Helical CT of renal masses: the value of delayed scans

OBJECTIVE

Routine scanning techniques used for helical CT of the abdomen result in dense cortical opacification of the kidney, whereas the medulla and collecting system are not well opacified, which potentially compromises detection of renal masses. The purpose of this retrospective study was to determine if additional delayed views (taken approximately 2-4 min after the start of injection of contrast material) are necessary for the detection and characterization of renal masses.

MATERIALS AND METHODS

Early (60-70 sec after the start of the injection of contrast material) and delayed scans of 40 patients with suspected renal masses were blindly evaluated by two observers. The patients harbored a total of 187 renal masses (including 62 solid masses). Each region of the kidney (upper, middle, and lower pole) was scored for the presence of a mass. Scoring was done as a binary decision and also as a five-point confidence score for receiver operating characteristic analysis.

RESULTS

We found 97 regions that contained renal masses and 114 regions that did not. Receiver operating characteristic analysis revealed the observers to have significantly greater confidence in detection of renal masses on the delayed scans. The binary data showed the two observers to have a sensitivity of 97% for delayed scans versus 77% (p = .0002) and 89% (p = .027), respectively, for the early scans. For the first observer, early and delayed scans were of equal specificity, but for the second observer, the delayed scans yielded greater specificity (94% versus 85%, p = .024). On the early scans, both observers were significantly more likely to miss a neoplastic lesion than a nonneoplastic lesion. The less experienced of the two observers also tended to have greater difficulty in characterizing the lesions on the early scans.

CONCLUSION

Because of the significant risk of missing a renal mass, especially a neoplasm, on early cortical-phase scans, additional delayed scans appear justified when a renal mass is suspected on the basis of other imaging tests or clinical history.

Delayed enhanced CT for differentiation of benign from malignant adrenal masses

PURPOSE

To determine whether adenomas can be differentiated from nonadenomas on 1-hour-delayed enhanced computed tomographic (CT) scans.

MATERIALS AND METHODS

In a prospective evaluation of 51 adrenal masses in 39 patients, the CT attenuation was measured at the time of contrast enhancement and 1 hour later. The results were compared for adenomas (n = 41) and metastases (n = 10).

RESULTS

On 1-hour-delayed enhanced CT scans, the mean attenuation of the adenomas was 11 HU +/- 13 versus 49 HU +/- 8.3 for metastases (P < .001). At a threshold value of 30 HU, specificity and positive predictive value for the diagnosis of adenoma were 100% with a sensitivity of 95%. The mean decrease in attenuation during the 1-hour delay was 74% +/- 37 for the adenomas versus 31% +/- 28 for the metastases (P < .001).

CONCLUSION

CT densitometry on delayed scans obtained 1 hour after contrast enhancement may be useful in characterizing an adrenal mass as an adenoma. When CT is performed with a 150-mL bolus injection of contrast material and with the scanning parameters described in this study, other procedures or imaging studies may be unnecessary if the mass measures less than 30 HU on the delayed scans.

Segmental anatomy of the liver under the right diaphragmatic dome: evaluation with axial CT

PURPOSE

To evaluate the segmental anatomy of the liver under the right side of the diaphragm with axial computed tomography (CT).

MATERIALS AND METHODS

Forty-six patients underwent CT arteriography with selective catheterization of the right hepatic artery in 25 cases, the left hepatic artery in 12, the anterior branch of the right hepatic artery in six, the posterior branch of the right hepatic artery in five, the superior anterior branch of the right hepatic artery in 10, and the superior posterior branch of the right hepatic artery in eight.

RESULTS

The boundary between the right and left lobes shifted by 16.2 degrees +/- 16.8 anteriorly, and the boundary between the anterior and posterior segments shifted by 43.9 degrees +/- 14.0 posteriorly to the line through the middle or right hepatic vein from the inferior vena cava. The top of the liver consisted of both lobes in 22 patients, only the right lobe in 17, and only the left lobe in two. Participation of segment 7 in the top was not demonstrated.

CONCLUSION

The line that extends beyond the middle or right hepatic vein from the inferior vena cava does not coincide with the main or right longitudinal scissura on axial images of the upper portion of the liver.

Pediatric great vessel anomalies: initial clinical experience with spiral CT angiography

PURPOSE

To evaluate the use of spiral computed tomographic (CT) angiography for the diagnosis of pediatric great vessel anomalies.

MATERIALS AND METHODS

Techniques used in adult CT angiography were modified to allow imaging of 15 children aged 1 month to 12 years. Two-dimensional axial images and three-dimensional shaded surface display images of the airway and great vessels were generated from volumetric CT data and evaluated prospectively. Findings were correlated with results obtained at surgery (five patients), autopsy (one patient), bronchoscopy (one patient), or other imaging studies (eight patients).

RESULTS

In 14 patients, CT angiography accurately demonstrated vessel anomalies, including double or right aortic arch (seven cases), aberrant subclavian artery (six cases), innominate artery compression syndrome (one case), unilateral pulmonary artery agenesis (one case), and pulmonary artery enlargement (three cases). One patient had normal vasculature.

CONCLUSION

CT angiography is feasible in children and can be used to delineate abnormal great vessel anatomy.

Diagnosis of Hirschsprung's disease

OBJECTIVE

Our aims were to determine the validity of using low-osmolality water-soluble contrast enemas (WSCE) in neonates and infants with suspected Hirschsprung's disease (HD) and to devise a scoring system that uses a checklist of radiologic signs to determine the probability of HD.

MATERIALS AND METHODS

The records of all patients referred by pediatric surgeons from 1988 through 1992 for the radiologic investigation of possible HD were retrospectively reviewed. Thirty-eight patients who were from 2 days to 9 months old were studied; 20 of them were neonates (less than 1 month old). Of all the patients, 24 underwent WSCE and the other 14 underwent barium enema. For all patients, HD had been diagnosed by rectal biopsy or excluded by biopsy, clinical follow-up, or both. Radiographs were read by a gastrointestinal radiologist who used a checklist of diagnostic criteria reported in the literature. The sensitivity had specificity of the findings were compared with those in the literature.

RESULTS

Of the 18 patients with HD, 12 were neonates. All reported radiologic diagnostic criteria were seen; the frequency, sensitivity, and specificity of the findings were reported. Twenty percent (n = 2) of HD patients in the WSCE group (n = 10) had negative findings. Two of the 12 neonates developed colonic perforation, one during the enema and the other within 24 hr of the procedure.

CONCLUSION

WSCE has a sensitivity and specificity equivalent to those of the barium enema for the detection of HD. For the two patients with perforation, the use of WSCE was of considerable benefit, avoiding the problems associated with barium spillage into the peritoneal cavity. A scoring system for diagnostic enemas is feasible.

Traumatic aortic injury: diagnosis with contrast-enhanced thoracic CT--five-year experience at a major trauma center

PURPOSE

To review the literature and the authors' experience with admission contrast material-enhanced computed tomography (CT) in patients admitted after blunt trauma.

MATERIALS AND METHODS

From January 1990 to December 1994, thoracic CT was performed to evaluate traumatic aortic injury in 677 patients with positive or equivocal findings at chest radiography. CT scans positive for mediastinal hemorrhage or aortic injury were retrospectively reviewed and interpreted by consensus, with angiographic and surgical confirmation.

RESULTS

CT findings were negative for TAI in 570 (84%) of the 677 patients. Mediastinal hemorrhage was reported in 100 patients and was the only abnormality in 79 of them. Findings at angiography were negative for traumatic aortic injury in 77 (97%). CT signs of traumatic aortic injury in 21 patients included contour abnormality or pseudoaneurysm (n = 19), intimal flap(s) (n = 8), and pseudocoarctation (n = 3). Findings at angiography were positive for traumatic aortic injury in 19 (90%). For aortic injury and mediastinal hemorrhage, respectively, specificity for traumatic aortic injury was 99% and 87% and sensitivity was 90% and 100%; at meta-analysis of data from the authors and the literature, sensitivity was 97.0% and 99.3% and specificity was 99.8% and 87.1%. Reliance on findings at admission CT rather than radiography to indicate suspicion for traumatic aortic injury before angiography resulted in savings of more than $365,000.

CONCLUSION

The CT finding of mediastinal hemorrhage alone is sensitive for traumatic aortic injury, but the finding of aortic injury is more specific.

Focal liver disease: comparison of breath-hold T1-weighted MP-GRE MR imaging and contrast-enhanced CT--lesion detection, localization, and characterization

PURPOSE

To compare breath-hold T1-weighted magnetization-prepared gradient-echo (MP-GRE) magnetic resonance (MR) imaging with contrast material-enhanced computed tomography (CT) in the assessment of focal liver disease.

MATERIALS AND METHODS

The MR and CT images obtained in 64 patients with focal liver disease were reviewed by six independent reviewers in a randomized, blinded fashion. Sets of axial T1-weighted MP-GRE images, three-plane (a compilation of axial, sagittal, and coronal) T1-weighted MP-GRE images, and contrast-enhanced CT scans were analyzed. T2-weighted spin-echo (SE) MR images were also compared with CT scans.

RESULTS

Lesions were detected, localized, and characterized more accurately and generally with greater confidence with three-plane T1-weighted MP-GRE imaging than with CT (P < .01). Axial T1-weighted MP-GRE imaging was also superior (P < .05) to CT (although slightly less superior than three-plane imaging) except in the characterization of specific lesions, where both techniques were equal. T2-weighted SE MR imaging and CT were about equal.

CONCLUSION

Lesion detection, localization, and characterization are performed more accurately and confidently with breath-hold T1-weighted MP-GRE imaging than with contrast-enhanced CT, particularly when breath-hold images are obtained in three planes.

Feasibility, safety and clinical utility of angiography in patients with suspected pulmonary embolism

The purpose of our study was to assess feasibility, safety and clinical utility of selective pulmonary angiography in patients with suspected pulmonary embolism and a nondiagnostic lung scan. The design was a prospective, descriptive study. The subjects were consecutive patients with clinically suspected pulmonary embolism and a nondiagnostic lung scintigram in whom pulmonary angiography was considered. Angiography was withheld in cases of manifest heart failure, renal failure, mean pulmonary artery pressure above 40 mmHg, or if there were compelling clinical reasons. All patients were followed-up for 6 months. The outcome measures were successful angiography, morbidity, mortality and recurrent pulmonary embolism in patients with normal angiogram in whom anticoagulants were withheld during 6 months of follow-up. Of 487 patients, 196 (40%) had nondiagnostic lung scan findings. In 46 patients (23%) pulmonary angiography was withheld. Pulmonary embolism was excluded in 105 patients (70%), and proven in 40 (27%) patients. In 5 (3%) patients the angiogram was inadequate for interpretation. No fatal complications were encountered [95% confidence interval (CI) 0-2.4%]. Nonfatal complications occurred in 3 patients (2%; 95% CI 0.4-6.0%); all recovered spontaneously. None of 105 patients with a normal angiogram returned with thromboembolism during follow-up (0%; 95% CI 0-3.4%). Pulmonary angiography is safe, rules out pulmonary embolism in two thirds of patients with a nondiagnostic lung scan and can be performed in almost 80% of these patients. It is safe to withhold long-term anticoagulants if a normal angiogram is obtained in this subgroup of patients with clinically suspected pulmonary embolism.

Deep venous thrombosis of the lower extremity: efficacy of spiral CT venography compared with conventional venography in diagnosis

PURPOSE

To compare the efficacy of spiral computed tomographic (CT) venography with conventional venography in the diagnosis of suspected deep venous thrombosis (DVT).

MATERIALS AND METHODS

In a prospective study, 52 consecutive patients with clinically suspected unilateral or bilateral DVT were studied with CT venography and conventional venography. In cases in which conventional venographic findings were inconclusive, color-coded duplex sonography and follow-up examinations were performed to make a final diagnosis. CT venography of both extremities covered a 100-cm section from the ankle to the inferior vena cava (IVC). Contrast material diluted with saline was injected in a dorsal vein of each foot. CT and conventional venography (including color-coded duplex sonography and follow-up findings) were correlated for three venous regions for each patient.

RESULTS

Correlation was excellent between CT and conventional venographic findings in the detection of DVT. The sensitivity of CT venography was 100% (confidence interval: 0.92, 1.00), specificity was 96% (confidence interval: 0.84, 0.98), positive predictive value was 91%, and negative predictive value was 100%. CT venography more clearly demonstrated thrombus extension of DVT into the pelvic veins and IVC than conventional venography alone.

CONCLUSION

CT venography is a valuable tool in the diagnosis of DVT. Compared with conventional venography, CT requires use of 80% less contrast material.

Iohexol clearance for renal function measurement in gynaecologic cancer patients

PURPOSE

To determine a valid and practical routine for glomerular filtration rate measurement in gynaecologic cancer patients.

MATERIAL AND METHODS

The established method, endogenous creatinine clearance, was compared to 51Cr-EDTA clearance and contrast medium clearance in 68 women with various gynaecologic carcinomas. Contrast medium clearance was determined in association with conventional urography (iohexal 300 mg I/ml, 40 ml) for evaluation of urinary tract involvement by the tumour. Automated X-ray fluorescence analysis equipment was used for the plasma analysis of iohexol and clearance calculations. Endogenous creatinine clearance and 51Cr-EDTA clearance were determined according to standard routine procedures. Simultaneous determinations of contrast medium clearance and 51Cr-EDTA clearance (n = 33), contrast medium clearance and endogenous creatinine clearance (n = 50), as well as 51Cr-EDTA clearance and endogenous creatinine clearance (n = 30) were compared.

RESULTS AND CONCLUSION

The mean differences were -2.8 (SD 6.6), -1.8 (SD 22.3), and 2.7 (SD 18.3) ml/min/1.73 m2, respectively. It is concluded that contrast medium clearance is as adequate as 51Cr-EDTA clearance for glomerular filtration rate measurement. We suggest that contrast medium clearance should replace endogenous creatinine clearance, especially in patients referred for urography.

Two-phase helical CT for pancreatic tumors: pancreatic versus hepatic phase enhancement of tumor, pancreas, and vascular structures

PURPOSE

To quantitatively evaluate and validate a two-phase helical computed tomographic (CT) protocol for evaluation of pancreatic tumors.

MATERIALS AND METHODS

Twenty-seven patients with pathologically proved pancreatic adenocarcinomas prospectively underwent two-phase CT examination with helical acquisition during the pancreatic phase (40-70 seconds after infusion of intravenous contrast material at 3 mL/sec) and the hepatic phase (70-100 seconds after infusion). Mean CT attenuation values of tumor, bordering pancreas, and all major peripancreatic vessels were obtained for both time intervals.

RESULTS

Mean tumor-pancreas contrast was significantly greater during the pancreatic phase (67 HU +/- 19) than the hepatic phase (39 HU +/- 16) (P < .001) This was the result of both greater enhancement of normal pancreas and lower tumor enhancement during the pancreatic phase. Opacification of all vascular structures, including the portal vein, was also greater during the pancreatic phase (P < .001).

CONCLUSION

Two-phase helical CT with pancreatic phase acquisition provides statistically significantly better pancreatic, arterial, and portal venous enhancement than that of hepatic phase imaging, with improved tumor-pancreas contrast.

Coronary arteriography with an oxygenated contrast medium: cardiac effects in dogs with and without acute ischemic heart failure

RATIONALE AND OBJECTIVES

We investigated the possible cardiac effects of oxygen addition to contrast media (CM) during coronary arteriography in dogs that did and did not have ischemic heart failure.

METHODS

Acute ischemic heart failure was induced by injecting small plastic microspheres into the left coronary artery of 18 dogs. Hemodynamic and electrophysiologic measurements were performed during a single injection before and during heart failure and during a single injection and five rapidly repeated CM injections during heart failure. Iohexol supplemented with electrolytes (iohexol + electrolytes = IPE), oxygenated IPE (IPE+O), Ringer acetate, and oxygenated Ringer acetate were injected into the left coronary artery.

RESULTS

Single injections of IPE and IPE+O induced small hemodynamic and electrophysiologic effects. However, repeated injections of IPE and IPE+O increased left ventricular inotropy (maximum value of the first derivative of the left ventricular pressure) by 36% and 39%, reduced heart rate by 7% (for both), and lengthened QTc time (corrected QT interval) by 39 and 38 msec, respectively. A comparison of IPE and IPE+O revealed no statistically significant differences.

CONCLUSION

Although electrolyte addition to nonionic CM may reduce the risk of cardiac complications during coronary arteriography, oxygenation does not seem to significantly further reduce this risk.

Follow-up after insertion of Bird's Nest inferior vena caval filters

OBJECTIVE

To determine the long-term clinical and radiographic outcome of patients who undergo insertion of a Gianturco-Roehm Bird's Nest vena caval filter (Cook Inc., Bloomington, Ind.).

PATIENTS AND METHOD

The medical records of 40 patients who, over a 34-month period, underwent insertion of a Bird's Nest filter were reviewed and the reasons for filter insertion determined. The causes of any subsequent deaths were noted, and the autopsy findings, when available, were reviewed. Surviving patients were contacted, and 12 were willing to return for follow-up imaging, which consisted of plain radiography, real-time ultrasonography, colour Doppler imaging and contrast-enhanced computed tomography. Changes in filter position, the presence of thrombus and perforation of the vessel wall by the filter struts were documented.

RESULTS

All 10 patients who underwent filter insertion while in an intensive care unit (ICU) died, an average of 22 days after the procedure. Eleven other patients also died. Recurrent pulmonary embolism was not suspected in any of these patients, and five autopsies revealed no caval thrombosis. Imaging studies in 12 of the surviving patients revealed no occlusion of the inferior vena cava and no filter migration; however, the vena caval wall was perforated in all of these patients. Nonocclusive intrafilter thrombus was detected by colour Doppler imaging in three patients.

CONCLUSIONS

In this small group of patients the Bird's Nest filter was effective in preventing recurrent pulmonary embolism and caused less caval thrombosis than has previously been suspected, although intrafilter clot was found in 25% of the patients who underwent follow-up imaging. Colour Doppler imaging is the method of choice for detecting nonocclusive thrombus with this type of filter. Perforation of the caval wall was universal but not clinically symptomatic. Finally, guidelines should be established to ensure the cost-effective use of inferior vena caval filters in ICU patients.

The cisterna chyli: a potential mimic of retrocrural lymphadenopathy on CT scans

PURPOSE

To determine the normal appearance of the cisterna chyli and how it may mimic an enlarged retrocrural lymph node on computed tomographic (CT) images.

MATERIALS AND METHODS

CT scans were reviewed in 18 patients (17 with cancer, one with benign disease) who had tubular retrocrural structures of attenuation near that of water. The location, diameter, length, CT attenuation, duration of finding, change in size, and the status of intercurrent malignancy were recorded.

RESULTS

The cisterna chyli was variably located at T12-L1 (n=11), at T11-T12 (n=5), and at T-12 (n=2). The average length was 3 cm. The average CT attenuation was 12.5 HU. On serial scans in 14 patients, the average change in size was 2.2 mm despite progression or regression of malignant disease at other sites in 11 patients.

CONCLUSION

The cisterna chyli can mimic the appearance of an enlarged retrocrural lymph node. Proper identification depends on its characteristic location, tubular configuration, attenuation closer to that of water than soft tissue, and lack of substantial change in size despite changes in disease at other sites.

Detection of hepatocellular carcinoma by intraarterially enhanced ultrasonography with CO2 microbubbles. Comparison with DSA, dynamic CT, and Lipiodol CT

PURPOSE

To evaluate the diagnostic value of contrast-enhanced US with CO2 microbubbles (EU) for HCCs. Detectability was compared with DSA, dynamic CT, and Lipiodol CT.

MATERIAL AND METHODS

Forty-seven histologically proven HCCs detected with US were evaluated with EU, DSA, and dynamic CT. In 23 patients (35 lesions), Lipiodol CT was also performed. The size of the tumors ranged from 8 to 71 mm (average 28.1 mm); 24 lesions were smaller than 20 mm and 23 lesions were larger than 20 mm.

RESULTS

Overall detection was possible in 40 of 47 lesions (85%) by EU, in 32 of 47 (68%) by DSA, in 33 of 47 (74%) by dynamic CT, and in 27 of 35 (77%) by Lipiodol CT. In tumors smaller than 20 mm, detection was possible in 21 of 24 lesions (88%) by EU, 14 of 24 (58%) by DSA, 14 of 24 (58%) by dynamic CT, and 11 of 17 (65%) by Lipiodol CT.

CONCLUSION

EU has significant diagnostic value for detection of HCCs, particularly tumors smaller than 20 mm.

Detection of main renal artery stenosis using phase-contrast cine MR angiography

OBJECTIVE

The purpose of our study was to assess the ability of phase-contrast cine MR angiography to detect the presence of main renal artery stenosis.

SUBJECTS AND METHODS

We prospectively evaluated 75 hypertensive patients form main renal artery stenosis using phase-contrast cine MR angiography. Each main renal artery was evaluated as normal or abnormal. Thirty-seven of the 75 patients underwent conventional arteriography or intraarterial digital subtraction arteriography; these results were compared with the MR angiographic interpretations. Only those patients who had confirmatory arteriography were included in the statistical analysis.

RESULTS

Thirty-six main renal arteries interpreted as normal by MR angiography were found to be without a focal stenosis on invasive arteriography. MR angiography suggested 32 main renal artery stenoses; invasive arteriography showed 29 of these as stenoses. Three main renal arteries that were interpreted as having focal stenoses by MR angiography were shown to be not stenotic by invasive arteriography. Three other patients had diffusely narrowed main renal arteries bilaterally without a focal stenosis on MR angiography; bilateral proximal renal artery stenoses were seen at arteriography in two of these patients, and diffusely narrowed main renal arteries were seen in the third patient. Thus, the sensitivity of phase-contrast cine MR angiography for detecting a focal stenosis or abnormal main renal artery was 100% (95% confidence interval, 88-100%) and the specificity was 93% (95% confidence interval, 80-99%). The kappa coefficient was 0.85 with a standard error of 0.08.

CONCLUSION

Phase-contrast cine MR angiography had a high degree of accuracy and a high negative predictive value in detecting the presence of main renal artery stenoses and may be a good screening technique for renovascular hypertension.

Density enrichment and characterization of hematopoietic progenitors and stem cells from umbilical cord blood

Umbilical cord blood (UCB) is being used for hematopoietic rescue after myeloablative therapy in a rapidly growing number of patients. Recent developments of cord blood banking, ex vivo progenitor expansion and gene therapy techniques have raised the issue of efficient progenitor and stem cell enrichment procedures using UCB. We have used discontinuous density gradient techniques to analyze progenitor distribution in the mononuclear cell fraction of cord blood. This resulted in establishment of a highly reproducible, rapid, cost-effective single-step density separation method that generates a light density fraction, which when compared to conventional mononuclear cells has a high number of clonogenic progenitors, can be extensively expanded in vitro for up to 21 days and has the ability to sustain long-term hematopoiesis when inoculated on a preformed stromal layer. It can also serve as an efficient target for retrovirally mediated gene transfer, utilizing a vector expressing a mutated dihydrofolate reductase gene that confers methotrexate resistance.

Efficiency of discography followed by chemonucleolysis in the treatment of sciatica

One hundred and twenty-eight patients underwent discography in our department over a period of 3 years. Eighty-four of them were treated by chemonucleolysis. All the patients were punctured by a postero-lateral approach of the intervertebral disc under fluoroscopy. Although several contraindications to chemonucleolysis are known, in our study, only one case of spondylodiscitis was noted. Overall success rate was 72.6%. Twenty-three patients (27.4%) experienced similar or increased pain after treatment.

Use of a 22-gauge Whitacre needle to reduce the incidence of side effects after lumbar myelography: a prospective randomised study comparing Whitacre and Quincke spinal needles

In a prospective study lumbar iohexol myelography was performed in 107 consecutive patients, randomised for lumbar puncture with a Quincke or Whitacre spinal needle. All patients answered a questionnaire about possible side effects. Data from 100 patients (58 men, 42 women) were evaluated. In the Quincke group (n = 53), 23 (43%) reported no side effects. In the 30 patients who reported various side effects, post-dural puncture headache (PDPH) occurred in 22 (42%), of whom 9 had mild, 6 moderate and 7 (13%) severe cephalalgia, 18 (34%) reported increased low back pain/sciatica, 5 nausea and 7 dizziness. In the Whitacre group (n = 47), 33 (70%) had no side effects. PDPH was reported by 9 patients (19%), of whom 2 had mild, 6 moderate and only 1 (2%) severe cephalalgia, 4 (9%) reported increased low back pain/sciatica, 5 nausea and 4 dizziness. The conclusion drawn from this study is that lumbar myelography performed with the Whitacre spinal needle reduces postspinal side effects.

Coronary angiography by electron beam tomography

Electron Beam Tomography (EBT), a non-invasive imaging method with very high spatial and temporal resolution, is well suited for cardiac imaging. We established a protocol for the visualization of the coronary arteries by EBT and have so far evaluated the method in 88 patients. EBT imaging was performed using an Evolution scanner with a matrix of 512 x 512, a field of view of 15 cm and a slice thickness of 3 mm. After venous injection of contrast agent, 40 axial cross-sections of the heart were obtained triggered to the ECG at 80% of the R-R interval in inspiratory breathhold. With a lower threshold of 80 HU, 3D reconstructions of the heart and coronary arteries were rendered using shaded-surface display and maximum-intensity projection techniques. In all patients, the coronary arteries and, if present, aorto-coronary bypass grafts, were evaluated as to their visibility and presence or absence of haemodynamically relevant stenoses. All results were compared to the X-ray angiograms obtained by selective catheterization in a blinded manner. In 90% of cases, image quality was sufficient for evaluation. In 10% of the investigations, the EBT images could not be evaluated, mainly due to respiration artifacts. While the left anterior descending coronary artery was represented in very good image quality, the right coronary artery and left circumflex coronary artery showed decreased image quality due to motion artifacts and close correlation to venous structures such as the coronary sinus and atrial appendages. In a subgroup of 30 patients in which EBT results were compared to quantitative coronary angiography, the correlation of the vessel diameter in EBT and quantitative angiography was 0.82. Twelve out of 14 high-grade stenoses and 5/5 occlusions of the left anterior descending coronary artery as well as 3/4 highgrade stenoses and 1/2 occlusions of the right coronary artery and 2/4 high-grade stenoses of the left circumflex coronary artery were correctly identified. Nine patients were reinvestigated by EBT after successful angioplasty of high-grade coronary artery stenoses. The increase in vessel diameter could be documented in all cases. Twelve patients had a total of 28 aorto-coronary bypass grafts. Except for one mammarian artery graft which could not be evaluated due to small vessel lumen and clip artifacts, graft patency (21 cases) or occlusion (6 cases) was correctly diagnosed by EBT. EBT is a non-invasive method which permits the visualization of the coronary arteries. Stenoses of coronary artery bypass grafts and of the left anterior descending coronary artery can be reliably diagnosed, while reduced image quality, mainly due to faster vessel motion, impairs the results obtained for the right and left circumflex coronary artery.

The CT appearance of aortic transection

Aortic transection is a frequently fatal traumatic injury. Patients who survive the initial event require rapid diagnosis and treatment. To this end, enhanced CT of the chest has been used to detect both mediastinal hematoma and direct vessel injury [1-6]. This essay shows the CT features associated with aortic transection, particularly the direct signs.

MR hysterosalpingography in a rabbit model

Our objective was to evaluate the efficacy of MR imaging as compared with conventional hysterosalpingography (HSG) for the detection of fallopian tube patency after uterine injection of contrast material. Rabbit uterine horns (n= 18) were catheterized transvaginally. Five fallopian tubes were ligated and 11 were left unaltered. T1-weighted gradient-echo MR images were obtained before, during, and after injection of 1.0-3.0 mL of a dilute gadolinium-containing contrast agent. Corresponding conventional studies were performed with an equivalent volume of iohexol. Images were evaluated by two blinded readers. Observers agreed in all cases on the presence (n = 11) or absence (n = 5) of peritoneal spill with conventional HSG. Interpretation of MR HSG concurred with conventional HSG in 14 of 16 cases for each observer (P > .05). Reasons for misdiagnosis included small amounts of spill (n = 2), artifact (n = 1), and subtle spill between bowel loops (n = 1). Sensitivity and specificity for MR HSG were 95.5% and 70%, respectively, for the diagnosis of tubal patency/occlusions. No statistical difference was found between MR HSG and conventional HSG for the diagnosis of fallopian tube patency/obstruction. Potential advantages of MR HSG include no ionizing radiation, potentially diminished local contrast toxicity, superior visualization of uterine fibroids and endometriosis, and visualization of ovaries. We conclude that this technique warrants further study, including the use of a primate model to better simulate human anatomy.