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Biomedical subjects

V Raptopoulos

Publications and source records attributed to V Raptopoulos.

At least 55 records · Page 3Linked to original sources
PubMed1997

The use of helical CT and CT angiography to predict vascular involvement from pancreatic cancer: correlation with findings at surgery.

OBJECTIVE: The purpose of this study was to test the accuracy of helical CT with and without CT angiography to predict vascular involvement from pancreatic cancer and correlate the resultant images with findings at surgery. SUBJECTS AND METHODS: Helical CT and CT angiography was done in 84 patients who had adenocarcinoma of the pancreas to refine an integrated CT angiography protocol. Of these patients 38 underwent radical pancreatoduodenectomy. Vessel integrity of the superior mesenteric artery, superior mesenteric vein, and portal vein was assessed prospectively on both axial CT scans and CT angiograms and correlated with findings at surgery and in particular with the ability of the surgeon to dissect the tumor from these vessels along the vascular planes. RESULTS: CT angiograms were obtained in 82 (98%) of 84 studies. Of the 38 patients who underwent radical pancreatoduodenectomy, resection was aborted in 11 (29%) because of vascular encasement, Compared with axial CT images, CT angiography was more accurate at revealing unresectable cases. In all but one of 11 patients with vessel encasement (narrowing of the lumen) revealed on CT angiography, the lesion was unresectable. Vessel encasement was shown in only two of these 11 patients on axial CT images (of these two patients, one underwent tumor resection). The negative predictive value of a resectable tumor was 96% for CT angiography and axial helical CT compared with 70% for axial helical CT images alone (p = .021). CONCLUSION: Helical CT with CT angiography of the pancreas provides useful information about local vascular involvement from pancreatic carcinoma. Compared with conventional axial helical CT, the addition of CT angiography improves radiologists' ability to predict the resectability of pancreatic tumors.

Adenocarcinoma↗
PubMed1997

Multiplanar helical CT enterography in patients with Crohn's disease.

OBJECTIVE: The purpose of this study was to assess the feasibility and usefulness of helical CT with multiplanar reformations in revealing complications in patients with Crohn's disease. SUBJECTS AND METHODS: Twenty-two patients with Crohn's disease and clinically suspected complications underwent helical CT enterography. The imaging protocol began with the administration of a large volume (1600 ml) of oral contrast material followed by helical scanning with axial and multiplanar two-dimensional coronal projections. Three independent observers assessed the adequacy of bowel opacification and the contribution of two-dimensional coronal projections to the interpretation of axial images. CT enterography was compared with conventional barium studies in 14 patients. Statistical analysis included repeated measures analysis of variance, the Wilcoxon signed-rank test, and the McNemar test. RESULTS: The large oral contrast medium dose was well tolerated and provided optimal bowel opacification in 21 of 22 patients. The addition of multiplanar to conventional axial images did not reveal additional abnormalities; however, multiplanar imaging significantly improved observers' confidence in their interpretation of imaging and in their assessment of the extent of bowel wall thickening (p < .01). Interobserver agreement was 78%. Findings on helical CT were comparable with those on barium studies in nine of 14 patients, superior to those on barium studies in four patients, and inferior in one patient. CONCLUSION: CT enterography is a useful technique for bowel imaging. In patients with complicated Crohn's disease, multiplanar imaging improves confidence in assessing the presence and extent of disease. CT enterography is complementary and often superior to conventional barium studies.

Adult↗
PubMed1996

Meckel's diverticulum: imaging diagnosis.

Despite the availability and wide use of modern imaging techniques, the diagnosis of Meckel's diverticulum is difficult. The signs and symptoms vary from none to those of an acute abdomen or gastrointestinal bleeding. Findings on physical examination may be inconsistent because of the variable location of the diverticulum, and bleeding may occur with no appreciable physical findings. Finally, small diverticula are often concealed by overlying small-bowel loops on routine small-bowel barium studies. The purposes of this article are to review the use of available techniques for the imaging diagnosis of Meckel's diverticulum, to discuss the relative advantages and indications for the various procedures, and to emphasize the role each plays in specific clinical circumstances. The embryology, anatomy, and clinical presentation of Meckel's diverticulum are also briefly discussed.

Humans↗
PubMed1996

Sequential helical CT angiography of aortoiliac disease.

OBJECTIVE: The purpose of this work was to study aortoiliac disease with sequential helical CT angiography. SUBJECTS AND METHODS: Sequential helical CT angiography combines two successive helical sets for data acquisition obtained during two successive bolus injections of IV contrast material and two breath-holds. Twenty-eight patients with aneurysm and 11 with occlusive disease had CT angiography. Of those 39 patients, 18 also had conventional catheter angiography. For each of the 39 patients, a CT angiogram of three segments of the aorta and 13 arteries was assessed, including the suprarenal, juxtarenal, and infrarenal aorta; celiac axis; superior and inferior mesenteric arteries; and pairs of renal, common iliac, hypogastric, external iliac, and common femoral arteries. In 18 patients undergoing both CT and conventional angiography, the appearance of these vessels was graded as occlusive (grade 0), severely stenotic (grade 1), moderately stenotic (grade 2), mildly stenotic (grade 3), normal (grade 4), ectatic (grade 5), and aneurysmal (grade 6). RESULTS: Of the 624 arteries expected to be opacified in 39 patients, 585 (94%) were actually imaged with CT angiography. In the 18 patients who had both CT angiography and catheter angiography, the two studies were in complete agreement in 243 (90%) of 269 arteries. In 13 vessels (5%), CT angiography produced an image that was one grade higher-and in 11 vessels (4%), one grade lower-than conventional angiography. In two vessels, a two-grade difference was noted. The independent readings matched on the 0-6 scale in 95% of the evaluations. An additional 5% of the readings differed by one unit. Compared with conventional angiography, CT angiography of clinically significant (> or = 85%) narrowing (grades 0 and 1) and aneurysm (grade 6) yielded sensitivity of 93%, specificity of 96%, and accuracy of 95%. CONCLUSION: Sequential helical CT angiography of the abdomen can provide sufficient vascular detail to allow evaluation of expanded vascular territories. The technique can allow accurate assessment of both stenotic and aneurysmal disease of the aorta and the iliac arteries.

Adult↗
PubMed1996

Comparison of tailored and empiric scan delays for CT angiography of the abdomen.

OBJECTIVE: Scan delays for CT angiography of the abdomen are currently individualized by matching a scan delay to the transit time of a test bolus of IV contrast material to the abdominal aorta. We sought to determine whether this procedure improves the extent and uniformity of aortic enhancement when compared with the use of a standard scan delay that is determined empirically. SUBJECTS AND METHODS: CT angiography of the upper abdomen (either the entire abdominal aorta or the aorta spanning the length of both kidneys for dedicated renal studies) was obtained in 48 patients who were considered to have normal cardiac function as determined by their referring physicians. Patients were randomized to undergo CT angiography that used either a standard scan delay of 20 or 22 sec (group 1, n = 26) or a tailored scan delay (group 2, n = 22), all other imaging parameters being identical. Tailored delays were determined by measuring contrast transit time to the abdominal aorta with software from the SmartPrep system. For each patient, aortic attenuation was measured at three different anatomic levels, and a lower threshold of 160 H was considered optimal. The number of attenuation values above this threshold, the mean attenuation, and the attenuation changes for each unit length along the abdominal aorta were then compared for the two groups of patients. RESULTS: Fifty-eight (74%) of 78 aortic attenuation values in group 1 and 55 (88%) of 69 in group 2 were above 160 H. Mean attenuation values were 192.2 H +/- 8.1 (+/-SE) in group 1 and 199.2 H +/- 10.1 in group 2. These values and the attenuation changes for each unit length along the abdominal aorta-3.7 H/cm +/- 1.7 for group 1 and 2.2 H/cm +/- 2.0 for group 2- were not significantly different. CONCLUSION: Tailoring the scan delay for CT angiography of the abdomen in patients considered to have normal cardiac function requires additional IV contrast agent, time, and patient imaging and does not improve the extent or uniformity of aortic enhancement over that obtained with a standard, empiric scan delay.

Angiography↗
PubMed1995

Lower extremity spiral CT angiography versus catheter angiography.

Both catheter and spiral computed tomography (CT) angiography of the lower extremity vasculature were performed in six patients with clinically symptomatic peripheral vascular disease. Forty-eight arteries were studied and were independently evaluated for arterial stenoses and occlusions. Compared with catheter arteriography, CT angiography correctly depicted segmental occlusions and significant stenoses (> 50%) in 26 of 28 arteries, yielding a sensitivity of 92.9%, a specificity of 96.2%, and an overall accuracy of 95.5%.

Aged↗
PubMed1995

Why perirenal disease does not extend into the pelvis: the importance of closure of the cone of the renal fasciae.

OBJECTIVE: The prevailing concept is that lack of fusion of the anterior and posterior renal fasciae caudally (an open cone) allows free communication between the perirenal space and the extraperitoneal portion of the pelvis. However, perirenal disease rarely extends into the pelvis and an open cone has not been observed on CT scans. Accordingly, we determined the anatomy of the caudal extent of the cone of the renal fasciae in cadavers and on CT scans. MATERIALS AND METHODS: Anatomic dissections of the lower portion of the retroperitoneum and the extraperitoneal portion of the pelvis were made in eight cadavers. Two cadavers were intact, two had colored latex injected into the perirenal space before dissections, and the abdomens and pelves of four were sectioned transversely in 3- to 5-cm-thick slices. The renal fasciae were traced on transparent films placed on the cross sections, and computer-generated three-dimensional representations of the tracings were made. These anatomic findings were correlated with observations made on CT scans of 59 consecutive patients with diseases involving the lower part of the retroperitoneum and the extraperitoneal portion of the pelvis (32 patients with hemorrhage, 16 with inflammatory processes, and 11 with neoplastic conditions). RESULTS: The anatomic study showed that the anterior and posterior renal fasciae merge to form a single multilaminar fascia in the iliac fossa. Anteriorly, this common fascia is loosely connected to the parietal peritoneum. Posteriorly lies the caudal continuation of the posterior pararenal compartment. This joins with the laterocaudal continuation of the central part of the retroperitoneum, which contains the iliac vessels. The distal part of the ureter lies within the caudal continuation of the single multilayered renal fascia. The CT studies done in patients showed that extension of the perirenal processes to the pelvis and vice versa was both restrained and uncommon: no direct extension of any abnormalities was observed in either direction, and laminar thickening of the fasciae was seen in one fifth of the patients. Similarly, no inferior communication of the perirenal space with the anterior or posterior pararenal spaces was seen. CONCLUSION: There is an anatomic barrier between the inferior perirenal space and the extraperitoneal pelvis formed by the fusion of the leaves of the renal fasciae into a single multilaminar fascia that acts as a barrier of disease extension. The multilaminar nature of this fascia, however, may also act as a filter, allowing some permeability between its layers. This potential interlaminar pathway is rare and is manifested as fascial thickening on CT scans. This laminar filter-barrier observation explains the lack of extension of perirenal diseases into the pelvis.

Adult↗
PubMed1995

Evaluation of necrotizing pancreatitis in the opossum by dynamic contrast-enhanced computed tomography: correlation between radiographic and morphologic changes.

BACKGROUND: The ability to quantitate the extent of acinar cell necrosis with contrast-enhanced computed tomography (CT) during acute pancreatitis is uncertain. STUDY DESIGN: Acute hemorrhagic necrotizing pancreatitis was induced in opossums by obstructing their biliopancreatic duct for up to seven days or by retrograde injection of a bile-trypsin taurocholate mixture into the opossum pancreatic duct. At selected times, groups of three animals each were examined by dynamic contrast-enhanced CT, and the abnormalities on the images were quantitated. Immediately following CT, the animals were sacrificed and the extent of necrosis was quantitated by morphometric analysis of tissue samples at the light microscope level. RESULTS: The CT severity score as well as the degree of nonenhancement on dynamic contrast-enhanced CT were both closely correlated with the extent of acinar cell necrosis (r = 0.91 and r = 0.97, respectively). CONCLUSIONS: The degree of pancreatic nonenhancement on dynamic contrast-enhanced CT can be used to quantitate the extent of pancreatic necrosis during acute necrotizing pancreatitis.

Acute Disease↗
PubMed1994

Maternal umbilicus: ultrasound window to the gravid uterus.

Transabdominal sonograms of 68 consecutive pregnant women were reviewed retrospectively. Images of fetal parts obtained through the umbilical window (UW) were compared with those obtained through the paraumbilical window (PUW) as to (1) thickness of tissue to amniotic cavity, (2) clarity of the part imaged, and (3) noise produced. The paraumbilical tissue thickness had a mean of 18 mm; the umbilical tissue thickness, a mean of 11 mm. In patients where the difference in thickness of their paraumbilical tissue and umbilical tissue was only 0 mm to 6 mm (group 1), the UW improved clarity in 10 of 34 (29%), reduced clarity in 3 of 34 (9%), and did not change clarity in 21 of 34 (62%). Improvement of images with use of the UW was not statistically significant. However, in the group of patients with the difference in tissue thickness between the paraumbilical and umbilical areas of > 6 mm (group 2), clarity was improved in 19 of 32 (60%), reduced in 2 of 32 (6%), and was unaltered in 11 of 32 (34%). In this group the image improvement with the UW was statistically significant. Images through the UW had relatively less noise. In group 1, noise was reduced in 12 of 35 (34%). The effect of the UW on noise reduction was more significant in group 2 (tissue thickness difference > 6 mm): 24 of 31 (77%) of cases.

Female↗
PubMed1994

Abdominal diffusion mapping with use of a whole-body echo-planar system.

PURPOSE: To measure apparent diffusion coefficients (ADCs) of water in liver, spleen, kidney, and muscle. MATERIALS AND METHODS: Ten volunteers (seven women and three men, aged 19-31 years [mean, 24 years]) and nine patients (five women and four men, aged 49-70 years [mean, 62 years]) (liver cyst, n = 3; liver hemangioma, n = 3; liver cirrhosis, n = 2; hepatocellular carcinoma, n = 1; and liver metastasis, n = 1) underwent magnetic resonance (MR) imaging. A stimulated-echo acquisition mode (STEAM)-type excitation and echo-planar imaging (EPI) readout was used in a 1.5-T echo-planar MR imaging system. RESULTS: ADCs measured in volunteers were liver, 1.39 x 10(-3) mm2/sec +/- 0.16; spleen, 0.95 x 10(-3) mm2/sec +/- 0.15; muscle, 1.99 x 10(-3) mm2/sec +/- 0.16; and kidney, 3.54 x 10(-3) mm2/sec +/- 0.47 (mean +/- standard deviation). Distinctive ADC values were found in organs with abnormalities. ADCs in patients with hepatic disease included liver cysts, 3.9-5.3; liver hemangiomas, 2.0-2.8; liver metastases from an islet cell tumor, 1.2; hepatocellular carcinoma, 1.7; and liver cirrhosis, 0.9-1.2 x 10(-3) mm2/sec. CONCLUSION: In vivo diffusion measurements of abdominal organs obtained with MR imaging may prove helpful in the identification and classification of abdominal disease.

Abdomen↗
PubMed1994

CT angiography: expanded clinical applications.

In this essay, the potential of vascular imaging with helical CT is explored. The speed and ease with which volumes of interest can be depicted with high resolution and the ability of CT to resolve small differences in electron density allow imaging of vascular territories with IV injection of iodinated contrast materials. Vascular and combined vascular/soft-tissue/bone imaging make CT a powerful clinical tool. The technique is predominantly used for evaluation of atherosclerotic disease of the carotid bifurcation, the renal arteries, and the major abdominal vessels. A variety of display options, such as surface rendering and maximum intensity projection (MIP), have different advantages and are often complementary. The time taken to produce clinically acceptable images has been markedly reduced to between 15 and 30 min. Some of the limitations are related to the length of vascular coverage, the contrast load, and the need for exact timing. On the other hand, the technique is not affected by flow artifacts. CT angiography is now a reliable and practical clinical test that may be a useful adjunct to conventional CT.

Angiography↗
PubMed1994

CT of the acute abdomen: findings and impact on diagnosis and treatment.

An acute abdomen is a clinical condition characterized by severe abdominal pain that develops suddenly over several hours or less [1]. Abdominal tenderness and rigidity, either generalized or localized, usually are severe and indicate an urgent need for prompt diagnosis and treatment. The underlying cause of acute abdomen varies, and some cases require immediate surgical treatment, whereas for others, surgery is unnecessary or contraindicated. This need for prompt diagnosis and treatment should not preclude an appropriate investigation to establish the precise diagnosis before undertaking surgery [1, 2].

Abdomen, Acute↗
PubMed1994

Abdominal trauma. Emphasis on computed tomography.

CT scans have been the champion in the diagnosis and management of abdominal injuries, and their use has decreased the number of negative exploratory laparotomies. Traditional areas for the use of CT scans include the assessment of injuries to the spleen and the liver and to signs of organ rupture into the peritoneal cavity. New technologic advances and increased experience have expanded the value of this modality to less than hemodynamically stable patients as well as to less common and more difficult to diagnose injuries of the pancreas, bowel, and the mesentery.

Abdominal Injuries↗
PubMed1992

Traumatic aortic tear: screening with chest CT.

Dynamic chest computed tomography (CT) was performed in 326 patients who had undergone abdominal CT for blunt trauma to evaluate the role of chest CT in screening for thoracic aortic injury. Evidence of mediastinal bleeding constituted an abnormal CT examination. The results were correlated with those from aortography in 131 patients. The chest radiographs were abnormal in 127 patients (39%). Of those 127 patients, chest CT scans were abnormal in 39 patients; an aortic tear was present in eight of those patients (21%). The remaining 88 patients had normal CT scans and no aortic injury. Of the 199 patients with normal radiographs, 15 had abnormal CT scans and 184 had normal CT scans and no aortic injury. There were no false-negative CT scans; 79% of patients with normal CT scans had false-positive chest radiographs. With CT there was a significant improvement over plain radiography in specificity, accuracy, and predictive value of positive results. If chest CT were used as an adjunct to chest radiography in the screening for traumatic aortic tear, the need for aortography would decrease by 56%. Chest CT can safely help discriminate candidates for aortography, is cost-effective, and, in hemodynamically stable patients, should be incorporated in the screening for traumatic aortic tear.

Aorta, Thoracic↗