Edge-enhanced spatiotemporal constrained reconstruction of undersampled dynamic contrast-enhanced radial MRI.

Dynamic contrast-enhanced magnetic resonance imaging (MRI) is a technique used to study and track contrast kinetics in an area of interest in the body over time. Reconstruction of images with high contrast and sharp edges from undersampled data is a challenge. While good results have been reported using a radial acquisition and a spatiotemporal constrained reconstruction (STCR) method, we propose improvements from using spatially adaptive weighting and an additional edge-based constraint. The new method uses intensity gradients from a sliding window reference image to improve the sharpness of edges in the reconstructed image. The method was tested on eight radial cardiac perfusion data sets with 24 rays and compared to the STCR method. The reconstructions showed that the new method, termed edge-enhanced spatiotemporal constrained reconstruction, was able to reconstruct images with sharper edges, and there were a 36%±13.7% increase in contrast-to-noise ratio and a 24%±11% increase in contrast near the edges when compared to STCR. The novelty of this paper is the combination of spatially adaptive weighting for spatial total variation (TV) constraint along with a gradient matching term to improve the sharpness of edges. The edge map from a reference image allows the reconstruction to trade-off between TV and edge enhancement, depending on the spatially varying weighting provided by the edge map.

Dual-energy, standard and low-kVp contrast-enhanced CT-cholangiography: a comparative analysis of image quality and radiation exposure.

OBJECTIVE: Quantitative image quality assessment in terms of image noise (IN), contrast-to-noise ratio (CNR), and signal-to-noise ratio (SNR) in relation to required radiation dose (RD) for dual-energy (DE), standard and low-kVp contrast-enhanced computed-tomography (CT) cholangiography. MATERIALS AND METHODS: For each of 22 DECT-cholangiography examinations, 3 image datasets were analyzed as independent single-source CT-acquisitions at different tube potential, i.e. 80 kVp, 120 kVp-equivalent (linear blended dataset M0.3: 30% 80 kVp, 70% 140 kVp), and 140 kVp. Analysis comprised determination of IN, CNR and SNR in regions of interest (ROI) placed in liver parenchyma and contrasted bile ducts. IN was evaluated as mean standard deviation of 3 ROI placed within liver parenchyma (segments 6/7, 5/8, 2/3); CNR was assessed as bile duct-to-liver parenchyma ratio, and SNR as bile duct-to-image noise ratio. RD in terms of CT dose index (CTDI(vol)), dose-length product (DLP) and effective dose (ED) has been determined for each of the datasets, and compared to console prediction and scan summary values. Using phantom measurements of CTDI(vol), a method for separating comprehensive RD values of DE-acquisitions into the original RD contribution of each tube (80 kVp/140 kVp) has been developed, enabling comparison of all 3 datasets as if independently acquired using single-source "single-energy" technique. RESULTS: Highest IN was detected for 80 kVp- (38.6 ± 5.1HU), lowest for 120 kVp-equivalent linear blended M0.3-datasets (23.1 ± 3.4HU) with significant differences between all datasets (P<0.001). Highest SNR and CNR were measured for M0.3- (SNR: 14.8 ± 4.1; CNR: 11.6 ± 3.8) and 80 kVp-datasets (SNR: 13.8 ± 4.8; CNR: 11.2 ± 4.5); lowest for 140 kVp-datasets (SNR: 9.5 ± 2.5; CNR: 7.1 ± 2.3) with significant differences between M0.3- and 140 kVp-datasets as well as between 80 kVp- and 140 kVp-datasets (both P<0.001 for both CNR, SNR). CTDI(vol), DLP and ED were reduced by 50% for low-kilovoltage acquisitions (CTDI(vol): 5.5 ± 1.4 mGy; DLP: 127.8 ± 40.1 mGy cm; ED: 1.9 ± 0.6 mSv) compared to comprehensive DE-acquisitions (CTDI(vol): 11.0 ± 2.3 mGy; DLP: 253.8 ± 67.5 mGy cm; ED: 3.8 ± 1.0 mSv, tube contribution: 80 kVp: 44.5%; 140 kVp: 55.5%), and by 20% compared to conventional acquisitions at 120 kVp (CTDI(vol): 6.71 mGy; DLP: 153.5 ± 16.9 mGy cm; ED: 2.3 ± 0.3 mSv). CONCLUSIONS: Despite higher IN, low-kilovoltage CT-cholangiography reveals no significant difference with respect to CNR and SNR when compared to linear blended images yielded by DECT. Compared to DECT or conventional CT at 120 kVp, contrast-enhanced low-kVp CT cholangiography potentially allows reduction of patient dose by up to 50% or 20%, respectively. Therefore, CT-cholangiography at 80 kVp should be considered as an alternative to DECT-cholangiography whenever DECT is unavailable, or if increased image quality of DECT regarding quantitative bile duct evaluation is not needed for diagnosis.

Iodine removal in intravenous dual-energy CT-cholangiography: is virtual non-enhanced imaging effective to replace true non-enhanced imaging?

PURPOSE: To evaluate whether virtual non-enhanced imaging (VNI) is effective to replace true non-enhanced imaging (TNI) applying iodine removal in intravenous dual-energy CT-cholangiography. MATERIALS AND METHODS: From April 2009 until February 2010, fifteen potential donors for living-related liver transplantation (mean age 37.6±10.8 years) were included. Potential donors underwent a two-phase CT-examination of the liver. The first phase consisted of a single-energy non-enhanced CT-acquisition that provided TNI. After administration of hepatobiliary contrast agent, the second phase was performed as a dual-energy cholangiographic CT-acquisition. This provided VNI. Objective image quality (attenuation values [bile ducts and liver parenchyma] and contrast-to-noise ratio) and subjective overall image quality (1 - excellent; 5 - non diagnostic) were evaluated. Effective radiation dose was compared. RESULTS: For TNI and VNI, attenuation values for bile ducts were 16.8±11.2HU and 5.5±17.0HU (p<0.05) and for liver parenchyma 55.3±8.4HU and 58.1±10.6HU (n.s.). For TNI and VNI, contrast-to-noise ratio was 2.6±0.6HU and 6.9±2.1HU (p<0.001). For VNI, subjective overall image quality was 1 in ten datasets, 2 in four datasets and 3 in one dataset. Effective radiation dose for the dual-energy cholangiographic CT-acquisition was 3.6±0.9mSv and for two-phase single-energy CT-cholangiography 5.1±1.3mSv (p<0.001). CONCLUSION: In this study on iodine removal in intravenous dual-energy CT-cholangiography, subjective image quality is equivalent, contrast-to-noise ratio is improved and effective radiation dose is reduced when VNI is performed. The differences between TNI and VNI with respect to attenuation values seem to have limited clinical relevance and therefore we consider VNI as effective to replace TNI.

Intravenous 64-multi-detector row CT-cholangiography of porcine livers: a feasibility study with definition of the temporal window for optimal bile duct delineation.

BACKGROUND/PURPOSE: To assess the feasibility of intravenous 64-multi-detector row computed tomography (CT)-cholangiography of porcine livers with definition of the temporal window for optimal bile duct delineation. METHODS: Six healthy Landrace pigs, each weighing 28.97 +/- 2.99 kg, underwent 64-multi-detector row CT-cholangiography. Each pig was infused with 50 ml of meglumine iotroxate continuously over a period of 20 min and, starting with the initiation of the infusion, 18 consecutive CT scans of the abdomen at 2-min intervals were acquired. All series were evaluated for bile duct visualization scores and maximum bile duct diameters as primary study goals and bile duct attenuation and liver enhancement as secondary study goals. RESULTS: Of the 16 analyzed biliary tract segments, maximum bile duct visualization scores ranged between 4.00 +/- 0.00 and 2.83 +/- 1.47. Time to maximum bile duct visualization scores ranged between 10 and 34 min. Average bile duct visualization scores for the 10- to 34-min interval ranged between 3.99 +/- 0.05 and 2.78 +/- 0.10. Maximum bile duct diameters ranged between 6.47 +/- 1.05 and 2.65 +/- 2.23 mm. Time to maximum bile duct diameters ranged between 24 and 34 min. Average bile duct diameters for the 10- to 34-min interval ranged between 6.00 +/- 0.38 and 2.40 +/- 0.13 mm. CONCLUSIONS: Intravenous 64-multi-detector row CT-cholangiography of non-diseased porcine liver is feasible, with the best bile duct delineation acquired between 10 and 34 min after initiation of the contrast agent infusion.

Cystic artery bleeding due to blunt gallbladder injury: computed tomography findings and treatment with transcatheter arterial embolization.

Blunt gallbladder injury is rare, and bleeding from the cystic artery due to blunt trauma is even rarer. We report herein a case of extraluminal bleeding of the gallbladder in a patient following blunt abdominal trauma. Contrast-enhanced computed tomography revealed pericholecystic fluid and extravasation of contrast material in the subcapsular liver space adjacent to the gallbladder. Abdominal digital subtraction angiography revealed pseudoaneurysm originating from a branch of the cystic artery. Successful treatment was achieved using selective transcatheter embolization, and cholecystectomy was not required.

Cholecystocolonic fistula diagnosed with CT-intravenous cholangiography.

Cholecystoenteric fistulas are often not diagnosed preoperatively and delineation of fistula can have an influence on surgical planning. We report a case of cholecystocolonic fistula diagnosed preoperatively using CT-i.v. cholangiography and review the published reports.

Spiral computed tomography-intravenous cholangiography with three-dimensional reconstructions for imaging the biliary tree.

This study aimed to assess the ability of CT-i.v. cholangiography to show the perihilar biliary and cystic duct anatomy and to assess the relative performance of axial, maximum intensity projection and surface rendered displays. We also assessed the correlation between serum bilirubin levels and adequacy of biliary opacification. Spiral CT was carried out following infusion of 100 mL of Biliscopin in 181 patients with suspected biliary disease. The display of biliary anatomy was of high quality, with 91% of patients having good opacification of at least first-order bile ducts and 84% having good opacification of at least third-order right and left hepatic ducts. The quality of biliary opacification correlated inversely to serum bilirubin levels, with levels above two to three times the normal value being associated with lower rates of good opacification. Maximum intensity projection and surface rendered reformats aided anatomical interpretation to a similar degree. The relative frequency of types of perihilar branching patterns and cystic duct junctional anatomy correlated closely to those reported from previous anatomical studies.

Volume rendering of three-dimensional drip infusion CT cholangiography in patients with suspected obstructive biliary disease: a retrospective study.

The purpose of this study was to evaluate the diagnostic potential of prolonged drip infusion CT cholangiography (DIC-CT) using meglumine iotroxate (Biliscopin) and 3D volume rendering in patients with suspected obstructive biliary disease. From a material of 142 patients who had undergone a drip infusion CT, all cases with a verified surgical or endoscopic retrograde cholangiography (ERC) diagnosis (n=33) were selected. Age-matched controls were selected from the remaining examinations. Three radiologists reviewed all 66 examinations in retrospect, independently as well as in consensus. The image quality and the estimated diagnostic quality were rated as good or moderate in 91% of the 198 reviews. The consensus sensitivity and specificity for diagnosing biliary stones was 88% and 94%, respectively (with sensitivities ranging from 88% to 94% for individual observers, and specificities from 86% to 96%). Two out of three strictures were observed. No false positive strictures were described. The use of volume rendering technique (VRT) improved diagnostic certainty in 28/198 (14%) of the evaluations. The visualization of ductal stones was improved in 18/48 (38%). No differences in diagnostic quality between single and multislice CT were observed. We conclude that a detailed image of the biliary tree with good sensitivity and specificity can be obtained by means of bilirubin-governed infusion time DIC-CT with volume rendering reconstruction.

The value of drip infusion cholangiography using multidetector-row helical CT in patients with choledocholithiasis.

The purposes of this study were to investigate the feasibility of drip infusion cholangiography computed tomography (CTCh) for choledocholithiasis and to compare the detection of the stone on CTCh with that of MR cholangiopancreatography (MRCP). CTCh examinations were performed after infusion of intravenous biliary contrast material (iotroxic acid meglumine, 100 ml) for patients with suspected biliary diseases and were reconstructed to maximum intensity projection (MIP) and multiplanar reformation (MPR). Of 432 patients who underwent CTCh, we identified 15 who underwent surgery or cholangioscopic removal for choledocholithiasis and 32 patients who underwent cholecystectomy due to cholecystolithiasis. Their MRCP images were compared with the CTCh images. The sensitivity and specificity of CTCh for detecting choledochal stones were 87% and 96% whereas those of MRCP were 80% and 88%. The sensitivity and specificity of CTCh for detecting gallstones were 78% and 100% whereas those of MRCP were 94% and 88%. CTCh allowed high sensitivity and specificity for detecting choledochal stones but diminished the detection for cholecystolithiasis compared with MRCP.

Stability of doxorubicin combined with Radioselectan, a contrast agent, for chemoembolization.

OBJECTIVE: To assess the stability of doxorubicin combined with Radioselectan. METHODS: Solutions of doxorubicin 5 mg/mL were prepared from commercially available 50 mg powder with 10 mL of Radioselectan. They were stored in glass syringes at 4, 25 and 45 degrees C. The concentrations of doxorubicin were determined using a stability-indicating high-performance liquid chromatography method. The initial and final pHs of solutions were compared. The times (t90) needed for doxorubicin to fall to 90% of its initial concentration were calculated by a linear regression analysis. RESULTS: The t90 [95% confidence limits] were 79 [75-83], 56 [53-59] and 22 [21-23] hours for the solutions stored at 4, 25 and 40 degrees C respectively. The initial pH of the solutions stored at 4, 25 and 40 degrees C were 6.52, 6.50 and 6.51 respectively. The final pH of solutions stored at 25 and 40 degrees C decreased significantly by 0.3 and 0.9 respectively. No change of pH solution stored at 4 degrees C was observed. CONCLUSION: Doxorubicin combined with Radioselectan stored at room temperature is stable for 48 h.

Accuracy of computed tomographic intravenous cholangiography (CT-IVC) with iotroxate in the detection of choledocholithiasis.

To determine the accuracy of computed tomographic intravenous cholangiography (CT-IVC) for detection of choledocholithiasis. Sixty-five patients undergoing endoscopic retrograde cholangiography (ERC) underwent CT-IVC prior to ERC, using a single detector helical CT following intravenous infusion of 100 ml iotroxate. Patients with bilirubin levels >3 times normal were excluded. ERC was indeterminate in three patients (4.7%) and CT-IVC in four (6.3%). Twenty-three patients had ductal calculi at ERC, and CT-IVC was positive in 22, with two false positives and one false negative: sensitivity 95.6%, specificity 94.3%. Stones were multiple in nine and solitary in 14. Of the 14 solitary stones, ten were

Distributing pattern of the bile duct of the caudate lobe on computed tomography with drip infusion cholangiography and its surgical significance.

BACKGROUND/AIMS: It is important to recognize the distribution of the bile ducts in the caudate lobe of the liver for the hepato-biliary surgery. To map the spatial relationship between the bile ducts and the liver parenchyma under physiological conditions, we performed an anatomical analysis of them using computed tomography combined with drip infusion cholangiography (DIC-CT). METHODOLOGY: We identified the bile ducts in the caudate lobe, which was divided into the Spiegel lobe, paracaval portion, and caudate process, with DIC-CT. We then investigated their number and confluence pattern in 132 patients without any abnormality in the hilar bile ducts. RESULTS: The mean number of the bile ducts in the caudate lobe was 2.68 per liver. In the Spiegel lobe, the branches drained into the left hepatic duct system in about 83%. The confluence of the paracaval branch was the left hepatic duct, right hepatic duct, and posterior segmental branch, all with the same frequency of approximately 30%. Almost all of the caudate process branches (92.4%) drained into the posterior segmental branch. CONCLUSIONS: DIC-CT is a useful method for the anatomical analysis of the intrahepatic bile ducts under physiological conditions, and we obtained novel and important findings for surgery.

Virtual CT cholangiography in patients with choledocholithiasis.

BACKGROUND: We evaluated the feasibility and accuracy of virtual computed tomographic cholangiography (VCTC) in detecting choledocholithiasis and imaging anatomic variations of the biliary tree. METHODS: Thirty-three consecutive patients with clinical and biological signs of choledocholithiasis underwent spiral CT after intravenous infusion of iotroxindimeglumine. Patients with total serum bilirubin levels above 3 mg/dL were not included in this study. Spiral data sets were used to construct intralumenal images of the biliary tree. The images were reviewed by two abdominal radiologists. The biliary ducts were divided into three segments, so the analysis was based on 99 segments. The diagnosis obtained by VCTC was compared with the final diagnosis established by endoscopic retrograde cholangiography or intraoperative cholangiography. RESULTS: VCTC correctly depicted biliary stones in nine of 10 patients and anatomic variations in all five patients, and no false-positive cases were observed. VCTC showed excellent endolumenal visualization of 87 of 99 segments of the biliary tree. The processing time (9.3 +/- 2.1 min) was particularly short. CONCLUSION: VCTC with intravenous infusion of iotroxindimeglumine may be a feasible clinical tool, with acceptable accuracy in selected cases.

Thallium-201 accumulation in a patient with brain abscess.

A 57-year-old man was admitted to our hospital because of high fever and generalized tonic seizure. Brain magnetic resonance imaging (MRI) delineated multiple abnormal intensity areas. Thallium-201 (201Tl) scintigraphy revealed abnormal uptake in the brain. The imaging findings did not allow definitive exclusion of brain tumor, even though brain abscess was the more strongly suspected diagnosis. As the patient improved, the multiple abnormal intensity areas in the brain on MRI and the abnormal areas of accumulation on 201Tl scintigraphy were reduced, and eventually completely disappeared. A final diagnosis of brain abscess was therefore made. Since relatively few studies have reported 201Tl accumulation in cases of brain abscess, we report here our patient in whom the changes in the accumulation of 201Tl in a brain abscess were observed over time.

Multi-slice three-dimensional spiral CT cholangiography: a new technique for diagnosis of biliary diseases.

OBJECTIVE: To validate multi-slice three-dimensional spiral CT cholangiography (3-D CTC) in clinical diagnosis of biliary diseases. METHODS: This study included 146 patients with biliary diseases, involving 73 cases of biliary tumor, 87 cases of radioparent calculus, 12 cases of post cholangio-jejunostomy and one case of congenital choledochocyst. The data of thin-slice volumetric CT scan were sent to the workstation (GE Advantage Windows 3.1). Rational 3-D CTC including maximum intensity projection, minimum intensity projection, surface shaded display, CT virtual endoscopy and ray sumption was performed. The diagnostic accuracy of 3-D CTC was compared with that of conventional CT, ultrasonography and endoscopic retrograde cholangiopancreaticography (ERCP). RESULTS: Different biliary diseases showed distinct imaging manifestations on 3-D CTC. As a new technique for assessing the status of post cholangio-jejunostomy, 3-D CTC was superior to conventional CT, ultrasonography and ERCP in diagnosis of negative biliary calculus, extrahepatic cholangiocarcinoma, cancer embolus of the biliary duct, carcinoma of the pancreas head and periampullar carcinoma. It was also superior to conventional CT, ultrasonography or equal to ERCP in diagnosis of hilar cholangiocarcinoma, but inferior to conventional CT and ultrasonography in diagnosis of gallbladder cancer. CONCLUSION: 3-D CTC as a non-invasive and sensitive technique for the diagnosis of biliary diseases with high diagnostic accuracy will greatly increase the detection rate of biliary diseases.

Usefulness of three-dimensional CT cholangiography for patients prior to laparoscopic cholecystectomy.

PURPOSE: The aim of this study was to demonstrate three-dimensional biliary anatomy by using spiral CT scanning for patients prior to laparoscopic cholecystectomy. MATERIALS AND METHODS: We studied 22 patients (11 men, 11 women; mean age, 60 years) with preoperative imaging. All patients had normal serum bilirubin levels. Either 50 ml (in 10 cases) or 100 ml (in 12 cases) of meglumine iotroxate was infused intravenously over 30 minutes. Spiral CT scanning was started immediately after the infusion was finished. Volumetric data through the entire biliary tracts were obtained during one breath-hold. The data were reconstructed by using a maximum intensity projection algorithm and three-dimensional shaded surface rendering. RESULTS: In all patients, the anatomical relationship between the cystic duct and the common bile duct was clearly depicted, including one with junctional anomaly. The intrahepatic biliary ducts and the confluence of the hepatic ducts were displayed from all angles. The third or higher intrahepatic branches were delineated in 11 of the 12 (92%) patients with the use of 100 ml of the cholangiographic agent and in seven of the 10 (70%) with 50 ml. CONCLUSION: Three-dimensional CT cholangiography was able to provide adequate information about precise biliary anatomy.

Helical CT cholangiography for the detection and localization of bile duct leakage.

OBJECTIVE: We describe the use of helical CT cholangiography or helical CT after administration of biliary i.v. contrast material to verify and localize bile duct leakage. CONCLUSION: Helical CT cholangiography revealed bile leaks in seven patients after penetrating trauma or liver or gallbladder surgery and excluded bile leaks in two patients with blunt liver trauma. Endoscopic retrograde cholangiography was performed in only one of seven patients with bile leakage and was avoided in an additional two patients in whom CT cholangiography excluded leakage. The method is a feasible, noninvasive tool for the detection and localization of bile leaks and may help avoid endoscopic retrograde cholangiography.

MR and CT cholangiography in evaluation of the biliary tract.

OBJECTIVE: To compare MR and CT cholangiography (MRC and CTC) in evaluating the anatomy of the extrahepatic biliary tract and the pathology related to the gallbladder. MATERIAL AND METHODS: Twenty-three patients underwent MRC and CTC with a biliary contrast medium for investigation of biliary disease. 3D displays of both were also obtained. Endoscopic retrograde cholangiography was performed in 17 patients, and the pathology of all 23 was evaluated. RESULTS: Overall, the image quality was higher with CTC than with MRC (4.7 vs 3.9, p < 0.05). The cystic duct was demonstrated better by CTC than MRC (p < 0.05). Multiplanar reformation (MPR) and source images provided additional information to that obtained from 3D MRC and CTC images. Gallstones were revealed in 6 patients by CTC and in 5 of these 6 by MRC. In 2 patients with cholecystitis, CTC demonstrated gallbladder wall thickening but MRC did not. In 3 patients with adenomyomatosis. MRC demonstrated Rokitansky-Aschoff sinuses (RAS) while CTC demonstrated focal gallbladder wall thickening in all 3 and RAS in 1 of them. CONCLUSION: Both MRC and CTC provided anatomical and pathological information about the biliary system. With both techniques, however, either MPR or source images proved necessary in addition for evaluating the biliary system anatomy and pathology. The gallbladder wall was depicted clearly in source CTC, but MRC is recommended for the evaluation of adenomyomatosis because it depicts RAS clearly.