Optimization of parameters for the detection of cerebral aneurysms: CT angiography of a model

PURPOSE: To optimize parameters with computed tomographic angiography for the detection of cerebral aneurysms. MATERIALS AND METHODS: Model aneurysms were placed randomly at various branch points and scanned multiple times with spiral technique. The final analysis included 63 branch points and 22 aneurysms. Each spiral scan used a different parameter combination. Collimation ranged from 1.5 to 4.0 mm and pitch ranged from 1:1 to 1.5:1. Images were constructed with shaded surface display (SSD) and maximum intensity projection (MIP) algorithms and were interpreted by three readers for the presence or absence of aneurysm. RESULTS: The receiver operating characteristic (ROC) curve area for 1.5-mm collimation was greater than those of 3- or 4-mm collimation (P < .01 and P < .001, respectively). There was no statistically significant difference in the ROC curve areas between 3- and 4-mm collimation (P = .37). There was no statistically significant decrease in ROC curve area when increasing pitch from 1:1 to 1.5:1 for any value of collimation (P = .96). For all parameter combinations the ROC curve areas for SSD images was greater than that of MIP images (P < .0001). CONCLUSION: For cerebral aneurysm detection, narrow collimation is superior to wider collimation. Mild increases in pitch do not substantially degrade diagnostic accuracy. SSD offers improved diagnostic accuracy over MIP display in this model.     

Computed tomographic angiography for the evaluation of carotid artery stenosis

BACKGROUND AND PURPOSE: No previous study has compared the reliability of carotid artery measurement provided by axial images, shaded surface display (SSD), and maximum intensity projection (MIP). METHODS: Helical CT and conventional angiography were performed prospectively in 20 patients with atherosclerotic stenosis of the internal carotid artery. Stenosis measurement was performed in a blinded fashion on angiography and CT by two independent examiners. Calcifications were segmented when they were located far enough from the vascular lumen. SSD and MIP were systematically performed for each carotid bifurcation. We measured stenosis using conventional angiography as standard and the different CT reconstructions (axial images, SSD, and MIP) by comparing the stenosis diameter at its narrowest point to the normal internal carotid artery. The degree of stenosis was classified into six groups: no stenosis, mild stenosis (< 30%), moderate stenosis (30% to 70%), severe stenosis (> 70%), near occlusion, and occlusion (100%). No measurement was made in cases of normal artery, near occlusion, and occlusion. RESULTS: Correlations between angiography and the three types of reconstruction were very good. Axial sections correctly classified the carotid arteries in 95% of cases. In 10 carotid arteries, stenosis was not assessable by SSD and MIP because of calcifications. In the remaining carotid arteries, MIP correctly classified the degree of stenosis in 96% of cases, whereas SSD misclassified 21% of cases. CONCLUSIONS: Our study showed that axial images provide a reliable evaluation of carotid artery stenosis. Calcifications are limiting factors in SSD or MIP. When atherosclerotic plaques are not calcified, MIP reconstructions provide a more reliable measurement of the vascular lumen than SSD.     

Cryosurgical ablation of hepatic tumors

BACKGROUND: Cryosurgical ablation of hepatic tumors relies on nonspecific tissue necrosis due to freezing as well as microvascular thrombosis. Patients with selected primary and metastatic hepatic malignancies who are not candidates for surgical resection are afforded potentially curative benefit using this technique. METHODS: Forty patients underwent cryosurgery for hepatic malignancy related to colorectal metastasis (n = 27), hepatocellular carcinoma (n = 8), metastatic breast (n = 2), metastatic neuroendocrine (n = 2), and metastatic ovarian carcinoma (n = 1). Intraoperative ultrasound (IOUS) was used in all patients to help locate the tumor and guide the cryosurgical trocar to the lesions. RESULTS: Indications for cryosurgical ablation included bilobar and centrally located disease, poor medical risk, insufficient hepatic reserve, and involved margin after wedge resection. Major complications included hepatic parenchyma cracking requiring transfusion in 5 patients, 1 postoperative biliary stenosis, and 1 inferior vena cava injury. There were 3 postoperative deaths from non-hepatic-related events. Based on Kaplan-Meier analysis the estimated overall survival for patients with hepatocellular carcinoma (60% at 18 months) was compared with patients with colorectal metastases (30% at 18 months). Nine patients (23%) are currently free of disease with an average follow-up of 17.7 months. The pattern of failure was identified at the site of cryosurgical ablation in 2 of 88 lesions. CONCLUSIONS: Cryosurgical ablation of selected hepatic malignancies is a safe and viable treatment for patients not amenable to surgical resection.     

Synchronized oscillations in the visual cortex--a synergetic model

We evaluated the image quality of three-dimensional (3D) spiral CT using a Somatom Plus CT scanner (Siemens, Germany). A T-shaped acrylate plastic model was made and scanning was performed with a table speed of 5 mm/sec for 24 seconds. The thickness of the X-ray beam was 5mm with one second per rotation. The various images of the model were created based on the shaded surface display (SSD) method and the effect of threshold and rotation (spin and tilt) on the quality of the 3D images was studied. The increase of threshold caused a rapid decrease in the diameter of the stick observed on the film, and this phenomenon was particularly remarkable on the transverse stick and the junctional portion of the longitudinal stick. The change of spin or tilt did not affect the diameter of the stick on the film. It was found that the depth perception of the stick could be achieved with the gray scale technique. We concluded that the interpretation of the 3D spiral CT image obtained with SSD needs caution and the diagnosis should not be made only on this image.     

Studies on utility of MR T2-weighted images using multishot echo-planar imaging for hepatic mass lesions

MR T2-weighted images using multishot echo-planar imaging (EPI) and fast spin-echo (FSE) sequences were obtained in 22 patients with hepatic masses. Multishot EPI sequences included eight-shot breath-hold EPI and 16-shot EPI without breath-hold, while FSE sequences included nonfat-suppressed respiratory-triggered FSE, fat-suppressed respiratory-triggered FSE, and nonfat-suppressed breath-hold FSE. Signal-to-noise ratio, contrast-to-noise ratio and artifacts were compared between EPI and FSE images of 47 hepatic masses. In evaluating solid tumors, EPI provided image quality equal or superior to that of FSE, whereas in the evaluation of nonsolid tumors FSE showed better image quality than EPI. In conclusion, it was demonstrated that in the evaluation of hepatic solid tumors T2-weighted eight-shot breath-hold EPI can replace both nonfat-suppressed respiratory-triggered FSE and breath-hold FSE, and it was suggested that eight-shot breath-hold EPI can replace fat-suppressed respiratory-triggered FSE to reduce patient discomfort and increase examination throughput.     

Diagnostic impact of four postprocessing techniques in evaluating contrast-enhanced three-dimensional MR angiography

OBJECTIVE: The purpose of this study was to determine the added diagnostic value of various three-dimensional (3D) data viewing techniques when analyzing contrast-enhanced 3D MR angiography. MATERIALS AND METHODS: Twenty patients (mean age, 62 years) with symptomatic peripheral vascular disease were assessed with breath-hold, contrast-enhanced 3D MR angiography and catheter angiography, which served as the standard of reference. After an initial interpretation of the 3D MR angiographic data sets based only on standardized maximum intensity projections (MIP), the diagnostic gain of the stepwise addition of interactive multiplanar reformations, shaded-surface displays (SSD), and virtual intraarterial endoscopy (VIE) images was calculated. Time required for each step of postprocessing was measured. RESULTS: Pathologic changes were revealed by catheter angiography in 60 vascular segments (50 severe stenoses, seven aneurysms, and three occlusions). The average postprocessing times were MIP, 8 min (range, 5-12 min); multiplanar reformations, 9 min (range, 3-11 min); SSD, 15 min (range, 8-25 min); and VIE, 40 min (range, 18-63 min). Addition of multiplanar reformations to MIPs resulted in the greatest gain of diagnostic accuracy, from 92% to 96%, and diagnostic confidence. When analysis was based on all four techniques, receiver operating characteristic curve analysis revealed only minimal improvements in diagnostic confidence, whereas diagnostic accuracy remained unchanged at 96%. CONCLUSION: Accurate and time-effective analysis of contrast-enhanced 3D MR angiography should be based on MIP algorithms and multiplanar reformations. Additional evaluation with VIE or SSD techniques is time-consuming and provides little diagnostic gain.     

Hepatic lesions: discrimination of nonsolid, benign lesions from solid, malignant lesions with heavily T2-weighted fast spin-echo MR imaging

PURPOSE: To determine whether the combined use of heavily and moderately T2-weighted fast spin-echo magnetic resonance (MR) images improves differentiation of non-solid, benign hepatic lesions from solid malignancies. MATERIALS AND METHODS: Three radiologists reviewed moderately (n = 133) and heavily (n = 133) T2-weighted and multiphasic dynamic contrast material-enhanced (n = 93) MR images in 133 patients with proved focal hepatic lesions (95 benign, 38 malignant). The radiologists used a five-point scale to rate their confidence in determination of malignancy. RESULTS: All three reviewers were statistically significantly better able to differentiate small (diameter less than 3 cm; n = 84) benignancies from small malignancies with the combination of moderately and heavily T2-weighted images (area under the receiver operating characteristic curve, 0.99 for each reader) than with moderately T2-weighted images alone (area, 0.88-0.90; P < .05). Confident diagnoses were rendered in 69 (82%) patients, with 100% accuracy for the combined use of moderately and heavily T2-weighted images. For larger lesions (diameter 3 cm or larger; n = 49), accurate differentiation was possible with moderately T2-weighted images alone. Additional use of multiphasic images did not improve the sensitivity, specificity, or accuracy of image interpretation. CONCLUSION: The combined use of moderately and heavily T2-weighted fast spin-echo MR images improves differentiation of small benign hepatic lesions from small malignant lesions.     

A new prenylated flavone from Artocarpus champeden inhibits the K(+)-dependent amino acid transport in Bombyx mori midgut

OBJECTIVE: The purpose of our study was to assess the frequency and imaging characteristics of nonpathologic portal perfusion defects in subcapsular liver parenchyma adjacent to the right ribs as seen on CT hepatic arteriography combined with helical CT during arterial portography (CTAP). MATERIALS AND METHODS: From January 1994 to June 1997, helical CTAP and CT hepatic arteriography were performed in 94 patients with suspected malignant hepatic tumors. The patient group comprised 66 men and 28 women ranging from 37 to 83 years old (mean, 64 years old). Three radiologists retrospectively reviewed the images obtained by CTAP to evaluate portal perfusion defects adjacent to the right ribs for location, shape, size, and correlation with findings seen on CT hepatic arteriography. RESULTS: We identified 16 nonpathologic portal perfusion defects adjacent to the right eighth (n = 1), ninth (n = 12), and tenth (n = 3) ribs in 12 (13%) of 94 patients. The shapes of the 16 defects were circular (n = 1), oval (n = 7), wedge (n = 3), and irregular (n = 5). The defects were 10-30 mm in diameter (mean, 16.9 mm). In four (25%) of 16 locations, CT hepatic arteriography showed poorly identified, homogeneous, irregularly shaped areas of contrast enhancement corresponding to the defects seen on CTAP. The portal perfusion defects were proven to be nonpathologic on definitive surgery in four patients and on follow-up radiography in eight patients. CONCLUSION: Helical CTAP may show nonpathologic portal perfusion defects adjacent to the right ribs. Most defects did not appear circular but rather were oval, irregular, or wedge-shaped. CT hepatic arteriography infrequently showed corresponding findings. Radiologists should recognize this potential pitfall when interpreting images obtained by helical CTAP.     

Use of maximum intensity projections in CT angiography: a basic review

Maximum intensity projection (MIP) is a simple three-dimensional visualization tool that can be used to display computed tomographic angiography data sets. MIP images are not threshold dependent and preserve attenuation information. Thus, they often yield acceptable results even in cases in which shaded surface display images fail because of threshold problems. MIP is particularly useful for depicting small vessels. Because MIP does not allow for differentiation between foreground and background, MIP images are best suited for displaying relatively simple anatomic situations in which superimposition of structures does not occur (eg, the abdominal aorta). If anatomic structures are superimposed over the vessel of interest, the MIP technique can provide images of diagnostic quality as long as the contrast of the vessel of interest is sufficiently high compared with that of surrounding structures. Editing procedures for MIP are usually used to exclude unwanted structures from the volume of interest and include cutting functions and region-growing algorithms. Artifacts from vessel pulsation and respiratory motion may occur and simulate abnormalities, but, with careful attention, they can be distinguished from real disease. MIP images should always be interpreted together with the original transaxial data set. Knowledge of display properties and artifacts is necessary for correct interpretation of MIP images and helps one create images of optimal quality, choose appropriate examination parameters, and distinguish artifacts from disease.     

Spiral computer tomography in diagnosis of hepatic diseases]

Spiral computer tomography (SCT) is a new method of computer tomography by which, in contrast to conventional CT, the information about absorptional capacity of tissues is obtained without omission of images which makes it possible to build MPR and 3D of a very high quality. 205 patients with diseases of hepatopancreatoduodenal area were examined, in 189 patients the diagnosis being verified. Optimal technique of intravenous bolus contrasting in SCT was developed. Using various time interval between the start of the scanning and the beginning of infusion of contrast media, it is possible to obtain primary image of the arteries (arterial phase of contrasting, time of delay 18-25 sec.), the picture of veins and the image of saturation of hepatic parenchyma--(venous return phase, time of delay 60-80 sec.), to reveal characteristics of contrasting of the liver masses during delay (8-15 min) phase. The largest quantity of masses are revealed in arterial phase of contrasting. Specific features of contrasting in hemangiomas and malignant tumors of the liver has been revealed. Hemangiomas absorb contrast medium already at the early phase as hypercontrasted lacunas in an outlying areas, at a late phase they are hyperdenced in relation to hepatic parenchyma. Primary and metastatic tumors of the liver accumulate contrast medium in an early phase along the whole area and quickly lose contrast medium during parenchymal phase. The method of contrast intensification enables evaluation of interrelation between tumor and vessels, to determine passage of hepatic arteries and branches of portal and hepatic veins, to visualise choledochal duct, to determine the distance between hepatic and tumor surface, and to produce these data as a view of multiplanar and three-dimensional image (reconstruction). The effectiveness of obtained reconstructions in planning of the extent of surgical intervention is demonstrated.     

Dynamic MR imaging of liver tumors: analysis with temporal reconstruction images

PURPOSE: To graphically display the time dependency of contrast enhancement of liver tumors at examination with dynamic magnetic resonance (MR) imaging. MATERIALS AND METHODS: A temporal reconstruction image was generated by obtaining a line of interest drawn on a single image through the liver and the tumor and reformatted over a sequence of temporal images. This calculated image expressed the temporal evolution of the line, including nontumoral liver and tumor, with regard to three variables: signal intensity, enhancement, and velocity. This allowed a visually integrated analysis of 95 hepatic lesions studied with dynamic single-section MR imaging after contrast material administration. RESULTS: Temporal reconstruction images were obtained for all the dynamic studies. Five patterns of enhancement based on signal intensity and velocity variations coupled with morphologic information were found: wall, diffusion, moderate enhancement, marked progressive, and early intense patterns. CONCLUSION: Temporal reconstruction of liver tumors after contrast material administration can be used to analyze, describe, and report the dynamics of lesion enhancement with morphologic and temporal resolution.     

Retinoic acid receptor expression abnormalities in lung cancer: important clues or major obstacles?

We have developed a cine display of postprocessed 3D MR images of the thoracic aorta. Maximum intensity projection (MIP) images of the thoracic aorta in each phase were reconstructed from consecutive 2D-cine MR data sets, and displayed in a cine loop. The postprocessed 3D MR images clearly showed the relationship between major cervical branches and aortic pathologies such as aneurysms, and cine display presented the flow pattern in the aorta. 3D-cine MR angiography seems to be useful for follow-up studies of thoracic aortic diseases especially in patients with renal dysfunction.     

Methotrexate hepatotoxicity: what is the evidence?

PURPOSE: To assess the usefulness of fractal geometry in quantitatively evaluating the convergence of peripheral vessels on peripheral lung tumors in maximum intensity projection (MIP) images. MATERIALS AND METHODS: We studied the MIP images of 34 pathologically proved small peripheral lung tumors (lung cancer in 21, hamartoma in 13) in 34 patients. To obtain MIP images, spiral CT (SOMATOM PLUS; Siemens) was performed during a single breath hold (24-second scan time, 2-mm section thickness, and 2 mm/sec table feed time, reconstructed at 1-mm increments). To evaluate the convergence of the peripheral vessels and bronchi towards the tumor, we fixed a region of interest (ROI) on the hilar side of the lung tumor, parallel to the chest wall, which consisted of 64 x 64 square pixels, in the images that divided at the center of the window width. We counted the overlapping pixels by the two-dimensional box-counting method and obtained fractal dimensional data on lung cancers and hamartomas. RESULTS: There was a statistically significant difference in the fractal dimension (D) between lung cancers (D = 1.81 +/- 0.13) and hamartomas (D = 1.67 +/- 0.10) (P = 0.0067). CONCLUSION: Fractal geometry could be useful in the diagnosis of small peripheral lung tumors.     

"Reversed' illusion with three-dimensional Müller-Lyer shapes

The purpose of this study was to determine whether the Müller-Lyer illusion is produced by a mechanism which uses information defined in the retinal coordinates, or by a mechanism taking into account the three-dimensional (3-D) shape of the illusion figure. The classical Müller-Lyer figure could not be used to address this question since it is two-dimensional. Three-dimensional Müller-Lyer figures were created to see if the illusion they produce is correlated with the shape of the projected retinal image, or with the shape of these figures defined in a 3-D coordinate frame. In the experiments retinal image shape was juxtaposed against the 3-D shape of the illusion displays. For some displays the direction in which the fins pointed, relative to the shafts, in the 3-D frame was the "opposite" of the direction in which they pointed in the retinal images. For such displays, the illusion predicted on the basis of the 3-D structure was the opposite of that predicted on the basis of retinal image shapes. For another 3-D display the fins were oriented such that each projected a single straight line in the retinal image, thus the typical retinal image (< >, > <) was replaced by straight lines (symbol: see text). For all the displays the observed illusion was consistent with how the fins were oriented relative to the shaft in the 3-D coordinate frame, ie with the 3-D shape of the illusion displays. The retinal image shape appeared to play little, if any, role. One conclusion that emerges is that the specific retinal image shape projected by the classical line-drawn pattern is neither necessary nor sufficient for producing the illusion. The present findings are inconsistent with two well known theories of the Müller-Lyer illusion: inappropriate constancy scaling and selective filtering.     

Satisfaction of the "Mister Employee": a goal to be reached]

Six patients with pulmonary emphysema scheduled to undergo thoracoscopic lung volume reduction surgery (TLVRS) were evaluated by three-dimensional (3-D) dynamic pulmonary xenon-133 SPECT. Serial 30-second dynamic SPECT data for equilibrium and washout (for 5 min) were acquired using a continuous repetitive rotating acquisition mode with a triple-detector SPECT system. SPECT data were reconstructed to 3-D images with a color, surface-rendering technique, and a 3-D fusion image of the 3-min washout image over the equilibrium image was obtained. Regional ventilation was visually assessed on the fusion 3-D images and quantified by xenon-133 half-washout time (T1/2) and mean transit time (MTT). The 3-D fusion image localized and lateralized the worst diseased sites with xenon-133 retention. Xenon-133 retention, T1/2 and MTT were reduced on these images in five patients with improved pulmonary function tests following TLVRS. However, xenon-133 retention was greater in one with asynchronous diaphragm movement after TLVRS. This modality will assist TLVRS in determining the lung resection target and in evaluating the treatment effect.     

Changes of hepatic volume after successful Kasai operation

The number of long term survivors who have undergone Kasai operation for biliary atresia is increasing, but some have a hepatic dysfunction likely to require liver transplantation in the near future. Hepatic volume possibly reflects whole liver function, and our objective was to assess the changes of hepatic volume after Kasai operation. Ten patients were studied. Ages ranged from 3 to 27 years. They underwent Kasai operation at ages ranging from 50 to 80 days. Liver areas (cm2) on CT images were measured with an image processing and analysis program (NIH Image 1.57). Hepatic volume (cm3) was calculated by summing up the areas of each image and multiplying by slice thickness (cm). After Kasai operation, the size of the liver increased to 1.7-1.9 times the standard volume, and then reduced to normal size around 5 years of age. In the teens, hepatic volume decreased below the standard volume. Segmental hypertrophy accompanying atrophy of other hepatic segments was observed in 9 out of 10 patients; right lobe hypertrophy: 6, medial segment: 2, and lateral segment: 1. Therefore, progressive hepatic atrophy begins in the teens, but is compensated for by segmental hypertrophy.     

Evaluation of benign vs malignant hepatic lesions with positron emission tomography

BACKGROUND: In most malignant cells, the relatively low level of glucose-6-phosphatase leads to accumulation and trapping of [18F]fluorodeoxyglucose (FDG) intracellularly, allowing the visualization of increased uptake compared with normal cells. OBJECTIVES: To assess the value of FDG positron emission tomography (PET) to differentiate benign from malignant hepatic lesions and to determine in which types of hepatic tumors PET can help evaluate stage, monitor response to therapy, and detect recurrence. DESIGN: Prospective blinded-comparison clinical cohort study. SETTING: Tertiary care university hospital and clinic. PATIENTS: One hundred ten consecutive referred patients with hepatic lesions 1 cm or larger on screening computed tomographic (CT) images who were seen for evaluation and potential resection underwent PET imaging. There were 60 men and 50 women with a mean (+/-SD) age of 59 +/- 14 years. Follow-up was 100%. INTERVENTIONS: A PET scan using static imaging was performed on all patients. The PET scan imaging and biopsy, surgery, or both were performed, providing pathological samples within 2 months of PET imaging. All PET images were correlated with CT scan to localize the lesion. However, PET investigators were unaware of any previous interpretation of the CT scan. MAIN OUTCOME MEASURES: Visual interpretation, lesion-to-normal liver background (L/B) ratio of radioactivity, and standard uptake value (SUV) were correlated with pathological diagnosis. RESULTS: All (100%) liver metastases from adenocarcinoma and sarcoma primaries in 66 patients and all cholangiocarcinomas in 8 patients had increased uptake values, L/B ratios greater than 2, and an SUV greater than 3.5. Hepatocellular carcinoma had increased FDG uptake in 16 of 23 patients and poor uptake in 7 patients. All benign hepatic lesions (n = 23), including adenoma and fibronodular hyperplasia, had poor uptake, an L/B ratio of less than 2, and an SUV less than 3.5, except for 1 of 3 abscesses that had definite uptake. CONCLUSIONS: The PET technique using FDG static imaging was useful to differentiate malignant from benign lesions in the liver. Limitations include false-positive results in a minority of abscesses and false-negative results in a minority of hepatocellular carcinoma. The PET technique was useful in tumor staging and detection of recurrence, as well as monitoring response to therapy for all adenocarcinomas and sarcomas and most hepatocellular carcinomas. Therefore, pretherapy PET imaging is recommended to help assess new hepatic lesions.     

Intraoperative radiotherapy for pancreatic carcinoma with hepatic or peritoneal metastases

BACKGROUND/AIMS: The purpose of this study was to determine the efficacy of intraoperative radiotherapy (IORT) for unresectable pancreatic carcinoma associated with hepatic or peritoneal metastasis. METHODOLOGY: Between 1991 and 1994, 53 patients with pancreatic carcinoma associated with hepatic or peritoneal metastasis underwent surgery. Twenty-four of these patients received IORT, while 29 received no radiation therapy. The efficacy of IORT on the postoperative survival and pain relief for these patients was retrospectively analyzed. RESULTS: Postoperative survival was lowest in the subgroup of patients (n = 18) with both hepatic and peritoneal metastases, and this group did not benefit from IORT (IORT, n = 6; no IORT, n = 12) in terms of survival. Similarly, there was no significant difference in the survival rates between patients undergoing IORT (n = 10) and patients without IORT (n = 11) in the subgroup of patients with hepatic metastasis but without peritoneal metastasis. However, patients with peritoneal metastasis but without hepatic metastasis benefited significantly from IORT (IORT, n = 8; no IORT, n = 6) (p < 0.05). Pain relief following IORT was observed in 9 out of 10 patients who had experienced pain prior to surgery. CONCLUSION: Pancreatic carcinoma associated with peritoneal metastasis but without hepatic metastasis can be palliated by IORT. In addition, pain palliation in patients who require gastrointestinal or biliary drainage can also be achieved by IORT.     

Hepatic peribiliary cysts: multiple tiny cysts within the larger portal tract, hepatic hilum, or both

PURPOSE: To describe characteristic imaging features of hepatic peribiliary cysts. MATERIALS AND METHODS: Four patients with hepatic cysts in which the radiologic (n = 3) or histologic (n = 1) findings were consistent with peribiliary cysts of the liver (multiple small cysts seen exclusively in the larger portal tract, hepatic hilum, or both at gross examination and dilatations of extramural peribiliary gland at histologic examination) underwent computed tomography (CT) and ultrasound (US). In three patients, CT was performed after drip infusion of cholangiographic contrast material. RESULTS: Contrast material-enhanced CT clearly depicted many tiny cysts along the larger portal veins up to the third- or fourth-order branch (n = 3). US depicted multiple cysts in the echogenic portal tract definitely (n = 2) or equivocally (n = 2). On cholangiographic contrast-enhanced CT scans, cystic areas were located adjacent to or surrounding the bile ducts, and the possibility of biliary dilatation, communication, or both was disproved. CONCLUSION: Hepatic peribiliary cysts can be diagnosed with US and enhanced CT, especially with CT performed after administration of cholangiographic contrast material.