenuating lymphadenopathy. The positive predictive value of hyperattenuating adenopathy for epidemic KS was 79%. These findings were statistically significant at the 95% confidence interval (P < .005). Hyperattenuating lymphadenopathy, identified on dynamic sequential bolus CT scans in AIDS patients, was seen with disseminated KS in approximately 80% of cases.

AIDS-Related Opportunistic Infections↗
PubMed1991

Asymmetry of the renal nephrograms on CT: significance of the unilateral prolonged cortical nephrogram.

The finding of asymmetry in the renal nephrograms as manifested by a unilateral prolonged cortical nephrogram on dynamic contrast-enhanced CT examinations signifies the presence of an abnormality of renal parenchymal perfusion and/or tubular transit. The differential diagnostic possibilities include stenosis or long-standing occlusion of the renal artery, renal vein thrombosis, and urinary tract obstruction.

Humans↗