Helical (spiral) CT of the abdomen

Helical CT and CT angiography for the identification of crossing vessels at the ureteropelvic junction

In comparison with pyeloplasty, endourologic procedures for the treatment of ureteropelvic junction obstruction offer good success rates with less morbidity and a shorter hospitalization; however, studies have found lower success rates and increased complications in patients with crossing vessels. Conventional diagnostic angiography and intravenous urography have both been used to identify crossing vessels at the UPJ; but, a reliable, less invasive, less costly, and simpler preoperative procedure to identify crossing vessels is needed. Helical CT with CT angiography is a promising noninvasive technique for the identification of crossing vessels at the ureteropelvic junction, which can be used for surgical planning of endourologic treatment of UPJ obstruction.

Gastric cancer: evaluation of triphasic spiral CT and radiologic-pathologic correlation

PURPOSE

The purpose of this study was to evaluate the utility of triphasic spiral CT with water-filling method in the preoperative T staging of gastric cancer.

METHOD

We performed triphasic spiral CT in 108 patients with gastric cancer (53 with early and 55 with advanced gastric cancer). The CT findings were prospectively analyzed and correlated with the histopathologic findings. Spiral CT scans were assessed for the layered pattern of the normal gastric wall, the detectability of tumor, the enhancing pattern of the tumor, and the depth of tumor invasion.

RESULTS

The layered pattern of the normal gastric wall was clearly demonstrated in the arterial-dominant or parenchymal phase. All 12 early cancers detected with spiral CT were most clearly depicted in the arterial-dominant or parenchymal phase. On the other hand, 15 (28%) of 54 advanced cancers were most clearly depicted in the equilibrium phase due to the gradual enhancement from the inner mucosal side of the tumor. Most of these tumors were scirrhous type tumor containing abundant fibrous tissue stroma. The accuracy of spiral CT for tumor detection and T staging was 98 and 82%, respectively, in advanced gastric cancer and 23 and 15%, respectively, in early gastric cancer.

CONCLUSION

Spiral CT with triphasic scan technique improved the accuracy of estimating the depth of tumor invasion in advanced gastric cancer.

Utility of low mA 1.5 pitch helical versus conventional high mA abdominal CT

The objective of this study was to evaluate the utility of a low mA 1.5 pitch helical versus conventional high mA conventional technique in abdominal computed tomography (CT). Twenty-five patients who had both a conventional high mA (> 300) and a 1.5 pitch low mA (80-125) helical CT within 3 months were selected for inclusion in the study. Patients were excluded who had a significant change in pathology between the two studies. The other parameters (injection rate, contrast type and volume, and filming window/level) were constant. The studies were randomized and blinded to five separate experienced readers who graded the studies by a variety of normal anatomical structures and pathological criteria. Overview questions also assessed noise, resolution, contrast, and overall quality. The abdominal wall/retroperitoneum and hiatal hernias were statistically better visualized on the conventional high mA studies. However, for all other normal anatomical and pathological sites, there was equivalent or better visualization on the helical versus the conventional CT examinations. The resolution of the helical studies was graded statistically better than the high mA conventional CT scans as was the amount of noise present on the images. While there was some advantage for conventional high mA CT with respect to contrast enhancement and low contrast sensitivity, these differences were not statistically significant. It appears from the data of this study that a low mA technique in evaluating the abdomen may be a useful option in performing routine abdominal CT. The radiation dose savings to the patient is significant and there appears to be little degradation of image quality using a low mA 1.5 helical versus mA conventional CT technique.

Regeneration of the un-embolized liver parenchyma following portal vein embolization

BACKGROUND/AIMS

Portal vein embolization (PVE) induces atrophy of the embolized hepatic parenchyma and hypertrophy of the un-embolized liver. It is important to predict hypertrophy of un-embolized liver following PVE to decide a subsequent tactics in patients with liver tumors. The hypertrophy following PVE was evaluated in reference to embolized liver volume and a preceding use of transcatheter hepatic arterial chemoembolization (HACE) in this study.

METHODS

Thirty patients with liver tumors were studied. PVE was performed transhepatically. Ethanol (15-65 ml) was injected into portal veins, which perfused the liver segment bearing the tumor until occlusion. Embolization was performed at subsegmental portal branches in five patients, segmental branches in 11 patients and right portal veins in 14 patients. Twenty-three patients with underlying chronic liver disease and hepatocellular carcinoma (HCC) underwent PVE 2-6 weeks after HACE. The remaining seven patients without underlying chronic liver disease had bile duct cancer (6) or liver metastasis (1), and underwent PVE alone. Segmental volume in the liver was measured with computed tomography before and 4 weeks after PVE.

RESULTS

The degree of hypertrophy showed a significant correlation with embolized liver volume (r=0.685, p<0.001). Increase in un-embolized liver volume was 2.4+/-5.8% with subsegmental embolization (NS), 15.2+/-6.4% with segmental embolization (p<0.01) and 46.5+/-18.8% with right PVE (p<0.001). In 14 patients with right PVE, degree of hypertrophy in seven patients with HACE was greater than that in seven patients without HACE (56.7+/-21.6% vs 36.4+/-7.4%; p<0.03).

CONCLUSIONS

Hypertrophy of the un-embolized liver parenchyma following PVE was correlated with embolized liver volume and was augmented with combined use of HACE.

Spiral computed tomography for staghorn calculi

OBJECTIVES

To assess the utility of spiral computed tomography (CT) with three-dimensional reconstruction for preoperative planning of percutaneous nephrostolithotomy in patients with complex branched calculi (full staghorns).

METHODS

Patients with complex branched stones were imaged with spiral CT with three-dimensional reconstruction. These images were compared with standard imaging modalities, including excretory urography and plain radiographs, for planning percutaneous access for nephrostolithotomy. The utility of the scan was evaluated.

RESULTS

Ten patients with branched calculi were studied. Anatomic abnormalities were present in 5 patients. Excellent three-dimensional images were obtained in all patients without any complications related to the study. In 1 patient with multiple calculi in a horseshoe kidney, the three-dimensional image indicated a branched stone. The spiral CT scan was not helpful in directing percutaneous access in any patient. In a single patient, residual fragments noted during nephrostolithotomy were located by reference to the spiral CT scan.

CONCLUSIONS

Spiral CT scans with three-dimensional reconstruction provide three-dimensional imaging of branched renal calculi. This modality provides minimal additional information over that obtained from standard radiographic studies for guiding nephrostolithotomy and cannot be recommended as a routine preoperative study. It was helpful in 1 patient to locate a residual fragment.

Diagnostic workup of patients with suspected pancreatic carcinoma: the University of California-Los Angeles approach

BACKGROUND

A large number of diagnostic procedures (e.g., ultrasound, computed tomography [CT] scan, fine-needle aspiration [FNA], angiography, endoscopic retrograde cholangiopancreatography [ERCP], and laparoscopy), are available to the clinician as he/she pursues the workup of patients who are thought to have a pancreatic (periampullary) malignancy. Not all of these procedures should be used in every patient and some have been overused.

METHODS

Based on a current literature review and their own experience, the authors describe the rationale of the diagnostic workup in patients with suspected pancreatic carcinoma in a single institution (a university medical center).

RESULTS

Helical CT scan provides the best overall assessment of patients with periampullary malignancies, and it is often the only test required. If the patient's history and blood test abnormalities suggest pancreatic carcinoma and the helical CT scan shows a mass in the head of the pancreas that appears to be resectable, the patient should be prepared for surgery. If no mass is apparent on the helical CT scan, a diagnostic ERCP is indicated. If microscopic proof of the diagnosis will avoid surgery, then an FNA for cytology should be performed. When unresectability appears likely and cannot be confirmed in less invasive ways, laparoscopy is indicated.

CONCLUSIONS

In patients with periampullary malignancies, helical CT scan provides the best overall assessment. Guidelines are presented for the selective use of ultrasound, FNA, ERCP, and laparoscopy, which are important for the most cost-effective workup of these patients.

Helical CT for detection and characterization of renal masses

Helical CT permits the radiologist to image the kidney continuously, eliminating the chances of scanner misregistration. In addition, the kidneys can now be imaged during essentially any phase of contrast material enhancement. Although this offers greater flexibility to the imager, a number of potential problems with helical CT must be considered, particularly when it is performed during the cortical phase of renal enhancement. This article reviews both the advantages and potential pitfalls of helical CT when used for both detection and characterization of renal masses.

Three-dimensional reconstruction of an iliac artery aneurysm in a man with obstructive uropathy

Reconstruction of three-dimensional images is performed either by scanner-based systems or by independent computers. The advantages of a stand-alone system include compatibility with multiple imaging modalities, more advanced technology, and increased user interaction. This report illustrates the use of a stand-alone system for the less commonly utilized purpose of three-dimensional reconstruction of abdominal soft tissues. It further demonstrates the merit of three-dimensional imaging as an important diagnostic adjunct and as a valuable source of preoperative surgical information.

Biliary tract obstruction. The role of spiral CT in detection and definition of disease

The purpose of this study was to assess the efficacy of spiral computed tomography (CT) in determining the etiology of biliary tract obstruction. Spiral CT studies performed over a 9-month period in 42 consecutive patients with suspected biliary tract obstruction were reviewed. Analysis of scans included localizing the obstruction and then defining a specific etiology. Pertinent associated findings such as porta hepatis or peripancreatic adenopathy, hepatic or peritoneal metastases, and pancreatic pseudocyst or abscess formation were also assessed. Spiral CT demonstrated the level of obstruction in all 30 patients in whom there was biliary tract dilatation. Thirty-two diagnoses were rendered in 30 patients, with specific obstructing lesions identified in 28 instances (88%). Twenty-five (78%) of 32 specific pathological diagnoses were correct. The positive predictive value for neoplasms in the pancreatic head was 100% (n = 17). Two patients with characteristic CT changes of sclerosing cholangitis were diagnosed as having superimposed cholangiocarcinoma, although the results of biopsies for neoplasm were negative. The sensitivity of spiral CT for detection of common duct calculi was 67% (n = 3). Due to optimal contrast enhancement of both hepatic and pancreatic parenchyma, spiral CT enables excellent visualization of the biliary system and provides a specific explanation for biliary tract obstruction in nearly all cases. Spiral CT can usually distinguish neoplastic from nonneoplastic causes of jaundice. When distal common duct obstruction is detected in the absence of an identifiable mass or focal ductal wall thickening, neoplasia is unlikely. It is difficult to exclude sclerosing cholangitis from cholangiocarcinoma on the basis of spiral CT findings, and in these patients, biopsy or close follow-up is recommended to exclude the possibility of a biliary neoplasm.

Helical CT of the larynx: a comparative study with conventional CT scan

AIM

To compare helical and conventional CT scans of the larynx.

PATIENTS AND METHODS

Thirty-three patients underwent helical and conventional CT studies of the neck and the larynx using 3 mm section collimation for both studies and a table feed of 4 mm/sec for helical CT. Helical scans were reconstructed at 2 mm increments. Two independent observers rated the visibility of the laryngeal structures from 1 (poor and non diagnostic) to 5 (excellent and diagnostic), and motion artifacts from 1 (> or = 10 degraded scans) to 5 (no motion artifacts).

RESULTS

The motion artifacts score was significantly better for helical CT. No significant difference was observed for the laryngeal structures score between helical and conventional CT studies. The interobserver kappa mean value was 0.756 and 0.68 for helical and conventional CT, respectively.

CONCLUSION

Helical CT can be routinely performed and replace conventional CT study for the evaluation of laryngeal diseases.

Abdominal computed tomography scan as a screening tool in blunt trauma

BACKGROUND

One of the most difficult problems in blunt trauma is evaluation for potential intraabdominal injury. Admission for serial abdominal exams remains the standard of care after intraabdominal injury has been initially excluded. We hypothesized a normal abdominal computed tomography (CT) scan in a subgroup of minimally injured patients would obviate admission for serial abdominal examinations, allowing safe discharge from the emergency department (ED).

METHODS

We reviewed our blunt trauma experience with patients admitted solely for serial abdominal examinations after a normal CT. Patients were identified from the trauma registry at a Level 1 trauma center from July 1991 through June 1995. Patients with abnormal CTs, extra-abdominal injuries necessitating admission, hemodynamic abnormalities, a Glasgow Coma Scale less than 13, or injury severity scores (ISSs) greater than 15 were excluded. Records of 238 patients remained; we reviewed them to determine the presence of missed abdominal injury.

RESULTS

None of the 238 patients had a missed abdominal injury. Average ISS of these patients was 3.2 (range, 0 to 10). Discharging these patients from the ED would result in a yearly cost savings of $32,874 to our medical system.

CONCLUSIONS

Abdominal CT scan is a safe and cost-effective screening tool in patients with blunt trauma. A normal CT scan in minimally injured patients allows safe discharge from the ED.

Case report. Congenital left ventricular aneurysm diagnosed by spiral CT angiography

We report a rare case of congenital left ventricular aneurysm, diagnosed by spiral CT angiography. Despite 1 s time acquisition, spiral CT, with adequate acquisition parameters and bolus injection of contrast medium, produced sufficiently good images to permit visualization of the aneurysm. Subsequently, reconstructions (shaded surface display and multiplanar reformation) were performed to demonstrate the relationship of the aneurysm with the remainder of the left ventricle, the wide neck of the aneurysm, and the absence of contractility, therein permitting differentiation from a congenital diverticulum.

[Spiral scanners: principles and clinical prospects]

Helical computed tomography (CT) involves continuous patient shifting during X-ray source rotation and data acquisition. As a result, a volume data set is obtained in a short period of time. An entire examination can be completed in a single breath hold, without additional radiation exposure, optimizing enhancement with intravenous contrast material. By overcoming some of the constraints of conventional CT, helical CT has advanced prospects, including multiplanar reconstruction and CT angiography, as reviewed in this article. There are undergoing studies to confirm these preliminary findings: its clinical applications are currently evolving.

CT evaluation of treatment response in advanced gastric cancer

Ninety-one patients with advanced gastric carcinoma were followed by serial computed tomography (CT) in a phase II study using multi-agent chemotherapy. Regression of primary tumour was seen in 43, with complete resolution in 5 and > 50% regression in 29. Involvement of loco-regional lymph nodes was seen in 43 patients, with complete resolution in 16, and > 50% regression in 21. Hepatic metastases were seen in 40 patients, with complete resolution in three and > 50% regression in 17. Regression in other less common sites in the chest and abdomen were also documented. The pattern of maximum response in all sites of disease was seen within the first 12 weeks of chemotherapy. The difficulties of disease management are discussed and recommendations for CT evaluation in this group of patients are made.

Detection of hypervascular hepatocellular carcinoma by using spiral volumetric CT: comparison of US and MR imaging

BACKGROUND

Most hepatocellular carcinomas (HCCs) are hypervascular and arise in the liver with chronicity. Spiral volumetric CT (SVCT) is a new rapid-scan technique that offers whole-liver scanning during the arterial-dominant phase. The main aim of the present study is to evaluate the detectability of hypervascular HCC with SVCT as compared with ultrasonography (US) and magnetic resonance (MR) imaging.

METHODS

Forty-three hypervascular HCCs in 512 patients with chronic liver disease were examined with US, precontrast SVCT, postcontrast SVCT during the arterial-dominant phase (CT-ADP) and during the equivalent-phase (CT-EP) noncontrast MR imaging and angiography including SVCT during arteriography and arterial portography. Angiographic and follow-up findings were used as the gold standard if the lesion was not confirmed histologically.

RESULTS

The sensitivity was 61% with precontrast CT, 84% with CT-ADP, 58% with CT-EP, 70% with US, 72% with MR, and 95% with the combination of these five modalities. Five HCCs (12%) were detected with only CT-ADP. The vascularity of HCC was correctly evaluated as hypervascular in 38 nodules (88%) with the combination of precontrast CT and CT-ADP.

CONCLUSIONS

We suggest that the combination of precontrast SVCT and CT-ADP is an essential modality to screen for HCC in patients with chronic liver disease. CT-EP did not contribute to the detection of hypervascular HCC.

Hepatocellular carcinoma: findings on spiral CT during arterial portography

BACKGROUND

To determine characteristic imaging features of hepatocellular carcinoma (HCC) on spiral CT during arterial portography (SCTAP) and to correlate the presence or absence of spontaneous portosystemic shunts with the degree of hepatic parenchymal enhancement during SCTAP in patients with HCC.

METHODS

SCTAP scans of 20 patients with HCC were retrospectively analyzed for tumor features, degree of hepatic parenchymal enhancement, and presence or absence of spontaneous portosystemic shunts.

RESULTS

Nineteen tumors (95%) were hypoattenuating masses and one (5%) was isoattenuating compared with the liver on SCTAP. In seven patients (35%), the tumor was homogeneous in attenuation. Tumor margins were smooth and regular in 12 patients (60%). Vascular invasion and encapsulation were depicted in 10 patients (50%). A high degree of hepatic parenchymal enhancement was observed in 14 patients; one of them (7%) had spontaneous portosystemic shunts. Poor or moderate enhancement was observed in six patients; five of them (83%) had spontaneous portosystemic shunts (p < .001).

CONCLUSION

The presence of a low attenuated homogeneous intrahepatic mass with associated vascular invasion on SCTAP scans should raise the possibility of HCC. The presence of spontaneous portosystemic shunts is associated with poor or moderate parenchymal enhancement.

Efficacy of unanesthetized spiral computed tomography scanning in initial evaluation of childhood leukocoria

PURPOSE

To evaluate the use of spiral/helical computed tomography (CT) in the preoperative evaluation of pediatric leukocoria.

METHODS

A total of 34 patient charts and imaging studies were reviewed from a consecutive series of children referred with the diagnosis of presumed retinoblastoma. Of these patients, 31 had a confirmed diagnosis of retinoblastoma. Three patients had simulating lesions, including one patient with persistent hyperplastic primary vitreous and two with Coats disease.

RESULTS

In all patients, a diagnosis of intraocular retinoblastoma could be established or excluded at the same clinical level by spiral CT as by conventional CT. Spiral CT of the eye, orbit, and midline structures was performed without a requirement for patient anesthesia. This technique resulted in a reduced volume of contrast material required for evaluation of the central nervous system and a small decrease in total radiation exposure. There was an attendant reduction in the amount of monitoring equipment required and the necessity for attending anesthesia staff.

CONCLUSIONS

The primary advantage of spiral CT is reduced anesthesia risk in small children. In addition, this technique provides necessary clinical information with a reduction in image acquisition time, monitoring equipment, and monitoring staff.

Pseudothrombosis of the right ovarian vein. Pitfall of abdominal spiral CT

We present the computed tomography (CT) findings of pseudothrombosis of the right ovarian vein. In two young multiparous women, pseudothrombosis was detected on early-phase spiral CT scans by the presence of retrograde flow of contrast medium down the left ovarian veins. Asymmetry of density seen in the ovarian veins in the early phase of spiral CT scanning related to reflux in the left ovarian vein should not be mistaken for right ovarian vein thrombosis.

Planning of liver surgery using three dimensional imaging techniques

In the simplified Couinaud classification, in which the liver is divided into eight segments, each supplied by a central vasculo-biliary sheath, little attention is given to the high prevalence of anatomical variations which occur, especially in the right hemiliver. Using volumetric acquisition techniques, such as magnetic resonance imaging or spiral computed tomography scanning, detailed insight into the individual segmental anatomy can now be obtained in a non-invasive manner. The significance of this anatomical insight lies in the planning of anatomical resections, whereby the relationship between tumour and individual segmental anatomy can be depicted in a three-dimensional format. As such, three dimensional (3D) liver imaging helps to design an individualised resection, tailored to the topographical relationship between individual segmental anatomy and tumour tissue present. Three dimensional liver imaging is of most practical value if a resection of one or more segments or sectors is considered, especially in the right hemiliver. In these cases, 3D liver imaging can demonstrate the precise location of the scissuras to the surgeon pre-operatively.

Hepatic vascular diseases: CT and MRI

Continued development of CT and MRI techniques has allowed these modalities to detect most hepatic vascular diseases, often obviating more invasive tests. In this article, the techniques for hepatic vascular diagnosis are reviewed, with emphasis on spiral CT and two-dimensional MRI techniques, and then the major vascular diseases on which these two modalities have a significant diagnosing impact are considered.

Intrahepatic cholangiocarcinoma: findings on spiral CT during arterial portography

To attempt to determine the characteristic imaging features of intrahepatic cholangiocarcinoma on spiral CT during arterial portography (CTAP), spiral CTAP examinations of 17 patients with pathologically confirmed intrahepatic cholangiocarcinoma were reviewed in consensus by three radiologists. The diameter of the tumors ranged from 1 to 12 cm (mean diameter, 6.6 cm). All tumors (100%) were hypoattenuating masses on spiral CTAP. In 11 cases, the tumor was homogeneous in attenuation (65%). Tumor margins were smooth and regular in 11 cases (65%). Vascular invasion was found in 14 cases (82%). Intrahepatic bile duct dilatation was present in seven cases (41%). This review shows that intrahepatic cholangiocarcinoma is associated with a constellation of findings on spiral CTAP. The presence of a low attenuation homogeneous intrahepatic mass with vascular invasion and intrahepatic bile duct dilatation on spiral CTAP images should raise the possibility of intrahepatic cholangiocarcinoma. However, these findings can be associated with other types of primary and secondary malignant hepatic tumors.

Perfluoroctyl bromide as a blood pool contrast agent for computed tomographic angiography

RATIONALE AND OBJECTIVES

We determined whether perfluoroctyl bromide (perflubron) could be used as a computed tomography (CT) angiographic agent by studying vessel visibility (celiac artery, superior mesenteric artery [SMA], and renal arteries) with spiral CT and three-dimensional (3D) reconstructions.

METHODS

Five rhesus monkeys were examined with a perflubron emulsion (90% [w/v] perfluorochemical; administered intravenously at a dose of 1.5 ml/kg and at a rate of 0.5 ml/sec. Spiral CT was performed immediately and at 5 hr after injection. Three dimensional images of the aorta at the level of the celiac artery, SMA, and renal arteries were reconstructed and blindly rated 0-4 (0 = not seen; 4 = excellent visualization) by two observers.

RESULTS

All the vessels had the best ratings immediately after injection: celiac artery, 2.8 +/- 0.42; SMA, 2.7 +/- 0.48; left renal artery, 2.1 +/- 0.99; and right renal artery, 1.2 +/- 1.03. The ratings after the 5-hr delay were as follows: celiac artery, 1.3 +/- 1.34; SMA, 1.5 +/- 1.08; left renal artery, 1.5 +/- 0.97; and right renal artery, 1.2 +/- 0.79.

CONCLUSIONS

Spiral CT angiography with a perflubron emulsion successfully demonstrated all vessels immediately and at 5 hr after contrast agent infusion. Further refinements of the dose, rate, and reconstruction technique are expected to increase vessel visibility over this wide imaging window.

Preoperative assessment of abdominal aortic aneurysm: the value of helical and three-dimensional computed tomography

PURPOSE

The purpose of this study was to evaluate the utility of helical computed tomography (CT) in the preoperative assessment of abdominal aortic aneurysms (AAA) and to compare its accuracy with aortography and operative findings.

METHODS

Thirty-two patients with suspected AAA were evaluated by helical CT with either 5 mm collimation (slice thickness) or a combination of 3 mm collimation through the renal and mesenteric arteries and 7 mm collimation through the remainder of the AAA. Three-dimensional reconstructions were performed with use of three different techniques, and results were compared with aortography and surgery.

RESULTS

Twenty-five patients were found to have an aneurysm, and 19 subsequently underwent surgery. Standard angiography was also performed in 13. The location, size, and extent of the aneurysm, as well as the wall calcification and intraaneurysmal thrombus, were well depicted with helical CT. The visceral aortic branches, including the detection of renal artery stenosis and accessory renal arteries, were consistently seen with the 3 mm/7 mm collimation protocol and three-dimensional reconstruction.

CONCLUSION

Helical CT with three-dimensional display of the aorta and its branches combines the advantages of conventional CT imaging and aortography. This technique appears to provide comprehensive preoperative evaluation of AAA.

Morphology of small aneurysms: definition and impact on risk of rupture

BACKGROUND

Parietal characteristics of small aortic aneurysms predictive of increased risk of rupture are unknown.

METHODS

Prospective morphologic evaluation was performed in 135 consecutive cases of small (< 5 cm) abdominal aortic aneurysm. Twelve cases (9%) were found to be ruptured and sent for emergency surgery. The remaining 123 patients were evaluated with ultrasonography, angiography, and intraoperatively during elective surgery. Ninety-six (78%) also underwent computerized tomography (CT) scanning. The evaluation assessed the thickness of the endoluminal thrombus and arterial wall as well as the presence of saccular outpouchings ("blisters"). Also noted were any areas of impending rupture, defined as discontinuity of the arterial wall with only a thrombus preventing rupture.

RESULTS

Blisters were discovered intraoperatively in 12 aneurysms. Digital subtraction angiography (DSA) revealed 3 (25%) of these preoperatively. Eleven of the patients with blisters were examined preoperatively with CT scanning, which detected 3 blisters (27%). Both endoluminal thrombus and wall thickness were measurable by CT scan but not ultrasonography. The incidence of impending rupture was significantly greater in patients with blisters than in those without (71% versus 29%, P = 0.0001). The incidence of impending rupture was similar whether the amount of endoluminal thrombus was more or less than 2 cm (57% versus 40%, P = 0.386). Rupture was no more frequent when aneurysmal walls were thicker or thinner than 0.3 cm (14% versus 20%, P = 0.719). In an analysis using logistic regression, the presence of a blister was the only independent morphologic predictor of impending rupture (P = 0.001, Wald = 15).

CONCLUSION

In patients with small aneurysms, increased attention should be directed to the preoperative detection of blisters.

Spiral CT of the pancreas

Spiral CT technology now represents the gold standard in the evaluation of known or suspected pancreatic pathology. For both neoplastic and inflammatory diseases of the pancreas, spiral CT offers many unique advantages over conventional dynamic CT scanning. This article reviews the basic technique and applications of spiral CT in evaluation of the pancreas, with emphasis on its specific advantages.

Spiral CT of the liver: current applications

Spiral CT allows rapid imaging of the liver resulting in improved contrast dynamics compared with conventional CT techniques. Improved lesion detection has been shown with spiral CT by using overlapping reconstruction intervals and by eliminating respiratory misregistration. Vascular and parenchymal abnormalities, including portal venous thrombosis or cirrhosis with development of collateral vessels, are readily appreciated using spiral technique. Combining spiral CT and portography enhances lesion detection by maintaining high levels of hepatic contrast enhancement for the duration of the liver scan.