Benefits of routine use of coronal and sagittal reformations in multi-slice CT examination of the abdomen and pelvis

AIM

To evaluate the usefulness of coronal and sagittal reformations from isotropic abdomino-pelvic computed tomography (CT) examinations.

METHODS

Fifty consecutive abdomino-pelvic CT examinations were reconstructed into two sets of axial source images: 0.9 mm section width with 0.45 mm reconstruction interval (isotropic) and 4 mm section width with 3 mm reconstruction interval. The isotropic dataset was reformatted into coronal and sagittal stacks with 4 mm section widths. Three readers independently reviewed the three image sets with 4 mm section widths. The coronal and sagittal reformations were compared with the axial images, in the same sitting, for depiction of lesions in various abdominal organs.

RESULTS

There was better visualization of lesions in the liver, kidneys, mesentery, lumbar spine, major abdominal vessels, urinary bladder, diaphragm and hips on the coronal reformations compared with source axial images (p<0.05). Sagittal reformations scored better than axial source images for showing lesions in the liver, thoracic spine, abdominal vessels, uterus, urinary bladder, diaphragm and hips (p<0.05). The coronal and sagittal series showed significant additional information in 23 and 17% of patients, respectively.

CONCLUSION

Radiologists should consider the routine review of at least one additional plane to the axial series in the interpretation of abdomino-pelvic CT studies.

Routine isotropic computed tomography scanning of the abdomen and pelvis

For 30 years, abdominal CT has been imaged and reviewed in the axial plane. It is now possible to carry out isotropic imaging of the whole abdomen and pelvis using a 40-channel scanner. This allows creation of coronal and sagittal reformats with the same image quality as the axial images. In this study, we present our experience of reviewing routinely coronal and, occasionally, sagittal reformats. We discuss situations where these nonaxial reformats are most beneficial.

Proximal small bowel intussusceptions in adults: CT appearance and clinical significance

BACKGROUND

According to the clinical literature, intestinal intussusception in adults is rare, is associated with a pathologic lead point, and is usually treated surgically. Nonobstructing small bowel intussusception has been reported as a transient finding on computed tomographic (CT) studies.

METHODS

We evaluated the radiographic and clinical findings in 24 patients who were found to have 26 proximal small bowel intussusceptions on abdominal CT scans performed for a variety of indications.

RESULTS

Twenty patients with intussusceptions had no evidence of small bowel obstruction. The transient and clinically insignificant nature of 22 intussusceptions in these 20 patients was proven radiologically (n = 14), surgically (n = 1), or by clinical follow-up (n = 7). These patients demonstrated a bowel-within-bowel pattern on multiple contiguous images and absence of strangulation or intestinal dilatation. No lead points were demonstrated in these patients. Three other patients had symptoms of low-grade small bowel obstruction and were treated conservatively. Extensive follow-up investigations showed no recurrence of intussusception or a lead point. One patient had high-grade obstructive intussusception with intestinal ischemia and required surgical resection of necrotic bowel.

CONCLUSIONS

Proximal small bowel intussusceptions are likely to be transient and nonobstructive and unlikely to have a significant lead point.

Evaluation of prospective living renal donors for laparoscopic nephrectomy with multisection CT: the marriage of minimally invasive imaging with minimally invasive surgery

Laparoscopic technique for excision of a kidney from a living donor has advantages over conventional open surgery, but operative visibility and surgical exposure are limited. Preoperative multisection computed tomography (CT) can provide necessary anatomic information in a minimally invasive procedure. A three-phase examination is suggested: (a) imaging from the top of the kidneys to the pubic symphysis with a section width of 2.5 mm and no contrast medium, (b) scanning of the kidneys and upper pelvis during the arterial phase of enhancement with a section width of 1.0 mm, and (c) scanning of the kidneys and upper retroperitoneum during the nephrographic phase of enhancement with a section width of 1.0 mm. Emphasis in this article is placed on analysis of the venous anatomy because most radiologists are unfamiliar with the anatomic variations. Conventional radiography of the abdomen and pelvis is performed after CT to evaluate the collecting system and ureters and to provide a lower total radiation dose than if CT were used. Of several postprocessing techniques that may be used, the authors prefer maximum intensity projection for arterial evaluation and multiplanar reformatting for venous evaluation.

Stent grafting of abdominal aortic aneurysms: pre-and postoperative evaluation with multislice helical CT

Endovascular stent grafting of abdominal aortic aneurysms is a new technique that may replace open surgery in selected cases. Pre-and postoperative angiography can be replaced by helical CT. This pictorial essay describes and illustrates the use of multislice helical CT where maximum intensity projection and multiplanar reformats play a central role in the evaluation.

Multisection CT: scanning techniques and clinical applications

Multisection computed tomography (CT) was introduced in 1992 with the advent of dual-section-capable scanners and was improved in 1998 following the development of quad-section technology. With a recent increase in gantry speed from one to two revolutions per second, multisection CT scanners are now up to eight times faster than conventional single-section helical CT scanners. The benefits of quad-section CT relative to single-section helical CT are considerable. They include improved temporal resolution, improved spatial resolution in the z axis, increased concentration of intravascular contrast material, decreased image noise, efficient x-ray tube use, and longer anatomic coverage. These factors substantially increase the diagnostic accuracy of the examination. The multisection CT technique has enabled faster and superior evaluation of patients across a wide spectrum of clinical indications. These include isotropic viewing, musculoskeletal applications, use of multiplanar reformation in special situations, CT myelography, long coverage and multiphase studies, CT angiography, cardiac scoring, evaluation of brain perfusion, imaging of large patients, evaluation of acute chest pain or dyspnea, virtual endoscopy, and thin-section scanning with retrospective image fusing. Multisection CT is superior to single-section helical CT for nearly all clinical applications.

Classification and management of perforations complicating endoscopic sphincterotomy

BACKGROUND

The management of perforations after endoscopic sphincterotomy (ES) is controversial. The purpose of this study was to analyze the treatments and outcome of patients with ES perforations.

METHODS

Between January 1994 and July 1998, in a series of 6040 endoscopic retrograde cholangiopancreatographies, 2874 (48%) ESs were performed: 40 patients (0.6%) with perforation were identified and retrospectively reviewed.

RESULTS

All patients (n = 14) with guidewire perforation (group I) were recognized early, managed medically, and discharged after a mean hospital stay of 3.5 days. Twenty of 22 patients with periampullary perforation (group II) were identified early; 18 patients (90%) had aggressive endoscopic drainage, and none required operation. Of the 2 patients identified late, 1 patient required operation and subsequently died. Mean hospital stay for this group was 8.5 days. Only 1 of 4 patients with duodenal perforations (group III) was identified early; all required operation; 1 patient died, and the mean hospital stay was 19.5 days.

CONCLUSIONS

ES perforation has 3 distinct types: guidewire, periampullary, and duodenal. Guidewire perforations are recognized early and resolve with medical treatment. Periampullary perforations diagnosed early respond to aggressive endoscopic drainage and medical treatment. Postsphincterotomy perforations diagnosed late (particularly duodenal) require surgical drainage, which carries a high morbidity and mortality rate.

Screening for hepatocellular carcinoma in patients with advanced cirrhosis

OBJECTIVE

Most available data on screening for hepatocellular carcinoma (HCC) in patients with cirrhosis originate from Asia and Europe. These data may not be applicable to patients from the United States because of geographic variation in the underlying etiology and other factors. Our aim was to assess the risk of HCC in U.S. patients with cirrhosis undergoing standardized screening.

METHODS

All cirrhotic patients evaluated for liver transplantation at our institution from January 1, 1994-December 31, 1997 were included in this study. The screening strategy included initial screening, which was offered to all patients and consisted of alpha-fetoprotein (AFP), abdominal ultrasound, and computed tomography (CT) scan, and extended screening, which was performed only on transplant-eligible patients and consisted of semiannual AFP and ultrasound.

RESULTS

During the study period, 285 patients with cirrhosis were evaluated for transplantation and underwent initial screening. Of these, 166 were eligible for transplantation and underwent extended screening during a median follow-up of 15 months (range 6-42 months). Twenty-seven HCC were found, 22 during initial screening and five during extended screening. The cancer-free proportions of the cohort who underwent extended screening at 1, 2, and 3.5 yr were 98.6% +/- 1.4%, 96.4 +/- 1.8%, and 77.1% +/- 1.7%, respectively (mean +/- SE). Hepatitis C, either alone or in part, was the etiology in 63% of patients with HCC. The sensitivity of CT scan (88%) was significantly higher than AFP >20 ng/ml (62%) and ultrasound (59%) for detecting HCC (p < 0.001).

CONCLUSIONS

In patients with established cirrhosis, the risk of detecting HCC is maximal at the baseline screening (7%). Hepatitis C was the most common etiology for cirrhosis in study. In U.S. patients with established cirrhosis, CT scan exhibited higher sensitivity for detecting HCC than ultrasound or AFP.

Classification and management of perforations complicating endoscopic sphincterotomy

BACKGROUND

The management of perforations after endoscopic sphincterotomy (ES) is controversial. The purpose of this study was to analyze the treatments and outcome of patients with ES perforations.

METHODS

Between January 1994 and July 1998, in a series of 6040 endoscopic retrograde cholangiopancreatographies, 2874 (48%) ESs were performed: 40 patients (0.6%) with perforation were identified and retrospectively reviewed.

RESULTS

All patients (n = 14) with guidewire perforation (group I) were recognized early, managed medically, and discharged after a mean hospital stay of 3.5 days. Twenty of 22 patients with periampullary perforation (group II) were identified early; 18 patients (90%) had aggressive endoscopic drainage, and none required operation. Of the 2 patients identified late, 1 patient required operation and subsequently died. Mean hospital stay for this group was 8.5 days. Only 1 of 4 patients with duodenal perforations (group III) was identified early; all required operation; 1 patient died, and the mean hospital stay was 19.5 days.

CONCLUSIONS

ES perforation has 3 distinct types: guidewire, periampullary, and duodenal. Guidewire perforations are recognized early and resolve with medical treatment. Periampullary perforations diagnosed early respond to aggressive endoscopic drainage and medical treatment. Postsphincterotomy perforations diagnosed late (particularly duodenal) require surgical drainage, which carries a high morbidity and mortality rate.

An initial experience with screening for colon polyps using spiral CT with and without CT colography (virtual colonoscopy)

BACKGROUND

Computed tomographic (CT) colography (virtual colonoscopy) is a new imaging method for detection of colon polyps and cancer.

OBJECTIVE

To evaluate the sensitivity of CT colography for polyp detection in a population without symptoms that included persons without colon neoplasia and with radiologists blinded to colonoscopic findings.

METHODS

Forty-six persons without symptoms underwent spiral CT followed by same-day colonoscopy with subsequent inspection of two-dimensional axial CT images, interactive multiplanar images, and surfaced and volume-rendered images of the colon (three-dimensional CT colography).

RESULTS

Three-dimensional CT colography was superior to two-dimensional axial imaging for detection of colon polyps. Three-dimensional CT colography depicted 1 of 4 (25%) adenomas 2 cm in diameter or larger, 6 of 10 (60%) adenomas 1 to 1.9 cm, 6 of 14 (43%) 6 to 9 mm, and 7 of 65 (11%) 5 mm in diameter or smaller. Three-dimensional CT colography showed a polyp that might have led to colonoscopy in 3 of 4 (75%) patients whose largest adenoma was 2 cm or larger, 5 of 6 (83%) patients with largest adenoma 1 to 1.9 cm, 3 of 7 (43%) patients with largest adenoma 6 to 9 mm, and 4 of 16 patients (25%) with largest adenoma 5 mm or smaller. Large, flat adenomas of the right colon were difficult to identify with three-dimensional CT colography. The specificity of three-dimensional CT colography for patients with adenomas 1 cm in diameter or larger was 89%. Examination of patients with missed adenomas after unblinding indicated that meticulous bowel preparation and adequate distention are critical to accurate interpretation. Perceptual errors were common.

CONCLUSIONS

CT colography as performed in this study is not adequate as a colorectal cancer screening test. Several technical factors that appear critical to accurate performance of CT colography are defined.

Temporal bone: comparison of isotropic helical CT and conventional direct axial and coronal CT

OBJECTIVE

The objective of the study was to compare helical CT (with reformation of coronal images from the axial data set) with conventional direct axial and coronal CT of the temporal bones.

SUBJECTS AND METHODS

Nineteen patients underwent both conventional 1-mm direct axial and coronal CT and helical 0.5-mm axial CT. The helical data set was reconstructed at 0.2-mm increments, and axial and coronal images were reconstructed in a plane similar to that of the conventional study, with a slice width of 0.5 mm and 0.5-mm increments. Forty small structures were evaluated independently by three observers, who were unaware of the method of imaging. Observers graded the 40 structures using a modified Likert scale. The graded differences between the two techniques were evaluated using a paired t test. Correlation between observers' gradings was evaluated using analysis of variance.

RESULTS

The helical CT technique scored significantly higher than the conventional technique for many individual structures and groups of structures (scutum [p = .041], stapes footplate [p = .006], stapes crura [p = .004], oval window [p = .026], crista falciformis [p = .006], whole temporal bone [P = .012], middle ear [p = .033], inner ear [p = .021], ossicles [p = .044], and stapes [p = .010]). The correlation coefficient among observers was .91 for the whole temporal bone.

CONCLUSION

Helical CT using 0.5-mm technique and reconstruction produces diagnostic images comparable with or superior to conventional 1-mm technique because helical CT can obtain thinner slices.

Thermoacoustic CT with radio waves: a medical imaging paradigm

The authors evaluated images obtained with a prototypic thermoacoustic computed tomographic (CT) scanner constructed for use at 434 MHz, a promising radio frequency for detecting breast cancer. In one excised porcine kidney, acoustic energy emanating from the kidney was detected with transducers. The resultant electric signals were used to create a three-dimensional data set. Two-dimensional images reconstructed in multiple planes were compared with state-of-the-art T1- and T2-weighted magnetic resonance images. The renal outline, parenchyma, and collecting system were clearly delineated on the thermoacoustic CT images.

Measurement of liver volume using spiral CT and the curved line and cubic spline algorithms: reproducibility and interobserver variation

BACKGROUND

The purpose of this article was to evaluate the accuracy and reproducibility of spiral computed tomography (CT) and the curved line and cubic spline algorithms in measuring liver volume.

METHODS

Spiral CT was performed in phantoms, cadaveric liver specimens, and 35 live human subjects (19 healthy volunteers and 16 patients). Images were transferred to a workstation, and volumes were measured by two observers. One observer repeated the measurements at a separate sitting.

RESULTS

The correlation between the CT measurement and the gold standard measurement of the cadaveric livers was very strong (r = 0.94). For the live human subjects, the intraobserver and interobserver correlations were extremely high (r = 0.999 and 0.997, respectively). The mean difference in liver volume measurements between the separate observations was 1%.

CONCLUSION

The accuracy and reproducibility of this method of assessing liver volume are very high.

Gender differences in alcohol metabolism: relationship to liver volume and effect of adjusting for body mass

BACKGROUND & AIMS

Alcoholic liver disease purportedly develops more readily in women than in men. Some studies have demonstrated faster rates of alcohol elimination in women. This study examined whether gender differences in alcohol metabolism are related to differences in liver volume and/or differences in lean body mass.

METHODS

Ten men and 10 women had alcohol elimination rates determined by clamping of the breath alcohol concentration at 50 mg/dL by means of a constant rate of intravenous infusion of 6% ethanol. Liver volume was determined by computed tomography.

RESULTS

Mean alcohol elimination rate and mean computed liver volume were not significantly different in men and women. Lean body mass was 42% greater in men than in women. Consequently, the calculated alcohol elimination rate and liver volume per kilogram of lean body mass were 33% and 38% higher in women than in men, respectively. When the alcohol elimination rate was calculated per unit liver volume, no gender-related difference was found.

CONCLUSIONS

Women have greater clearance of ethanol per unit lean body mass, confirming previous oral alcohol administration studies. Women have approximately the same liver volume as men, explaining the equivalent alcohol elimination rates seen when men and women are compared on the basis of liver size.

Objective measurement of motion in patients undergoing spiral CT examinations

PURPOSE

To develop and evaluate an objective measurement of patient motion during spiral computed tomography (CT).

MATERIALS AND METHODS

An acrylic rod was attached along the length of the torso in 109 patients (56 women, 53 men; age range, 21-79 years; mean age, 51 years) who underwent abdominal spiral CT examinations. Subjective evaluation of motion was graded on a five-point scale by two radiologists. Objective measurements of motion were determined by means of computer reconstruction of the rod in three dimensions and calculation of the deviation of the rod from its estimated position in the motionless state with time.

RESULTS

Complete data were available in 98 patients. Subjective and objective measurements of patient motion showed a moderately high Spearman correlation coefficient of .49 (P < .001). The correlation between either observer and objective measurements was similar to the correlation between one observer and the other.

CONCLUSION

This objective technique for assessing patient motion correlated well with subjective methods and may be useful in evaluating scanning parameters that may affect patient motion and hence scan quality.

Identification of clinical stage A nonseminomatous testis cancer patients at extremely low risk for metastatic disease: a combined approach using quantitive immunohistochemical, histopathologic, and radiologic assessment

PURPOSE

To evaluate previously determined predictors of metastasis in low-stage testis cancer in a consecutive group of clinical stage A patients.

PATIENTS AND METHODS

Ninety-one consecutive clinical stage A nonseminomatous germ cell tumor (NSGCT) patients who underwent primary nerve-sparing retroperitoneal lymph node dissection (NSRPLND) had orchiectomy specimens and computed tomographic (CT) scans evaluated blindly in a quantitative fashion. These scores were then correlated with pathologic stage using previously determined paradigms.

RESULTS

Using volume of embryonal carcinoma in the orchiectomy specimen, lymph node diameters in the primary landing zones and MIB-1 staining of the orchiectomy specimen, 41 patients were classified as low risk for metastasis. Forty of these 41 had pathologic stage A disease at RPLND.

CONCLUSION

These parameters can identify a low-risk group of patients for metastasis who can be rationally offered surveillance.

Comparison of ultrasound-fine needle aspiration and computed tomography in patients undergoing elective neck dissection

BACKGROUND

Ultrasound of the neck with fine needle aspiration (US-FNA) of suspicious lymph nodes has potential advantages over other radiologic techniques as a screening method for the NO neck in head and neck cancer.

METHODS

Twenty-five patients with head and neck cancer who underwent both US of the neck with FNA of any suspicious lymph nodes and neck computed tomography (CT) prior to elective neck dissection were studied. The majority of patients had squamous cell carcinoma (SCC) of the upper aerodigestive tract. Histopathologic results of the neck specimens were compared with each screening technique (palpation, US, US-FNA, CT).

RESULTS

Computed tomography (87.9%) and US-FNA (84.9%) had similar overall accuracy in terms of screening the NO neck in our study and were superior to palpation (69.7%) and US alone (72.7%). Specificity was 100% for both CT and US-FNA, with a sensitivity of 60% for CT and 50% for US-FNA. Ultrasound-FNA and CT showed false-negative examinations on virtually the same cases.

CONCLUSIONS

Overall, US-FNA was comparable to CT in screening the NO neck in our study. The choice of which modality to employ for imaging the clinically negative neck depends on a number of factors, including the location and clinical extent of the primary tumor as well as the experience and preference of the head and neck surgeon and radiologist.

Value of helical computed tomography, angiography, and endoscopic ultrasound in determining resectability of periampullary carcinoma

BACKGROUND

High-quality preoperative radiographic evaluation is crucial in selecting patients with periampullary carcinomas who are candidates for surgical exploration and tumor resection while minimizing the rate of unnecessary laparotomy.

METHODS

Twenty-one consecutive patients were prospectively investigated using helical computed tomography (CT) scanning, endoscopic ultrasonography (EUS), and selective visceral angiography (SVA) to determine tumor resectability. All patients were explored and resectability determined.

RESULTS

Helical CT had a sensitivity of 63%, a specificity of 100%, and an overall accuracy of 86%. EUS had a sensitivity of 75%, a specificity of 77%, and an overall accuracy of 76%. SVA had a sensitivity of 38%, a specificity of 92%, and an overall accuracy of 71%.

CONCLUSIONS

Helical CT scanning is the best preoperative imaging test to determine tumor resectability. EUS is more sensitive than CT for tumor detection, but underestimates resectability. SVA is no longer helpful in the preoperative evaluation of these malignancies.

Coronary calcium measurements by double helical computed tomography. Using the average instead of peak density algorithm improves reproducibility

RATIONALE AND OBJECTIVES

Coronary calcium (CC) measured by fast computed tomography (CT) was proposed recently as a noninvasive method of monitoring the coronary atherosclerotic process. Assessment of the reproducibility of CC measurements (mainly interstudy variability) is essential for consistent interpretation of serial studies.

METHODS

The authors scanned 74 patients (50 men and 24 women) twice on the same day to determine the interstudy variability of a new scoring algorithm, using the average instead of conventional peak CT density values.

RESULTS

Nineteen patients had no calcium on either scan. In the remaining 55 patients, interstudy variability was decreased by 31% using the average algorithm (32%-23%; P < 0.001).

CONCLUSIONS

Using the average instead of conventional peak density score provides better reproducible measurements of calcium by double helical CT.

Median arcuate ligament syndrome with multivessel involvement: diagnosis with spiral CT angiography

Intestinal angina may be caused by compression of the celiac artery by the median arcuate ligament of the diaphragm. Aortography can suggest the diagnosis, but the diaphragm cannot be visualized by this examination. We report a symptomatic woman in whom spiral computed tomography-guided angiography demonstrated stenosis of the celiac artery, superior mesenteric artery, and both renal arteries due to diaphragmatic compression. Surgery was beneficial.

Radiation exposure to patients and personnel during interventional ERCP at a teaching institution

BACKGROUND

This study was designed to determine the radiation dose to patients and personnel during ERCP procedures.

METHODS

Phantom studies were performed to compare dosimetry for two image capture systems and to determine the effectiveness of shielding in reducing stray radiation. Radiation techniques and dosimetry were recorded in 72 patients undergoing ERCP.

RESULTS

Phantom studies indicated that increasing fluoroscopy voltage from 75 to 96 kV decreased entrance dose by 50%. Image capture by digital radiography decreased radiation exposure by 66%. Shielding decreased stray radiation exposure by 93%. All patients underwent cholangiography (n = 71) and/or pancreatography (n = 53). The mean number of interventional ERCP procedures performed per patient was 1.8 (range, 0 to 6). The mean measured patient entrance dose was 80 mGy (8 R; range, 0.2 to 73 R); however, the calculated mean entrance dose (based on measured intensifying screen doses) may have been as high as 3000 mGy (30 R; range, 0.8 to 300 R). Measured patient exposure increased with fluoroscopy time (r = 0.9) and with the number of interventions performed (r = 0.3). The mean dose to personnel was estimated at 0.04 mR.

CONCLUSIONS

The patient radiation dose depended most on fluoroscopy time. The dose may be lowered by minimizing fluoroscopy time, using higher voltage and lower current for fluoroscopy, and using digital radiography for documentation. Personnel were adequately protected.

Spiral CT angiography of the aorta

Imaging of the aorta and its branches has benefitted greatly from the development of spiral CT techniques, which are relatively fast and noninvasive. The volumetric acquisition of spatial information has permitted the computer to reformat images for inspection of the vessels by several methods from an infinite number of viewing angles. Most aortic diseases-including congenital anomalies, dissection, aneurysm, trauma, inflammation, infection, and thromboembolic disease-can be depicted with this technology. In selected cases, spiral CT may be the only imaging modality needed for the surgical planning of aortic repair. This report discusses the CT angiography technique, its application to a variety of disease states, its role relative to other imaging modalities, and guidelines for patient selection.

Measurement of coronary artery calcium with dual-slice helical CT compared with coronary angiography: evaluation of CT scoring methods, interobserver variations, and reproducibility

OBJECTIVE

This study was performed to evaluate new scoring methods for quantitating coronary artery calcifications with helical CT and to compare the results with those of quantitative coronary angiography in patients with suspected coronary artery disease.

SUBJECTS AND METHODS

Unenhanced dual-slice helical CT and coronary angiography were performed within 24 hr of each other in 101 patients with symptoms of coronary artery disease. Coronary artery calcifications with a density above 90 H were identified on each slice and, with the same regions of interest, quantitative scoring was performed at thresholds of 90 H (new) 130 H (old). Two mathematical algorithms (one new and one old) were evaluated for both thresholds (yielding four scoring systems). By CT imaging, we defined disease as a score of greater than zero. By angiography, we defined disease as a 50% or greater reduction in the luminal diameter of any major vessel. Interobserver variations in calcification scoring were evaluated. Seventeen of our patients. also underwent a second, consecutive CT scan to determine reproducibility.

RESULTS

With the new threshold and the new algorithm, the sensitivity, specificity, and accuracy of helical CT in predicting disease were 88%, 52%, and 76%, respectively. We found a moderate positive association between the total CT calcification score and the number of stenotic coronary arteries at angiography (Pearson's correlation coefficient, .43; p = .05 [analysis of variance]). The accuracy and the area under the receiver operating characteristic curve were higher with the new threshold and the new algorithm. Interobserver agreement in calcification scoring was high (intraclass correlation coefficient, .99 [n = 85]), as was reproducibility (intraclass correlation coefficient, .94 [n = 17]). Reproducibility was higher when scoring was based on the new threshold and the new algorithm.

CONCLUSION

The quantity of coronary artery calcifications as measured by helical CT correlated positively with obstructive coronary artery disease as measured by angiography. Interobserver agreement and reproducibility were excellent. A new scoring method showed promise.

Comparison of spiral CT scan and arteriography for evaluation of renal and visceral arteries

Renal and visceral artery images obtained concurrently with spiral CT and conventional arteriography were compared for 32 patients. Indications for imaging were occlusive disease (n = 12), aneurysmal disease (n = 9), and renal or visceral artery disease (n = 11). Conventional arteriography enabled visualization of 64 renal arteries and 15 accessory renal arteries. Lateral aortograms obtained in 15 patients enabled visualization of 14 superior mesenteric (SMA) and 14 celiac arteries. Spiral CT enabled visualization of 60 renal arteries, 12 accessory renal arteries, 27 SMAs, and 22 celiac arteries. Calcification or a disparity in timing of contrast material injection and scanning prevented visualization of the celiac artery in 10 patients and the SMA in four patients. With conventional arteriography as the standard for comparison, spiral CT had a sensitivity of 67% and a specificity of 95% for depiction of at least 75% stenosis in the main renal artery. By means of the Pearson correlation coefficient, significant correlation (p < 0.001) was confirmed between spiral CT and arteriography for evaluation of stenosis of the main renal artery, SMA, and celiac artery. This early experience suggests that spiral CT may be useful in evaluation of renal and visceral arteries and their relationship to aortic disease.

Improved accuracy of computerized tomography based clinical staging in low stage nonseminomatous germ cell cancer using size criteria of retroperitoneal lymph nodes

PURPOSE

We evaluated the significance of retroperitoneal lymph nodes detected by computerized tomography (CT) of low stage nonseminomatous germ cell tumor patients.

MATERIALS AND METHODS

A blind retrospective review of 143 CTs of low stage nonseminomatous germ cell tumor revealed pathological stage A disease on 89 (62.2%) and pathological stage B disease on 54 (37.8%). A multivariate logistic regression model was used to evaluate the relationships between diameter of the retroperitoneal nodes detected in these CTs and pathological stage.

RESULTS

Based on this model, as the diameter of the nodes increased within a 0 to 25 mm. range, the likelihood of pathological stage B disease increased in a continuous fashion. Using a 3 mm. threshold to define nonmetastatic nodes the sensitivity and negative predictive value of CT based staging was 90%.

CONCLUSIONS

This measurement scheme improves the accuracy of staging compared to conventional methods.

Hydrocele of the canal of Nuck: ultrasound appearance

Swelling in the inguinal region of a woman may result from a number of conditions, including inguinal hernia, tumor (lipoma, leiomyoma, sarcoma), cyst, abscess, adenopathy, or hydrocele of the canal of Nuck. It may be difficult to make a specific diagnosis based upon the history and physical examination alone. This report describes a symptomatic woman in whom ultrasound was helpful in diagnosing a hydrocele of the canal of Nuck, which is the female counterpart of a spermatic cord hydrocele in the male. The ultrasound findings are described.

Duplex Doppler endosonography in the diagnosis of splenic vein, portal vein, and portosystemic shunt thrombosis

BACKGROUND/AIMS

Endoscopic ultrasonography is a promising procedure for imaging mesenteric vascular structures.

METHODS

Duplex and color Doppler endosonography were used to prospectively evaluate 20 asymptomatic paid volunteers. Subsequently, 11 patients with nondiagnostic transabdominal ultrasound and suspected thrombosis of the splenic and/or portal veins or a portosystemic shunt were evaluated with duplex endosonography. The final diagnosis was based on CT, angiography, and/or surgery or autopsy findings in 9 of 11 patients.

RESULTS

In normal volunteers, mesenteric vessel flow velocities and diameters were similar to previously described values. In 10 of the 11 patients with failed transabdominal ultrasound, duplex endosonography was able to provide the correct diagnosis (accuracy of ultrasound 0% versus EUS 91%, p < .001). Mean portal vein diameter was greater in the patient group than in the normal volunteers (18.5 mm versus 10.7 mm, p < .001) and all of the normal volunteers had a portal vein diameter less than 13 mm. No complications were experienced.

CONCLUSION

Duplex endosonography allows visualization of the intra-abdominal vasculature and can be considered when transabdominal ultrasound is nondiagnostic in patients with suspected thrombosis of their splenic vein, portal vein, or portosystemic shunt. EUS is able to identify indirect findings of portal hypertension including portal vein enlargement and venous collaterals.

Color Doppler flow imaging for deep venous thrombosis screening in patients undergoing pelvic lymphadenectomy and radical retropubic prostatectomy for prostatic carcinoma

Patients undergoing pelvic lymphadenectomy and radical retropubic prostatectomy are traditionally considered to be at high risk for postoperative venous thromboembolic complications. A prospective deep venous thrombosis screening regimen was initiated at our medical center in 1990 following 2 cases of fatal pulmonary embolism that occurred after hospital discharge. During a 3-year period 245 consecutive patients undergoing radical retropubic prostatectomy for prostate cancer were screened postoperatively for lower extremity deep venous thrombosis using ultrasound duplex scanning with color Doppler flow imaging. The results were correlated only with the development of clinical deep venous thrombosis. No additional diagnostic modalities were used to confirm a normal venous system in asymptomatic patients. Venous thromboembolic complications were encountered in 9 of the 245 patients (3.6%). In 2 patients deep venous thrombosis was associated with nonfatal pulmonary embolism. Only 2 of the 9 cases of deep venous thrombosis were detected by color Doppler flow imaging screening. The striking decrease in the incidence of deep venous thrombosis following radical prostatectomy in the last decade and the low yield of screening at a single point in time may warrant reconsideration of the need for deep venous thrombosis screening among patients undergoing pelvic lymphadenectomy and radical retropubic prostatectomy for prostate cancer.

The role of spiral (helical) computerized tomography with three-dimensional reconstruction in pediatric solid tumors

The ability to accurately assess tumor size and orientation to surrounding vital structures is an important consideration during preoperative evaluation. The authors report on nine children with solid tumors (hepatoblastoma [1], neuroblastoma [2], adrenal cortical carcinoma [2], liver adenoma [1], primitive neuroectodermal tumor [PNET] [1], and stage V Wilms' tumor [2]) for whom tumor resectability was questioned because of the tumors' close proximity to major blood vessels (noted through conventional radiographic imaging). The children had scanning with spiral volumetric acquisition computerized tomography, (CT) which obtains images during continuous rotation of the x-ray source while the patient moves at a constant velocity through the gantry. This technique is rapid (18 to 30 seconds), and is similar with respect to radiation exposure; little or no sedation is required, and the contrast dose is lower than that of conventional CT. Three-dimensional reconstruction of spiral CT imaging provided useful information that allowed successful resection in all nine cases. The authors suggest that spiral CT may become an important imaging modality in the preoperative evaluation of pediatric solid tumors and that further evaluation of this new methodology is warranted.

Intravenous cholangiography with helical CT: comparison with endoscopic retrograde cholangiography

PURPOSE

To determine whether helical computed tomography (CT) performed during intravenous cholangiography can provide useful images of the biliary tree and to compare this technique with endoscopic retrograde cholangiography (ERC).

MATERIALS AND METHODS

Eighteen adult patients with clinically suspected biliary disease who were referred for ERC were first examined with helical CT cholangiography performed 75 minutes after intravenous infusion of 100 mL of 10.3% iodipamide meglumine.

RESULTS

Helical CT cholangiography revealed good opacification of the biliary tree in 13 of 14 patients with serum bilirubin levels less than 2 mg/dL (34 mumol/L) and poor opacification in three of four patients with levels greater than 2 mg/dL. In six of seven patients with choledocholithiasis, the diagnosis was made by means of helical CT cholangiography.

CONCLUSION

Helical CT cholangiography may be a clinically useful method for visualization of the biliary tree in some patients with suspected biliary disease with normal bilirubin levels and in patients in whom attempts at ERC fail.

Spiral CT evaluation of the trachea and bronchi

OBJECTIVE

We report two cases in which spiral CT with three-dimensional (3D) reconstruction was used to evaluate abnormalities of the trachea and bronchi.

MATERIALS AND METHODS

Two patients with known airway abnormalities, one with a carinal tumor and the other with a postoperative bronchial stenosis, had spiral CT of the chest performed. Images were reconstructed in the coronal plane as well as using a curved planar reformat and shaded surface display.

RESULTS

Spiral CT with 3D reconstruction provided excellent anatomic definition of the central airway abnormalities. In our two cases the information provided was used in both the clinical assessment and treatment planning of the patients.

CONCLUSION

Spiral CT was useful in the evaluation of two patients with central airway abnormalities. Further investigation into applications of spiral CT for the evaluation of the central airways appears warranted.

Experimental high-frequency ultrasound can detect graft rejection after small bowel transplantation

Early diagnosis of graft rejection after small bowel transplantation (SBT) can allow prompt institution of vigorous immunosuppressive therapy, with resultant reversal of the rejection process. The current method for graft monitoring is random mucosal biopsy from a stomal site or through an endoscope. However, because early rejection often has a patchy distribution, it could be missed by random biopsy. We hypothesized that the pathological process of rejection would alter acoustic impedance of the tissue and thus change the ultrasonic patterns of the graft intestinal wall. If this hypothesis is correct, then high-frequency endoscopic ultrasound (US) could be used to monitor the entire transplanted bowel and guide the biopsy, with improved yields. This hypothesis was tested in a rat orthotopic SBT model. Sixty-two intestinal specimens (9 isografts, 12 allografts treated with cyclosporine A [CsA], 22 untreated allografts, and 19 intestines from normal rats) were collected for in vitro transluminal US imaging (30 MHz) and histopathologic study. The echo pattern of normal rat intestinal wall consisted of five echo layers that correlated spatially with the histological layers: the innermost hyperechoic layer 1, plus hypoechoic layer 2, corresponded to the mucosa; hyperechoic layer 3, the submucosa; anechoic layer 4, the muscularis propria; and hyperechoic layer 5, the serosa. The isografts and CsA-treated allografts were identical histologically and ultrasonically to normal intestine. However, the echo patterns of the untreated allografts had progressive loss of architectural stratification, with worsening rejection. The change began with patchy indistinctness and disruption of hyperechoic layers 1, 3 and 5, and progressed to total obliteration of the layers, with the intestinal wall becoming a nonstratified hypoechoic structure.(ABSTRACT TRUNCATED AT 250 WORDS)

Ultrasound-guided pediatric liver transplant biopsy using a spring-propelled cutting needle (biopsy gun)

Biopsy is the best way to diagnose allograft rejection, the most common complication following liver transplantation. The authors reviewed 99 consecutive ultrasound-guided cutting needle biopsies in 19 infants and children. Conscious sedation was used with 95 biopsies. General anesthesia was used with four biopsies, all in patients undergoing percutaneous biliary procedures at the same time. Ninety-eight biopsies were diagnostic. Only one major complication occurred: biloma. Ultrasound-guided cutting needle biopsy of pediatric liver transplant patients can be performed safely and efficaciously.

Prospective evaluation of endoscopic ultrasonography and endoscopic retrograde cholangiopancreatography in patients with chronic abdominal pain of suspected pancreatic origin

Twenty asymptomatic paid volunteers (13 females, 7 males, mean age 34 years, range 21-52 years), underwent endoscopic ultrasonography (EUS) to assess variation in the appearance of ductular and parenchymal features of the pancreas. Following this investigation, 69 patients with chronic abdominal pain of suspected pancreaticobiliary origin were evaluated with EUS followed by endoscopic retrograde cholangiopancreatography (ERCP) and in 16 patients secretin stimulated intraductal pure pancreatic juice (PPJ) collection. Thirty patients were found to have chronic pancreatitis based on clinical, ERCP and/or PPJ data, and EUS was abnormal in 24 of these individuals. All of the 19 patients with abnormal pancreatograms also had an abnormal EUS. Twenty-two of the 30 patients with chronic pancreatitis had early disease (no or minimal changes on ERCP). In this subgroup of patients, the sensitivity of EUS was 86% versus 50% for ERCP (p = 0.01). For all patients, the sensitivity, specificity and accuracy of EUS in diagnosing chronic pancreatitis was 80%, 86% and 84% respectively. Using logistic regression analysis eight EUS features were found to be indicative of chronic pancreatitis including echogenic foci within the gland, focal regions of reduced echogenicity within the gland, increased thickness/echogenicity of the main pancreatic duct (MPD) wall, accentuation of the gland's lobular pattern, cysts, an irregular contour or dilation of the MPD and side branch dilation (p < or = 0.05). Generation of a receiver operating characteristic curve to assess the sensitivity and specificity of EUS in diagnosing chronic pancreatitis based on the number of abnormal findings demonstrated that sensitivity and specificity were optimal when three or more abnormal parenchymal and/or ductular features were found. These results suggest that EUS can play an adjunctive role to ERCP and PPJ in the diagnosis of early chronic pancreatitis.

Percutaneous transhepatic drainage of the nondilated biliary system

PURPOSE

The authors sought to develop a safe, efficacious technique for percutaneous transhepatic drainage of nondilated biliary systems.

PATIENTS AND METHODS

Twenty-three drainage procedures were performed on 14 consecutive patients with nondilated ducts. Fourteen procedures were carried out for primary placement of a transhepatic biliary drain, eight for placement of a second drain, and one for placement of a third drain. Drainage catheter access into the biliary tree was gained via direct puncture of a peripheral duct (fourth order or smaller branch) in four procedures. In the remaining 19 procedures, peripheral duct punctures were facilitated by retrograde passage of a 5-F catheter from a previous, remote percutaneous access site into the fourth-order duct to be punctured. Nine of these 19 duct punctures were facilitated by the use of a nitinol Goose Neck snare passed through the intraductal catheter.

RESULTS

Of the access methods used, the nitinol snare technique was the fastest. Successful peripheral access was achieved in all patients without bleeding complications. One patient developed symptoms of bacteremia, which resolved within 12 hours with antibiotic therapy and external biliary drainage.

CONCLUSION

Percutaneous peripheral access can be achieved safely in the nondilated biliary tree and can obviate surgery for some patients and facilitate future interventions.

Sonographic and computed tomography characteristics of liver ablation lesions induced by high-intensity focussed ultrasound

RATIONALE AND OBJECTIVES

The authors have previously demonstrated the ability of high-intensity focused ultrasound (HIFU) to extracorporeally induce selective tissue destruction in the liver without causing damage to the intervening abdominal wall. The potential usefulness of HIFU as a noninvasive therapy for liver cancer has been suggested. This study observes sonographic and computed tomography (CT) characteristics of HIFU-ablated liver tissue in an attempt to assess the possibility of using these imaging methods to monitor the therapeutic results.

METHODS

A sonoablated lesion was induced in the liver in each of 20 rabbits with a HIFU therapeutic system. Sequential imaging of the hepatic sonolesions with sonography and CT was performed up to 8 days after treatment, and the imaging patterns were correlated with the histopathology.

RESULTS

Hepatic sonoablated tissue could be clearly visualized by sonography as a hypoechoic lesion. On contrast-enhanced CT, the sonolesions were depicted as nonenhanced low-density regions. There was good correlation among the sizes of sonography- and CT-depicted lesions and pathologic specimens.

CONCLUSION

In this model, sonography and contrast-enhanced CT were useful imaging modalities for monitoring sonolesion evolution after HIFU treatment.

Changes of hepatoma echo patterns with tumor growth. A study of the microanatomic basis in a rat model

OBJECTIVES

The echo patterns of human hepatoma vary considerably as the tumors grow. This sonographic study investigates the microanatomic basis of the echo-pattern changes in an animal model.

METHODS

ACI rats (n = 35) with intrahepatically implanted Morris hepatoma 3924A were imaged with 10-MHz ultrasound from days 7 to 28 after tumor implantation. The sonograms were precisely correlated with the histologic sections and microangiograms obtained from the same section plane.

RESULTS

Small hepatomas (size = 6.6 +/- 1.6 mm) without necrosis demonstrated a low-echo pattern. Medium-sized tumors (size = 11.7 +/- 3.3 mm) had a low-echo periphery and a high-echo center. The low-echo periphery corresponded to viable tumor and the high-echo core corresponded to central coagulation necrosis. Large tumors (size = 20.9 +/- 7.5 mm) with extensive necrosis revealed an irregular mixed-echo pattern.

CONCLUSIONS

The trend of increasing echogenicity of the hepatomas with tumor growth is due to the progression of coagulation necrosis.

Prospective study of magnetic resonance imaging and SPECT bone scans in renal allograft recipients: evidence for a self-limited subclinical abnormality of the hip

We recently reported that typical abnormalities of avascular necrosis (AVN) in magnetic resonance images (MRI) of the hips of asymptomatic renal transplant recipients whose plain radiographs are normal may improve spontaneously and even disappear completely. We present the results of serial bone scans, most of which were performed with single-photon emission computed tomography obtained over periods as long as 24 mo after transplantation in 72 of these patients. Three paired imaging studies (i.e., MR and bone scan performed within 30 days of each other) were available for each of these patients. In three patients, both the MR images and the bone scans showed changes consistent with bilateral AVN within 4 mo after transplantation. All three patients developed hip pain which was bilateral in two and unilateral in one. Two patients (three hips) required surgical intervention at which time AVN was found on pathologic examination of all three hips. None of the remaining 69 patients developed hip pain during the study. However, in nine patients whose MR studies were consistently normal, at least one bone scan was abnormal (13 hips). The presence of AVN was pathologically confirmed in each of the hips subjected to surgery. Where the imaging findings were identical to those in the asymptomatic patients as well as those in whom the imaging abnormality regressed, we suggest that the subclinical imaging abnormalities represent mild AVN, which is reversible in some cases. Since the process was identified in 10 hips by MRI and in 13 hips by bone scan, both studies are needed to detect subclinical AVN. This may be important if treatment of subclinical disease is clearly shown to prevent progression to symptomatic AVN.

Electrocautery of the tract after needle biopsy of the liver to reduce blood loss. Experience in the canine model

RATIONALE AND OBJECTIVES

Bleeding is the most common complication of needle biopsy of the liver. This study was designed to assess the feasibility of using unipolar electrocautery to decrease bleeding.

METHODS

Under general anesthesia, the livers of eight dogs were surgically exposed. A mean of 15 biopsies was obtained with 18-gauge needles from each liver by alternating biopsies without and with electrocautery. Cautery was performed by applying radiofrequency energy at 25 watts (6 animals) or 125 watts (2 animals) to the needle as the needle was withdrawn from the liver. Blood loss was measured by applying preweighed sponges to the biopsy site, then reweighing them after use. Biopsy specimens were examined by light microscopy.

RESULTS

The mean (+/- SD) blood loss was 0.44 g (+/- 1.36 g) with electrocautery and 1.47 g (+/- 2.23 g) without electrocautery (P < .01). No thermal injury was noted in the biopsy specimens when cautery was applied at 25 watts.

CONCLUSIONS

The application of radiofrequency current to the biopsy needle after liver biopsy is a feasible and effective method to reduce blood loss in our canine model.

Liver cancer ablation with extracorporeal high-intensity focused ultrasound

Recent animal studies have demonstrated the capacity of high-intensity focused ultrasound (HIFU) to extracorporeally ablate selective tissue targets in the liver without requiring surgical exposure of the liver or insertion of instruments into the liver. The potential value of HIFU as a noninvasive local treatment for human hepatic cancers has attracted considerable interest. This report reviews the current status of HIFU research and sets forth questions for future study.