Biomedical subjects

A J Megibow

Publications and source records attributed to A J Megibow.

At least 19 recordsLinked to original sources

PubMed1995

Pancreatic adenocarcinoma: CT versus MR imaging in the evaluation of resectability--report of the Radiology Diagnostic Oncology Group.

PURPOSE: To compare findings with computed tomography (CT) and magnetic resonance (MR) imaging in pancreatic adenocarcinoma and to determine optimal pulse sequences for MR imaging. MATERIALS AND METHODS: CT scans and MR images were compared of 189 adult patients with known or suspected adenocarcinoma of the pancreas. Levels of confidence were correlated with surgical and pathologic results. RESULTS: The accuracy of CT was 0.73 and of MR imaging was 0.70. The negative predictive value of CT was 0.28 and of MR imaging was 0.23. The positive predictive value of CT was 0.89 and of MR imaging was 0.88. Gradient-echo and T1-weighted spin-echo sequences ranked equally in evaluation of vascular invasion, T1-weighted spin-echo sequences were preferred for assessing lymphadenopathy, and T2-weighted spin-echo sequences were preferred for detecting hepatic metastases. CONCLUSIONS: Cross-sectional imaging modalities are useful in the identification of unresectable pancreatic carcinoma. CT is recommended for initial imaging assessment.

Adenocarcinoma↗

PubMed1995

CT in patients with scirrhous carcinoma of the GI tract: imaging findings and value for tumor detection and staging.

OBJECTIVE: The purposes of this study were to analyze the CT features of scirrhous carcinoma of the gastrointestinal (GI) tract and to assess the usefulness of CT in detecting and staging these lesions. MATERIAL AND METHODS: This is a retrospective evaluation of 31 proven cases of scirrhous carcinoma (linitis plastica) of the GI tract imaged in our institution from 1986 to 1994. Twenty-two patients had primary gastric carcinoma, and nine had carcinoma of the colon (rectosigmoid in eight and right colon in one). CT examinations were reviewed and correlated with pathologic and/or surgical findings in all patients and with barium examinations in 19 cases. A modified Dukes classification was used to stage these lesions without knowledge of the pathologic and surgical results. RESULTS: Four gastric lesions were missed during the initial CT examination. Seventeen patients had extensive circumferential lesions, and five had focal plaquelike lesions. The wall thickness ranged from 1 to 3 cm (mean, 1.8 cm). Homogeneous enhancement was seen in 17 patients, slightly heterogeneous enhancement was seen in one, a target configuration was present in two patients, and intramural calcification was present in one patient. All colonic lesions were circumferential, homogeneously enhancing with a wall thickness ranging from 1 to 3 cm (mean, 2 cm). CT scans showed limitations in evaluating local parameters. Compared with surgical and pathologic staging, CT correctly staged 26 patients, understaged four patients, and overstaged one patient. Among the 19 patients with pathologically proven stage D lesions (61%), CT correctly staged 17 patients (89%) and had a 100% positive predictive value. One case of hepatic metastases, 13 cases of malignant ascites, and 11 cases of omental and peritoneal metastases were found. CONCLUSION: CT is an important complimentary imaging technique to detect scirrhous carcinoma. The sensitivity of detection depends on the size of the lesion and the quality of the examination. CT has limitations in staging early lesions but shows a high sensitivity (89%) in detecting Dukes stage D lesions. Accurate CT staging in these individuals (61% in this series) allows a more adequate treatment strategy and avoids unnecessary exploratory laparotomies.

Adenocarcinoma, Scirrhous↗

PubMed1995

Value of CT in the diagnosis and management of patients with suspected acute small-bowel obstruction.

OBJECTIVE: The purpose of this prospective study was to evaluate the role of CT in the diagnosis of patients with suspected acute small-bowel obstruction in whom clinical and plain radiographic findings were inconclusive. SUBJECTS AND METHODS: Fifty-seven nonconsecutive patients with suspected acute small-bowel obstruction were referred for CT to differentiate small-bowel obstruction from ileus (33 patients) or to establish the cause of obstruction (24 patients). The final diagnosis was established either by surgery (42 patients) or by the clinical evolution (15 patients). The change in the prescan diagnosis as to the presence, cause, and severity (strangulation) of small-bowel obstruction made on the basis of the CT findings was noted. Finally, the changes in therapy resulting from the CT information were recorded. RESULTS: CT correctly distinguished between small-bowel obstruction and ileus in all cases except one. CT enabled us to modify an erroneous clinical diagnosis correctly in 12 (21%) of 57 cases, including eight cases for which pre-CT diagnosis was ileus and four cases for which pre-CT diagnosis was small-bowel obstruction. CT allowed us to predict the cause of obstruction correctly in 33 (85%) of 39 patients with confirmed small-bowel obstruction but it failed to differentiate adhesions from internal hernias and radiation enteritis. The pre-CT diagnosis of the cause of obstruction was correctly changed because of CT findings in 17 (44%) of 39 patients with subsequently proved small-bowel obstruction. CT was able to identify strangulation in nine of the 12 patients with proved strangulation, which altered the pre-CT diagnosis in three patients. CT findings correctly modified the management in 12 (21%) of 57 patients, by changing either a conservative management to an operative one in 10 (18%), or an operative to a conservative one by differentiating ileus from obstruction in two patients. CONCLUSION: Our findings show that CT is a valuable diagnostic procedure in patients with suspected acute small-bowel obstruction. CT not only is useful in distinguishing obstruction from paralytic ileus, but it frequently establishes the cause of the obstruction and the presence of strangulation. CT findings lead to decisions to treat patients surgically in a significant number of patients.

Acute Disease↗

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

Bowel obstruction. Evaluation with CT.

Recently, CT scans have proved to be useful in revealing the site, level, and cause of bowel obstruction and in displaying signs of threatened bowel viability. This article outlines the utility of CT scans, both in terms of the diagnostic features of bowel obstruction and in the evaluation of its accuracy.

Contrast Media↗

PubMed1993

Histoplasmosis of the colon in patients with AIDS: imaging findings in four cases.

OBJECTIVE: The purpose of this study was to describe and illustrate the radiographic findings of colonic histoplasmosis in patients with AIDS. SUBJECTS AND METHODS: Four HIV-positive patients were admitted because of fever, abdominal pain, tenderness, weight loss, and diarrhea. One patient had known disseminated histoplasmosis, one had esophageal moniliasis, and two had no other known opportunistic infections or tumors. All four patients had barium enemas, and two had abdominal CT examinations. The diagnosis was established via colonoscopic biopsy in three patients and with surgery in one patient. RESULTS: Barium enema in two patients showed separate, short, apple-core lesions in the transverse and descending colon. In one patient, a single lesion in the ascending colon mimicked colonic carcinoma. One patient had segmental involvement of the ascending colon, compatible with inflammatory bowel disease. CT examination revealed circumferential thickening of the wall of the colon with adjacent lymphadenopathy of mixed attenuation. Three patients responded to medical therapy, and one patient remained symptomatic and was found on a follow-up CT examination to have significant recurrence of retroperitoneal lymphadenopathy. CONCLUSION: Colonic histoplasmosis in patients with AIDS has protean radiographic features and can mimic colonic carcinoma. In these patients, histoplasmosis should be part of the differential diagnosis, particularly when several colonic lesions are detected, associated regional and retroperitoneal lymphadenopathy is present, and the patient is living or has lived in an endemic area.

AIDS-Related Opportunistic Infections↗

PubMed1992

Pancreatic adenocarcinoma: designing the examination to evaluate the clinical questions.

The dynamic incremental bolus technique and modifications in slice thickness can be used to tailor current computed tomographic (CT) technology to evaluate the extent of pancreatic cancer. Contrast material administered intravenously allows visualization of small lesions, an assessment of vascular invasion versus patency, and maximal conspicuity and detectability of hepatic metastases. CT findings in 104 cases of pancreatic cancer studied during 1979-1982 (group A) were compared with findings in 107 cases of pancreatic cancer studied during 1984-1987 (group B). Masses in the body and tail of the pancreas were recognized in 96% (n = 103) of cases in group B and 89% (n = 93) in group A. Masses in the head of the gland were detectable in 94% (n = 101) of cases in group B and 76% (n = 79) of cases in group A. Hypoattenuating tumors were detectable in 78% (n = 83) of cases in group B, as opposed to 24% (n = 25) in group A. CT is the primary diagnostic technique in the evaluation of pancreatic adenocarcinoma.

Acute Disease↗

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↗

PubMed1991

Appendicitis: prospective evaluation with high-resolution CT.

Computed tomography (CT) was used to prospectively evaluate 100 patients with clinical indications for acute appendicitis. Examinations were performed with the terminal ileum and cecum filled with contrast material. Acute appendicitis was diagnosed when an abnormal appendix or inflammatory changes plus an appendicolith were detected. Failure to visualize an abnormal appendix or appendicolith in the presence of pericecal inflammatory changes was considered suspicious but nonspecific. CT results were correlated with surgical and pathologic results (74 patients) and other radiologic and clinical findings (26 patients). CT helped to diagnose appendicitis (64 patients) and nonspecific right lower quadrant inflammation (five patients) and to rule out appendicitis (31 patients). CT had a 98% sensitivity, an 83% specificity, and a 93% accuracy. In 17 of 31 patients without CT evidence of appendicitis, other conditions explaining their symptoms were detected. When the clinical diagnosis is in doubt, CT can be used successfully to evaluate patients with acute appendicitis.

Acute Disease↗

PubMed1991

Bowel obstruction: evaluation with CT.

Eighty-four computed tomographic (CT) scans from patients referred for bowel obstruction between January 2, 1988, and December 31, 1989, were retrospectively evaluated. A pair of radiologists without knowledge of patient histories determined the presence or absence of bowel obstruction. Sixty-four patients ultimately proved to have intestinal obstruction, and 20 did not. Diagnosis was established by means of surgery (n = 39), barium studies (n = 17), and clinical course (n = 28). Causes of obstruction included adhesions (n = 37), metastases (n = 6), primary tumor (n = 7), Crohn disease (n = 4), hernia (n = 3), hematoma (n = 2), colonic diverticulitis (n = 2), and other (n = 3). In addition, 83 CT examinations in patients with no history or indication of intestinal obstruction were simultaneously reviewed. The overall sensitivity was 94%, specificity was 96%, and accuracy was 95%. The cause of obstruction was correctly predicted in 47 of 64 cases (73%). Intestinal obstruction was not diagnosed in any of the 83 control patients. CT is most useful in patients with a history of abdominal malignancy and in patients who have not been operated on and who have signs of infection, bowel infarction, or a palpable abdominal mass.

Barium Sulfate↗

PubMed1991

Hepatic hemangiomas: diagnosis with fusion of MR, CT, and Tc-99m-labeled red blood cell SPECT images.

A method of image analysis was developed for correlation of hemangiomas detected at computed tomography (CT) and/or magnetic resonance (MR) imaging with increased blood pool activity evident at single photon emission CT (SPECT) performed after labeling of red blood cells with technetium-99m. Image analysis was performed in 20 patients with 35 known hepatic hemangiomas. After section thickness and pixel sizes of the different studies were matched, intrinsic landmarks were chosen to identify anatomically corresponding locations. Regions of interest (ROIs) drawn on the CT and/or MR images were translated, rotated, and reprojected to match the areas of interest on the corresponding SPECT images by means of a two-dimensional polynomial-based warping algorithm. Analysis of ROIs on 30 SPECT-MR and 20 SPECT-CT pairs of registered images provided absolute confirmation that 34 suspected hemangiomas identified on SPECT images correlated exactly with lesions seen on CT and/or MR images. Accuracy of fusion was within an average of 1.5 pixels +/- 0.8 (+/- 1 standard deviation). The technique enabled diagnostic confirmation of hemangiomas as small as 1.0 cm and proved useful for evaluating lesions located adjacent to intrahepatic vessels.

Adult↗

PubMed1990

Extrapulmonary Pneumocystis carinii infection in AIDS: CT findings.

Clinical and computed tomographic (CT) findings in three cases of extrapulmonary Pneumocystis carinii infection in patients with acquired immunodeficiency syndrome (AIDS) were reviewed. Proved sites of involvement included the spleen (n = 2), bone marrow (n = 1), liver (n = 1), and peritoneal and pleural fluid (n = 1). CT findings included focal low-attenuation splenic lesions that became progressively calcified in rimlike or punctate fashion; punctate calcifications in the liver, renal cortices, and adrenal glands; calcification of lymph nodes; and pleural and peritoneal effusions with subsequent calcifications of the pleural and peritoneal surfaces. Although rare both before and since the onset of the AIDS epidemic, extrapulmonary P carinii infection in AIDS patients has been reported with increasing frequency in recent years, and more cases with radiologic manifestations should be expected.

Acquired Immunodeficiency Syndrome↗

PubMed1990

Acute pancreatitis: value of CT in establishing prognosis.

The presence and degree of pancreatic necrosis (30%, 50%, or greater than 50%) was evaluated by means of bolus injection of contrast material and dynamic sequential computed tomography (CT) in 88 patients with acute pancreatitis at initial and follow-up examinations. Pancreatic necrosis was defined as lack of enhancement of all or a portion of the gland. Length of hospitalization, morbidity, and mortality in patients with early or late necrosis (22 patients) were evaluated and compared with the same criteria in the rest of the group. Patients with necrosis had a 23% mortality and an 82% complication rate; patients without necrosis had 0% mortality and 6% morbidity. When only the initial assessment was considered, patients with peripancreatic phlegmons and necrosis had 80% morbidity, compared with 36% morbidity in those with phlegmons and no necrosis. Serious complications occurred in patients who initially had or developed more than 30% necrosis. A CT severity index, based on a combination of peripancreatic inflammation, phlegmon, and degree of pancreatic necrosis as seen at initial CT study, was developed. Patients with a high CT severity index had 92% morbidity and 17% mortality; patients with a low CT severity index had 2% morbidity, and none died.

Abscess↗

PubMed1990

Definitive diagnosis of hepatic hemangiomas: MR imaging versus Tc-99m-labeled red blood cell SPECT.

Thirty-seven patients with 69 suspected hemangiomas found by means of computed tomography (CT) and/or ultrasound were studied with both 0.5-T magnetic resonance (MR) imaging and single photon emission CT (SPECT) with technetium-99m-labeled red blood cells. Using a criterion of "perfusion-blood pool mismatch," SPECT readers diagnosed 50 of 64 hemangiomas and all five "nonhemangiomas" (sensitivity, 78% [95% confidence interval, 0.664 - 0.864]; accuracy, 80% [0.69 - 0.877]). Qualitative analysis of lesion signal intensity on T2-weighted spin-echo MR images allowed readers to diagnose 58 of 64 hemangiomas and four of five nonhemangiomas (sensitivity, 91% [0.814 - 0.96]; accuracy, 90% [0.807 - 0.951]). Because of the significantly higher cost of MR imaging and its inability to categorically differentiate hemangiomas from hypervascular metastases, the authors consider SPECT to be the method of choice for diagnosing hepatic hemangiomas. MR imaging should be reserved for the diagnosis of lesions smaller than 2.0 cm and for those 2.5 cm and smaller adjacent to the heart or major hepatic vessels; in such cases MR imaging was found superior to SPECT.

Adult↗

PubMed1990

Observations on the growth of renal neoplasms.

A retrospective review of the imaging results of 11 patients with 13 solid renal parenchymal neoplasms was performed, allowing analysis of the linear growth rates of these tumors. The study sample included seven pathologically proved renal adenocarcinomas and six lesions that were indicative of a neoplasm radiologically (enhancing parenchymal mass on computed tomographic [CT] scans with documented interval growth), which were followed up for 2-7.8 years. Variable interval tumor growth was demonstrated in every case except one and ranged from 0 to 1.6 cm/y, with an overall mean linear growth rate of approximately 0.5 cm/y. Ten of 11 "small renal neoplasms" (less than or equal to 3.0 cm in diameter) displayed interval growth, with five ultimately measuring greater than 3.0 cm (size range, 3.5-7.0 cm). While the results are preliminary and reflect observations on a very small study sample, it was noted that five of the seven pathologically proved adenocarcinomas appeared homogeneous and well marginated, and all were low-grade, low-stage carcinomas. These grew more slowly and were generally smaller at initial presentation than higher-grade lesions, which demonstrated a more heterogeneous appearance on CT scans.

Carcinoma, Renal Cell↗

PubMed1990

Visceral and nodal calcification in patients with AIDS-related Pneumocystis carinii infection.

Clinical and radiologic findings in nine patients with AIDS and disseminated Pneumocystis carinii infection were analyzed retrospectively. The diagnosis was confirmed by autopsy (five patients) and by biopsy (two patients). All nine had a history of P. carinii pneumonia. CT showed parenchymal calcifications in the spleen (seven patients), liver (six patients), kidneys (six patients), abdominal lymph nodes (three patients), adrenal glands (two patients), and mediastinal lymph nodes (one patient). Multiple punctate calcifications in the liver, spleen, kidneys, and/or adrenal glands were visible on plain films in three patients. Sonography showed diffuse tiny echogenic foci without shadowing in the liver, spleen, and kidneys. In one patient, CT showed multiple hypodense lesions in the spleen. P. carinii infection should be included in the differential diagnosis when calcifications or focal lesions are detected at one or more extrapulmonary sites in an immunodeficient patient, even if there is no history or evidence of P. carinii pneumonia.

Acquired Immunodeficiency Syndrome↗