Fatal myocardial infarction investigated using contrast-enhanced postmortem computed tomography: A case report.

Conventional autopsies are considered standard methods for clarifying cause of death. However, because of the increasing use of computed tomography, magnetic resonance imaging, and other diagnostic imaging techniques, autopsy imaging is now more frequently adopted to identify diseases with unknown causes and sudden deaths. A 84-year-old man was diagnosed with acute myocardial infarction using coronary angiography. After taking oral antiplatelet medication in the catheterization laboratory, the patient suddenly coughed violently, lost consciousness, and was diagnosed with cardiac arrest. Spontaneous circulation did not return after 50 min of cardiopulmonary resuscitation. To elucidate the cause of the cardiac arrest, we performed contrast-enhanced postmortem computed tomography (PMCT), which revealed cardiac tamponade due to cardiac rupture of the inferior myocardium. Our findings reaffirm the effectiveness of contrast-enhanced PMCT in the diagnosis of sudden death in the clinical setting.

Diffusion-weighted MR imaging of non-complicated hepatic cysts: Value of 3T computed diffusion-weighted imaging.

PURPOSE: To investigate the utility of computed 3T diffusion-weighted imaging (c-DWI) for the diagnosis of non-complicated hepatic cysts with a focus on the T2 shine-through effect. MATERIALS AND METHODS: In 50 patients with non-complicated hepatic cysts we acquired one set of DWIs (b-value 0 and 1000 s/mm(2)) at 1.5T, and two sets at 3T (b-value 0 and 1000 s/mm(2), TE 70 ms; b-value 0 and 600 s/mm(2), TE 60 ms). We defined the original DWIs acquired with b = 1000 s/mm(2) at 1.5T and 3T as "o-1.5T-1000" and "o-3T-1000". c-DWIs were calculated with 3T DWI at b-values of 0 and 600 s/mm(2). c-DWI with b = 1000 and 1500 s/mm(2) were defined as "c-1000" and "c-1500". Radiologists evaluated the signal intensity (SI) of the cysts using a 3-point score where 1 = not visible, 2 = discernible, and 3 = clearly visible. They calculated the contrast ratio (CR) between the cysts and the surrounding liver parenchyma on each DWIs and recorded the apparent diffusion coefficient (ADC) with a b-value = 0 and 1000 s/mm(2) on 1.5T- and 3T DWIs. RESULTS: Compared with o-1.5T-1000 DWI, the visual scores of all but the c-1500 DWIs were higher (p = 0.07 for c-1500- and p < 0.01 for the other DWIs). The CR at b = 1000 s/mm(2) was higher on o-3T-1000- than on o-1.5T-1000- (p < 0.01) but not higher than on c-1500 DWIs (p = 0.96). The CR at b = 0 s/mm(2) on 3T images with TE 70 ms was higher than on 1.5T images (p < 0.01). The ADC value was higher for 3T- than 1.5T images (p < 0.01). CONCLUSIONS: Non-complicated hepatic cysts showed higher SI on o-3T-1000- than o-1.5T-1000 DWIs due to the T2-shine through effect. This high SI was suppressed on c-1500 DWIs.

Iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) magnetic resonance imaging as a biomarker for symptomatic multiple myeloma.

INTRODUCTION: To evaluate the effectiveness of iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) magnetic resonance imaging (MRI) to discriminate between symptomatic and asymptomatic myeloma in lumbar bone marrow without visible focal lesions. MATERIALS AND METHODS: The lumbar spine was examined with 3-T MRI in 11 patients with asymptomatic myeloma and 24 patients with symptomatic myeloma. The fat-signal fraction was calculated from the ratio of the signal intensity in the fat image divided by the signal intensity of the corresponding ROI in the in-phase IDEAL image. The t test was used to compare the asymptomatic and symptomatic groups. ROC curves were constructed to determine the ability of variables to discriminate between symptomatic and asymptomatic myeloma. RESULTS: Univariate analysis showed that ß2-microglobulin and bone marrow plasma cell percent (BMPC%) were significantly higher and fat-signal fraction was significantly lower with symptomatic myeloma than with asymptomatic myeloma. Areas under the curve were 0.847 for ß2;-microglobulin, 0.834 for fat-signal fraction, and 0.759 for BMPC%. CONCLUSION: The fat-signal fraction as a biomarker for multiple myeloma enables discrimination of symptomatic myeloma from asymptomatic myeloma. The fat-signal fraction offers superior sensitivity and specificity to BMPC% of biopsy specimens.

A new technique for noise reduction at coronary CT angiography with multi-phase data-averaging and non-rigid image registration.

OBJECTIVES: To investigate the feasibility of a newly developed noise reduction technique at coronary CT angiography (CTA) that uses multi-phase data-averaging and non-rigid image registration. METHODS: Sixty-five patients underwent coronary CTA with prospective ECG-triggering. The range of the phase window was set at 70-80% of the R-R interval. First, three sets of consecutive volume data at 70%, 75% and 80% of the R-R interval were prepared. Second, we applied non-rigid registration to align the 70% and 80% images to the 75% image. Finally, we performed weighted averaging of the three images and generated a de-noised image. The image noise and contrast-to-noise ratio (CNR) in the proximal coronary arteries between the conventional 75% and the de-noised images were compared. Two radiologists evaluated the image quality using a 5-point scale (1, poor; 5, excellent). RESULTS: On de-noised images, mean image noise was significantly lower than on conventional 75% images (18.3 HU ± 2.6 vs. 23.0 HU ± 3.3, P < 0.01) and the CNR was significantly higher (P < 0.01). The mean image quality score for conventional 75% and de-noised images was 3.9 and 4.4, respectively (P < 0.01). CONCLUSIONS: Our method reduces image noise and improves image quality at coronary CTA. KEY POINTS: • We introduce a new method for image noise reduction at cardiac CT. • Multiple data acquisitions of an object and their averaging yield lower noise. • Our method uses multi-phase images reconstructed from unused redundant imaging data. • It reduces image noise by averaging multi-phase images transformed by non-rigid registration. • This method achieves a 20% image noise reduction at cardiac CT.

Multidetector computed tomography-based microstructural analysis reveals reduced bone mineral content and trabecular bone changes in the lumbar spine after transarterial chemoembolization therapy for hepatocellular carcinoma.

PURPOSE: It is well recognized that therapeutic irradiation can result in bone damage. However, long-term bone toxicity associated with computed tomography (CT) performed during interventional angiography has received little attention. The purpose of this study was to determine the prevalence of osteoporosis and trabecular microstructural changes in patients after transarterial chemoembolization (TACE) for hepatocellular carcinoma therapy using an interventional-CT system. MATERIALS AND METHODS: Spinal microarchitecture was examined by 64-detector CT in 81 patients who underwent TACE, 35 patients with chronic hepatitis, and 79 controls. For each patient, the volumetric CT dose index (CTDIv) during TACE (CTDIv (TACE)), the dose-length product (DLP) during TACE (DLP (TACE)), and CTDIv and DLP of routine dynamic CT scans (CTDIv (CT) and DLP (CT), respectively), were calculated as the sum since 2008. Using a three dimensional (3D) image analysis system, the tissue bone mineral density (tBMD) and trabecular parameters of the 12th thoracic vertebra were calculated. Using tBMD at a reported cutoff value of 68 mg/cm3, the prevalence of osteoporosis was assessed. RESULTS: The prevalence of osteoporosis was significantly greater in the TACE vs. the control group (39.6% vs. 18.2% for males, P<0.05 and 60.6% vs. 34.8% for females, P<0.01). Multivariate regression analysis demonstrated that sex, age, and CTDIv (CT) significantly affected the risk of osteoporosis. Of these indices, CTDIv (CT) had the highest area under the curve (AUC) (0.735). Correlation analyses of tBMD with cumulative radiation dose revealed weak correlations between tBMD and CTDIv (CT) (r2 = 0.194, P<0.001). CONCLUSION: The prevalence of osteoporosis was significantly higher in post TACE patients than in control subjects. The cumulative radiation dose related to routine dynamic CT studies was a significant contributor to the prevalence of osteoporosis.

A longitudinal computed tomography study of lenalidomide and bortezomib treatment for multiple myeloma: trabecular microarchitecture and biomechanics assessed using multidetector computed tomography.

BACKGROUND: Bone disease is a common feature in patients with multiple myeloma. In this study, we investigated whether lenalidomide, similar to bortezomib, affects the microarchitecture and biomechanics of bones using clinical CT-based FEM. MATERIALS AND METHODS: Bone lesions were evaluated using whole-body 64-section multidetector CT scan. For microstructural- and CT/FEM analyses, the volume of interest was defined as a 10-mm thickness of the central part of the L3 vertebral body. Microstructural parameters and mechanical properties were calculated using a 3-D image analysis system. The changes from baseline to the second examination within groups were calculated. Relationships between baseline disease characteristics and percent changes of trabecular parameters were assessed using Spearman correlation analysis. RESULTS: Thirty-two patients were treated with bortezomib and 18 patients were treated with lenalidomide. At the second CT scan, apparent trabecular number, failure load, and stiffness were decreased in the bortezomib group and failure load and stiffness were increased significantly in the lenalidomide group. In the lenalidomide group, response to chemotherapy was positively associated with increases in failure load (ρ = 0.57; P < .05) and stiffness (ρ = 0.50; P < .05). CONCLUSION: Lenalidomide treatment resulted in significant increases in CT/FEM-derived estimates of bone strength. Response to chemotherapy predicted lenalidomide-induced bone changes and good responders had increased bone strength.

Re-evaluation of detectability of liver metastases by contrast-enhanced CT: added value of hepatic arterial phase imaging.

PURPOSE: We compared the detectability of liver metastases on 2- and 3-phase images using robust statistical methods. Nine radiologists evaluated unenhanced CT plus portal venous phase (2-phase) images and 2-phase plus hepatic arterial phase (HAP) (3-phase) images. MATERIALS AND METHODS: Our study included 54 patients with primary malignant tumors who underwent 3-phase hepatic dynamic CT more than twice to screen for liver metastases; 24 had 1-6 liver metastases measuring 4-27 mm in diameter (median 13 mm). The other 30 had no metastases. Nine board-certified radiologists participated in our observer performance study. They specified the location of the metastatic lesions and rated the probability of metastatic nodules on 2-phase images acquired with and without HAP imaging. We used jackknife alternative free-response receiver operating characteristic (JAFROC) analysis to compare their performances. RESULTS: For all radiologists the area under the curve without and with HAP imaging was 0.86 and 0.88, respectively; the difference was significant (p = 0.04). For metastases smaller than 10 mm the averaged lesion localization fraction without and with HAP imaging was 0.17 and 0.26 (p < 0.01). CONCLUSION: Adding HAP to 2-phase imaging improved the detectability of liver metastases, especially of lesions smaller than 10 mm.

Magnetic resonance evaluation of multiple myeloma at 3.0 Tesla: how do bone marrow plasma cell percentage and selection of protocols affect lesion conspicuity?

PURPOSE: To compare various pulse sequences in terms of percent contrast and contrast-to-noise ratio (CNR) for detection of focal multiple myeloma lesions and to assess the dependence of lesion conspicuity on the bone marrow plasma cell percent (BMPC%). MATERIALS AND METHODS: Sagittal T1-weighted FSE, fat-suppressed T2-weighted FSE (FS- T2 FSE), fast STIR and iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) imaging of the lumbar spine were performed (n = 45). Bone marrow (BM)-focal myeloma lesion percent contrast and CNR were calculated. Spearman rank correlation coefficients were obtained between percent contrast, CNR and BMPC%. Percent contrasts and CNRs were compared among the three imaging sequences. RESULTS: BM-focal lesion percent contrasts, CNRs and BMPC% showed significant negative correlations in the three fat-suppression techniques. Percent contrast and CNRs were significantly higher for FS- T2 FSE than for STIR (P<0.01, P<0.05, respectively), but no significant differences were found among the three fat-suppression methods in the low tumor load BM group. CONCLUSION: The higher BMPC% was within BM, the less conspicuous the focal lesion was on fat-suppressed MRI. The most effective protocol for detecting focal lesions was FS- T2 FSE. In the high tumor load BM group, no significant differences in lesion conspicuity were identified among the three fat-suppression techniques.

Non-occlusive mesenteric ischemia (NOMI): utility of measuring the diameters of the superior mesenteric artery and superior mesenteric vein at multidetector CT.

OBJECTIVE: To investigate the diagnostic capability of multidetector computed tomography for detecting non-occlusive mesenteric ischemia (NOMI). METHODS: We studied 11 NOMI patients and 44 controls. Radiologists evaluated the CT images for the presence of bowel ischemia and measured the diameters of the superior mesenteric artery and the superior mesenteric vein (D SMA and D SMV). We also performed linear discriminant analysis (LDA) using D SMA and D SMV. RESULTS: All NOMI patients presented with more than 2 CT findings of bowel ischemia. D SMA and D SMV were significantly smaller in NOMI patients than in the controls (p < 0.01). At the optimal cut-off values for D SMA (6.5 mm), D SMV (9.0 mm), and the Z value in LDA (0.93), sensitivity and specificity were 81.8 and 81.8; 81.8 and 88.6; and 81.8 and 97.7 %, respectively. CONCLUSIONS: D SMA and D SMV were significantly smaller in NOMI patients than in the controls and D SMV is a more significant parameter than D SMA.

Effect of lapatinib on hepatic parenchymal enhancement on gadoxetate disodium (EOB)-enhanced MRI scans of the rat liver.

PURPOSE: The purpose of this study was to investigate the effect of lapatinib treatment on hepatic parenchymal enhancement on Gd-EOB-MRI scans in rat. MATERIALS AND METHODS: Institutional animal review board approval was received prior to the commencement of all studies. Five rats received a single oral dose of 100 mg/kg/day lapatinib for 7 consecutive days. The controls (n = 5) were given 0.5 % (w/v) aqueous hydroxypropyl methyl cellulose containing 0.1 % (v/v) Tween 80 for 7 days. After the acquisition of gadoxetate disodium-enhanced MR images using 0.025 mmol gadolinium/kg, their livers were subjected to pathologic study to determine the expression level of organic anion-transporting polypeptide 1 (oatp1) and multi-drug resistance-associated protein 2 (mrp2). RESULTS: Relative enhancement of the liver was similar in both groups. At the hepatobiliary phase, which in rats occurs 3 min after the injection of Gd-EOB, it was 0.90 ± 0.06 in lapatinib-treated rats and 0.84 ± 0.08 in the controls (p = 0.30). There was also no difference in the expression level of oatp1 and mrp2. CONCLUSION: In rats, the administration of lapatinib for 7 days had no effect on hepatic parenchymal enhancement on Gd-EOB-MRI scans.

Detectability of hepatocellular carcinoma by gadoxetate disodium-enhanced hepatic MRI: tumor-by-tumor analysis in explant livers.

PURPOSE: To investigate the detectability of hepatocellular carcinoma (HCC) on Gd-EOB-enhanced MR images (Gd-EOB-MRI), we performed tumor-by-tumor analysis of pathologically confirmed tumors using explants from cirrhotic patients who had undergone liver transplantation. MATERIALS AND METHODS: We studied 11 explanted livers and classified the tumor intensity during the arterial phase (AP) and the hepatobiliary phase (HBP) as low in HBP with early enhancement (EE) in AP (A), as high in HBP with EE in AP (B), as low in HBP without EE in AP (C), as high in HBP without EE in AP (D), and as iso-intense in HBP with EE in AP (E). The diagnostic criteria for HCC were (i) pattern A and C, (ii) pattern A and E, (iii) pattern C and E, and (iv) patterns A, C, and E. RESULTS: Of the 71 HCCs, 22 were not detected at MRI; of these, 9 were moderately differentiated and 13 were well-differentiated HCCs. The sensitivity of Gd-EOB-MRI for diagnostic criteria 1, 2, 3, and 4 was 63.4%, 52.1%, 22.5%, and 69.0%. CONCLUSION: The maximum sensitivity of Gd-EOB-MRI for HCC was only 69.0% even when diagnostic criteria that included all previously reported HCC patterns were adopted.

Direct vasodilation by transdermal administration of nitroglycerin: preliminary, randomized, placebo-controlled trial of nitroglycerin skin spray for premedication before artery puncture.

PURPOSE: Transdermal administration of nitroglycerin (NTG) before arterial puncture may improve puncture success. The objective of this study was to evaluate the vasodilation effect of NTG skin spray on brachial arteries. MATERIALS AND METHODS: We recruited 10 healthy volunteers. On different days and in random order we sprayed their skin above the right or left brachial artery with a solution containing 0.3 mg NTG or above the right brachial artery with physiological saline. A radiologist ultrasonographically measured the cross-sectional area of right brachial artery before and at 5-min intervals for up to 25 min after spraying and calculated the rate of increase of the area. RESULTS: The average vasodilation rate after spraying with NTG above the right brachial arteries of 10 volunteers was 16.4% at 5 min, 23.6% at 10 min, 19.6% at 15 min, and 16.5% at 20 min; spraying with NTG above the left brachial artery or with physiological saline alone elicited few changes. The vasodilation rate 10 min after spraying with NTG above the right brachial artery was significantly higher than for control groups (P < 0.001). CONCLUSIONS: Transdermal application of NTG spray dilated the targeted brachial artery. This technique may be a good premedication before artery puncture.

Effect of age on the fractional anisotropy (FA) value of peripheral nerves and clinical significance of the age-corrected FA value for evaluating polyneuropathies.

INTRODUCTION: We investigated the correlation between age and the fractional anisotropy (FA) values of peripheral nerves in healthy adults and compared the age-corrected FA values of peripheral nerves in healthy subjects and patients with polyneuropathy. METHODS: The institutional review board approved this study and informed consent was obtained from all participants before entry into the study. We optimized diffusion tensor imaging using a 3-T magnetic resonance scanner and an extremity coil for scanning tibial nerves. The effect of age and sex on the FA values of tibial nerves in healthy volunteers was investigated and the age-corrected FA values of tibial nerves in healthy volunteers and patients with polyneuropathy were compared. RESULTS: The maximum FA values of the tibial nerves remained constant until age 45 (approximately 0.516); they subsequently decreased by 0.004/year in healthy volunteers. After removing the effect of age with an age-adjusted equation, the median maximum FA values in the volunteers and patients were 0.518 (range, 0.406-0.616) and 0.442 (range, 0.376-0.530), respectively. The age-corrected FA values were significantly lower in the patients than the healthy volunteers (p < 0.001). There was no significant gender-related difference in the maximum FA values of the tibial nerves (p = 0.416). CONCLUSION: The age-corrected FA value of the peripheral nerves helps to differentiate between age-related peripheral nerve degeneration and polyneuropathies.

Migration to the pulmonary artery of nine metallic coils placed in the internal iliac vein for treatment of giant rectal varices.

Transcatheter venous embolization with metallic coils is a safe and reliable method for the treatment of pelvic congestion syndrome and pelvic varicocele. While rare, coil migration to the pulmonary arteries is potentially fatal. We report the migration to the pulmonary artery of a cluster of nine metallic microcoils placed in the internal iliac vein to obliterate giant rectal varices. Our patient suffered no severe sequelae. To avoid coil migration to the pulmonary arteries, the coils chosen for placement must take into consideration the characteristics of the target vessels, particularly of larger veins.

Iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) imaging of multiple myeloma: initial clinical efficiency results.

OBJECTIVES: To evaluate the effectiveness of the iterative decomposition of water and fat with echo asymmetric and least-squares estimation (IDEAL) MRI to quantify tumour infiltration into the lumbar vertebrae in myeloma patients without visible focal lesions. METHODS: The lumbar spine was examined with 3 T MRI in 24 patients with multiple myeloma and in 26 controls. The fat-signal fraction was calculated as the mean value from three vertebral bodies. A post hoc test was used to compare the fat-signal fraction in controls and patients with monoclonal gammopathy of undetermined significance (MGUS), asymptomatic myeloma or symptomatic myeloma. Differences were considered significant at P < 0.05. The fat-signal fraction and ß(2)-microglobulin-to-albumin ratio were entered into the discriminant analysis. RESULTS: Fat-signal fractions were significantly lower in patients with symptomatic myelomas (43.9 ±19.7%, P < 0.01) than in the other three groups. Discriminant analysis showed that 22 of the 24 patients (92%) were correctly classified into symptomatic or non-symptomatic myeloma groups. CONCLUSIONS: Fat quantification using the IDEAL sequence in MRI was significantly different when comparing patients with symptomatic myeloma and those with asymptomatic myeloma. The fat-signal fraction and ß(2)-microglobulin-to-albumin ratio facilitated discrimination of symptomatic myeloma from non-symptomatic myeloma in patients without focal bone lesions. KEY POINTS: • A new magnetic resonance technique (IDEAL) offers new insights in multiple myeloma. • Fat-signal fractions were lower in patients with symptomatic myelomas than in those with asymptomatic myelomas. • The ß2-microglobulin-to-albumin ratio also aided discrimination of symptomatic myeloma. • The fat-signal fraction may provide information about the myeloma cell mass.

Clinical significance of the transitional phase at gadoxetate disodium-enhanced hepatic MRI for the diagnosis of hepatocellular carcinoma: preliminary results.

OBJECTIVES: To investigate the clinical significance of the "transitional phase" at gadoxetate disodium (Gd-EOB)-enhanced magnetic resonance imaging for diagnosing hepatocellular carcinoma (HCC). METHODS: We studied 54 patients with 70 histologically diagnosed HCC. Transitional- and hepatobiliary-phase (TP, HBP) images were acquired 3 and 20 minutes after Gd-EOB injection, respectively. Radiologists measured the size of the hepatic tumors on images and surgical specimens and qualitatively evaluated the signal intensity of the hepatic tumors during TP and HBP independently. RESULTS: In 4 patients with portal tumor embolism who had undergone percutaneous transhepatic portal embolization and who manifested arterioportal (AP) shunts, the low-intensity area was larger during HBP than TP. Of the 70 HCCs, 4 were of high signal intensity during HBP and 2 were of slightly low intensity during TP. CONCLUSION: Tumor extension seen during TP rather than HBP more accurately reflected histological findings in patients with HCC with portal tumor thrombi, percutaneous transhepatic portal embolization, or AP shunt.

Evaluation of lumber nerve root compression using thin-slice thickness coronal magnetic resonance imaging: three-dimensional fat-suppressed multi-shot balanced non-steady-state free precession versus three-dimensional T1-weighted spoiled gradient-recalled echo.

PURPOSE: The aim of this study was to compare the three-dimensional fat-suppressed balanced non-steady-state free precession (3D FS-nSSFP) sequence and the 3D T1-weighted spoiled gradient-recalled echo (3D T1-GRE) sequence for evaluating lumbar nerve root compression with continuous thin-slice coronal magnetic resonance (MR) images. MATERIALS AND METHODS: The institutional review board approved this study, and written informed consent was obtained from all 35 patients. We optimized continuous 2.5-mm thick lumbar coronal images with 3D FS-nSSFP and 3D T1-GRE. We calculated the contrast-to-noise ratio (CNR) for nerve roots and other structures on images with the two sequences. With knowledge of the final diagnosis, we assessed the visibility of nerve root compression on these images. RESULTS: The CNR values of nerve roots were significantly higher on images with 3D FS-nSSFP than on those with 3D T1-GRE. These continuous thin-slice coronal images facilitated visualization of nerve root compression in >91% of patients. There was no statistically significant difference between the two sequences in the detection of nerve root compression. CONCLUSION: Continuous thin-slice coronal MR images using 3D FS-nSSFP and 3D T1-GRE sequences are sufficient to evaluate lumbar nerve root compression, and 3D FS-nSSFP is superior to 3D T1-GRE for depiction of lumbar nerve roots.

Signal intensity of lanthanum carbonate on magnetic resonance images: phantom study.

PURPOSE: Lanthanum carbonate (LC) is used to treat hyperphosphatemia. The purpose of this study was to investigate the signal intensity (SI) of LC on magnetic resonance imaging (MRI) scans of phantoms. MATERIALS AND METHODS: LC tablets were thoroughly ground and mixed with distilled water or edible agar (0.05, 0.25, 0.5, and 2.5 mg/ml) in plastic bottles. Four intact tablets were placed in plastic bottles that did or did not contain distilled water or agar. Two radiologists consensually evaluated T1- and T2-weighted images (WIs) obtained with 1.5- and 3.0-T MRI systems for the SI of unground and ground tablets. RESULTS: On T1- and T2WI, the SIs of the LC suspensions and the solvents alone were similar; the SIs of unground tablets alone and of the air were also similar. Unground tablets in phantoms filled with solvent exhibited lower SI than the solvent. Ground tablets in suspension were not visualized on MRI or computed tomography. These results remained unchanged regardless of differences in magnetic field strength or the solvent used. CONCLUSION: Ground LC had no contrast enhancement effect on T1WI; on T2WI it did not affect the SI of the solvent. Unground LC tablets may be visualized as a "filling defect" on MRI.

Hepatocellular carcinoma in patients weighing 70 kg or less: initial trial of compact-bolus dynamic CT with low-dose contrast material at 80 kVp.

OBJECTIVE: The purpose of this study was to compare the diagnostic capability of hepatic dynamic CT with low-dose contrast material (420 mg I/kg body weight) at 80 kVp with that of the same modality performed with standard-dose contrast material at 120 kVp. SUBJECTS AND METHODS: We randomly assigned 111 patients (50 women, 61 men; mean age, 69.1 years) with known or suspected hepatocellular carcinoma and a body weight of 70 kg or less to one of two protocols. In the 80-kVp protocol, the contrast material (444 mg I/kg body weight) was delivered over 15 seconds at a tube voltage of 80 kVp. In the 120-kVp protocol, a contrast dose of 600 mg I/kg was delivered over 30 seconds at 120 kVp. Of the 111 patients, 38 had hypervascular hepatocellular carcinoma. Using the Mann-Whitney U test, we compared the two protocols for the contrast-to-noise ratio of the tumors (difference between tumor attenuation and liver attenuation divided by noise in the liver) and the figure of merit (square of contrast-to-noise ratio divided by effective dose) of the tumors during the arterial phase of imaging. Effective doses also were compared. RESULTS: The contrast-to-noise ratio of the tumors was significantly higher with the 80-kVp than with the 120-kVp protocol (median, 5.3 vs 4.2; p = 0.04). The figure of merit also was significantly higher with the 80-kVp than with the 120-kVp protocol (10.2 vs 5.3, p = 0.02). The effective dose was significantly lower with the 80-kVp than with the 120-kVp protocol (2.97 vs 3.41 mSv, p < 0.01). CONCLUSION: With 80-kVp acquisition, the contrast-to-noise ratio and figure of merit of tumors during the arterial phase improved despite the lower contrast dose and radiation exposure.

Effect of lapatinib on hepatic parenchymal enhancement on gadoxetate disodium (EOB)-enhanced MRI scans.

We present changes seen on hepatobiliary phase (HBP)-gadoxetate disodium (EOB)-enhanced magnetic resonance image of a woman with liver metastases who was treated with lapatinib. After treatment, the HBP images appeared like portal venous phase images. This suggests that lapatinib, an inhibitor of organic anion transporting polypeptide 1B1, one of the substrates of EOB, inhibits EOB uptake by hepatocytes. In patients treated with lapatinib, the ability to diagnose liver tumors on HBP images may be compromised.