Comparison of Four Diagnostic Guidelines for Hepatocellular Carcinoma Using Gadoxetic Acid-enhanced Liver MRI.

Background Noninvasive diagnostic guidelines for hepatocellular carcinoma (HCC) vary across different global geographic areas, especially regarding criteria about gadoxetic acid-enhanced MRI. Purpose To compare the diagnostic performance of four different international HCC diagnosis guidelines and readers' judgment in diagnosing HCC using gadoxetic acid-enhanced MRI in patients at high risk for HCC. Materials and Methods This retrospective study included patients who had not undergone treatment, were at risk for HCC, and who underwent gadoxetic acid-enhanced MRI from January 2015 to June 2018 from 11 tertiary hospitals in South Korea. Four radiologists independently reviewed focal liver lesions (FLLs) according to four guidelines: American Association for the Study of Liver Diseases (AASLD)/Liver Imaging Reporting and Data System (LI-RADS), Korean Liver Cancer Association-National Cancer Center (KLCA-NCC), European Association for the Study of the Liver (EASL), and Asian Pacific Association for the Study of the Liver (APASL). Reader judgment (HCC or not HCC) was also recorded. Malignant FLLs were confirmed at pathology, and histologic and clinical follow-up data were used for benign FLLs. The guidelines' diagnostic performance was compared using generalized estimating equations. Additionally, the diagnostic odds ratio was assessed. Results A total of 2445 FLLs (median size, 27.4 mm) were analyzed in 2237 patients (mean age, 59 years ± 11 [SD]; 1666 male patients); 69.3% (1694 of 2445) were HCCs. KLCA-NCC showed the highest accuracy (80.0%; 95% CI: 78.7, 81.2; P = .001), with high sensitivity in Eastern guidelines (APASL, 89.1% [95% CI: 87.8, 90.3]; KLCA-NCC, 78.2% [95% CI: 76.6, 79.7]) and high specificity in Western guidelines (AASLD/LI-RADS, 89.6% [95% CI: 87.8, 91.2]; EASL, 88.1% [95% CI: 86.2, 89.9]) (P = .001). The diagnostic odds ratios were 20.7 (95% CI: 17.0, 25.3) for AASLD/LI-RADS, 18.9 (95% CI: 15.8, 22.6) for KLCA-NCC, 16.8 (95% CI: 13.8, 20.4) for EASL, and 8.9 (95% CI: 7.4, 10.7) for APASL. The readers' judgment demonstrated higher accuracy than that of the guidelines (accuracy, 86.0%; 95% CI: 84.9, 86.9; P = .001). Conclusion Among four different international HCC diagnosis guidelines, Eastern guidelines demonstrated higher sensitivity, whereas Western guidelines displayed higher specificity. KLCA-NCC achieved the highest accuracy, and AASLD/LI-RADS exhibited the highest diagnostic odds ratio. © RSNA, 2024 Supplemental material is available for this article.

Corona enhancement can substitute enhancing capsule in the imaging diagnosis of small (≤ 3 cm) HCCs on gadoxetic acid-enhanced MRI.

OBJECTIVES: This study aimed to elucidate the relationship between gadoxetic acid-enhanced magnetic resonance imaging (MRI) features-enhancing capsule, corona enhancement or hypointense rim-observed in hepatocellular carcinomas (HCCs). METHODS: Of the HCCs surgically confirmed during a 5-year period (2013-2017), ≤ 3-cm lesions (n = 83) in 78 patients were evaluated. Presence of corona enhancement and enhancing capsule on multiphasic dynamic imaging and presence of hypointense rim on hepatobiliary phase imaging were determined retrospectively by two independent observers. The relationship among the three imaging features was statistically analysed and correlated with the presence of histologic fibrous capsules, tumour differentiation and gross morphologic type. RESULTS: There was substantial overall interobserver agreement in determining the presence of the three imaging features. Sixty (72.3%) lesions had histologic fibrous capsule positively correlated with all three imaging features (p < 0.05). Corona enhancement was the most common (66.3%) feature followed by enhancing capsule (61.4%) and hypointense rim (33.7%), and the correspondence rate of enhancing capsule to corona enhancement was 68.6% (p = 0.004). Corona enhancement was more frequently observed in moderately differentiated HCCs than other lesions (p = 0.012) and not dependent (p = 0.465) on the tumour size, while enhancing capsule was significantly dependent on tumour size, as indicated by univariate (p < 0.001) and multivariate analyses (odds ratio, 4.241; p = 0.002). CONCLUSIONS: Among the capsular features, corona enhancement might closely relate to enhancing capsule in HCCs. Corona enhancement was not dependent on tumour size and had the highest incidence of appearance on gadoxetic acid-enhanced multiphasic dynamic MRI. KEY POINTS: • Enhancing capsule has a limited role in the LI-RADS categorisation during gadoxetic acid-enhanced MRI. • Appearance of corona enhancement is closely related to enhancing capsule and is not dependent on size of HCCs. • Corona enhancement can substitute enhancing capsule in the diagnosis of HCCs during multiple arterial and portal venous phase gadoxetic acid-enhanced MRI.

Subtraction Images From Portal Venous Phase Gadoxetic Acid-Enhanced MRI for Observing Washout and Enhancing Capsule Features in LI-RADS Version 2018.

OBJECTIVE. The purpose of this study is to validate the use of subtraction images derived from gadoxetic acid-enhanced MRI for observation of washout and enhancing capsule in the diagnosis of hepatocellular carcinoma (HCC). MATERIALS AND METHODS. For 120 histologically verified HCCs in 115 high-risk patients, the presence of washout and enhancing capsule in the portal venous phase (PVP) on conventional MR images with and without corresponding subtraction images was determined by two independent observers. The incremental value of subtraction imaging in upgrading the categories outlined in the Liver Imaging Reporting and Data System (LI-RADS) version 2018 for the diagnosis of HCC was analyzed for different subgroups of patients classified on the basis of lesion size (< 10 mm, 10-19 mm, ≥ 20 mm), unenhanced T1-weighted signal intensity, and arterial phase hyperenhancement (APHE) of the lesions. RESULTS. When conventional PVP images were compared with the combination of conventional and subtraction PVP images, only T1-weighted isointensity or hyperintensity significantly increased the detection of washout (eight vs 15 of 18 lesions; p = 0.0233). Detection of enhancing capsule was significantly increased (p < 0.05) regardless of various factors, except for a lesion size of less than 2 cm (five vs nine of 36 lesions; p = 0.1336). Two lesions (one LI-RADS category 3 lesion and one LI-RADS category 4 lesion) with APHE were upgraded to category 5 on the basis of a review of PVP subtraction images. CONCLUSION. PVP subtraction imaging during gadoxetic acid-enhanced MRI can upgrade LI-RADS categories for the diagnosis of HCC because of its superior ability in depicting enhancing capsule and the incremental benefit of showing washout.

Texture Analysis of Hepatocellular Carcinoma on Magnetic Resonance Imaging: Assessment for Performance in Predicting Histopathologic Grade.

OBJECTIVE: The aim of the study was to evaluate the performance of texture analysis for discriminating the histopathological grade of hepatocellular carcinoma (HCC) on magnetic resonance imaging. METHODS: Preoperative magnetic resonance imaging data from 101 patients with HCC, including T2-weighted imaging, arterial phase, and apparent diffusion coefficient mapping, were analyzed using texture analysis software (TexRAD). Differences among the histological groups were analyzed using the Mann-Whitney U test. The performance of texture features was evaluated using receiver operating characteristic analysis. RESULTS: Entropy was the most significantly relevant texture feature for distinguishing each histological grade group of HCC (P < 0.05). In ROC analysis, entropy with spatial scale filter 3 (area under curve the receiver operating characteristic curve [AUC], 0.778), mean with coarse filter (spatial scale filter 5; AUC, 0.670), and skewness without filtration (AUC, 0.760) had the highest AUC value on T2-weighted imaging, arterial phase, and apparent diffusion coefficient maps, respectively. CONCLUSIONS: Magnetic resonance imaging texture analysis demonstrated potential for predicting the histopathological grade of HCCs.

Sclerotic changes of cavernous hemangioma in the cirrhotic liver: long-term follow-up using dynamic contrast-enhanced computed tomography.

PURPOSE: To determine the intra- and extralesional factors that predict sclerotic degeneration of hepatic hemangiomas in the cirrhotic liver on long-term follow-up computed tomography (CT) examinations. MATERIALS AND METHODS: Fifty-seven hepatic hemangiomas (> 5 mm in diameter) in 41 cirrhotic patients, recruited over a 5-year period (January 2005-December 2009), were subjected to CT to determine which factors predict sclerotic contraction or degeneration in hemangiomas. Prior and follow-up CT examinations (from 2000 to 2018) were included to observe time-related changes. The patients' gender, age, cause of cirrhosis, progression of background liver cirrhosis, lesion size/location/contrast enhancement pattern, and serum aspartate transaminase to platelet ratio index were correlated with sclerotic changes of each lesion. RESULTS: According to the dynamic CT features, 36 of 57 (63%) hemangiomas were determined to have sclerotic changes during the follow-up period (1.1-14.4 years, median: 7.8 years), including 28 lesions (49%) reduced by ≥ 20% in diameter. In univariate analysis, age (p = 0.047) and morphological progression of background cirrhosis (p = 0.013) were significantly related to sclerotic change of hemangiomas. In the logistic regression analysis, only morphological progression of background liver cirrhosis independently predicted sclerotic change (odds ratio: 4.88, p = 0.007). With the exception of exophytic location free from size reduction (p = 0.023 in multivariate analysis), no other analyzed factors were significantly correlated with sclerotic changes. CONCLUSION: Overall, sclerotic changes of hepatic cavernous hemangioma followed the morphological progression of background liver cirrhosis, while exophytic lesions tended to be free of size reduction.

Retrospective Comparison of Renal Ultrasonographic and Clinical Findings in Patients with Rhabdomyolysis.

BACKGROUND: This study evaluated the ultrasonographic and clinical findings of two groups with rhabdomyolysis, who showed abnormal or normal ultrasonographic findings of kidneys. METHODS: Two groups (n = 78) of abnormal (A) and normal (B) renal ultrasonographic findings were included. Multiple laboratory findings were assessed within 2 days before or after ultrasonography. Student's t-test or Mann-Whitney U-test was used for statistical analysis. RESULTS: The variable causes of rhabdomyolysis were intense exercise, burn, operation, shivering, and drug intoxication, etc. Group A (n = 26; M:F = 19:7) showed enlarged both kidneys, increased parenchymal thickness, and increased (n = 23, 88.5%) or decreased (n = 3, 11.5%) cortical echogenicity. Group A also showed elevated blood urea nitrogen (BUN), creatinine, potassium, and prolonged activated partial thromboplastin time (aPTT), compared with those in Group B (n = 52; M:F = 36:16), and these results were statistically significant (P < 0.01). The myoglobin in serum and urine, creatine kinase, prothrombin time, dark urine, and microscopic hematuria were not statistically different between the two groups. CONCLUSION: Patients with elevated BUN, creatinine, potassium, and prolonged aPTT showed the ultrasonographic findings of acute kidney injury, but other parameters were not statistically different between the two groups.

Efficacy of a paclitaxel-eluting biliary metal stent with sodium caprate in malignant biliary obstruction: a prospective randomized comparative study.

BACKGROUNDS: The placement of a self-expandable metal stent (SEMS) is widely used in patients with unresectable malignant biliary obstructions, but SEMSs are susceptible to occlusion by tumor ingrowth or overgrowth. The efficacy and safety of a novel paclitaxel-eluting biliary metal stent incorporating sodium caprate (MSCPM-III) were compared prospectively with those of a covered metal stent (CMS) in patients with malignant biliary obstructions. METHODS: Patients with unresectable distal malignant biliary obstructions (n = 106) were prospectively enrolled in this study at multiple treatment centers. Stents were placed endoscopically: MSCPM-III in 54 patients and CMS in 51 patients. The patients received systemic chemotherapy regimens according to their disease characteristics. RESULTS: The two groups did not differ significantly in basic characteristics or mean follow-up period. Stent occlusion occurred in 14 patients who received MSCPM-III and in 11 patients who received CMS. Time to recurrent biliary obstruction (RBO) and survival time did not differ significantly between the two groups (P  = 0.84 and P = 0.29, respectively). However, tumor size at 2 months after stent insertion was significantly decreased in patients in the MSCPM-III group with bile duct cancers or those who experienced stent migration compared with the CMS group. Complications, including cholangitis and pancreatitis, were found to be acceptable in both groups. CONCLUSIONS: Although compared with a CMS the MSCPM-III did not significantly influence time to RBO or survival duration in patients with malignant biliary obstructions, MSCPM-III reduced tumor volume and was used safely in humans.

Hepatic cavernous hemangiomas: long-term (> 5 years) follow-up changes on contrast-enhanced dynamic computed tomography or magnetic resonance imaging and determinant factors of the size change.

PURPOSE: To investigate the very long-term (> 5 years) follow-up changes of hepatic cavernous hemangiomas and to evaluate possible determinant factors for the changes. MATERIALS AND METHODS: Among 1115 consecutive patients suspected of having hepatic hemangiomas based on imaging features, 101 patients with comparable computed tomography or magnetic resonance imaging data during a 5-year follow-up interval in the Picture Archiving and Communication System were analyzed. Two radiologists independently determined the largest dimension of each lesion on axial images. In addition to background liver fibrosis or steatosis on imaging, histories of use of chemotherapeutic agents were checked from the patients' records. The final size change of the hemangioma was categorized into three groups compared with the initial diameter (increased, > 120%; no change, 80-120%; decreased, < 80%). RESULTS: Among the 101 hemangiomas, 32 lesions (31.7%) were enlarged and 21 lesions (20.8%) were shrunken during intervals of 60-157 (median, 81) months. Younger patients showed a higher prevalence of lesion enlargement (mean age: enlarged, 47.3 years; no change, 52.8 years; shrunken, 57.1 years; p = 0.003). In 15 patients with cirrhosis, the lesions (shrunken, n = 7; enlarged, n = 1) showed a higher tendency of size decrease (p = 0.009), whereas other factors did not show statistical significance (p > 0.05). Only a minor proportion (1%, n = 1) of the lesions showed size fluctuation during follow-up. CONCLUSION: During the long-term (5-13 years) follow-up, about 50% of the hepatic hemangiomas were enlarged or shrunken to > 20% of the initial diameter. Aside from the cirrhosis and aging factors, the size changes seemed sporadic.

Optimization of Split-Bolus CT Urography: Effect of Differences in Allocation of Contrast Medium and Prolongation of Imaging Delay.

OBJECTIVE: The purpose of this study was to find the optimal allocation ratio of contrast medium (CM) in split-bolus CT urography (CTU) and to investigate the effect of increased imaging delays for synchronous nephrographic-excretory phase imaging. SUBJECTS AND METHODS: One hundred ninety-two patients were randomly assigned to one of three protocols with different allocation ratios of CM: group A, 30% of CM at first bolus and 70% of CM at second bolus; group B, 70% and 30%; or group C, 50% and 50%. Saline (250 mL) was administered after the first CM bolus. Patients were subdivided by different imaging delay times (8, 10, 12, and 14 minutes). The attenuation values of the renal cortex and medulla were measured, and the opacification and maximal caliber of each segment of the ureter were evaluated. RESULTS: Renal cortical enhancement was significantly higher in group A (mean ± SD, 145.9 ± 17.5 HU) than group B (120.6 ± 106.3 HU). No significant difference in renal parenchymal enhancement was found with increased imaging delay times. The opacification and maximal caliber of each ureter segment showed no significant difference with different allocation ratios of CM or increased imaging delay times. CONCLUSION: A split-bolus CTU protocol with a larger CM volume administered at the second injection and an 8-minute imaging delay was the optimal protocol with regard to opacification of the ureter, renal parenchymal enhancement, and shorter examination time.

Percutaneous biliary approach as a successful rescue procedure after failed endoscopic therapy for drainage in advanced hilar tumors.

BACKGROUND AND AIM: Palliative endoscopic or percutaneous biliary drainage is used for unresectable advanced hilar cancer (HC). The best option for drainage in Bismuth type III or IV HC has not been established. The aims of this study are to identify factors predictive of endoscopic stenting failure and evaluate the effectiveness of rescue percutaneous stenting in patients with advanced HC. METHODS: Data from 110 patients with inoperable advanced HC were retrospectively reviewed. All received bilateral self-expandable metallic stents. Patients were divided into three groups: I, successful initial endoscopic stenting; II, unsuccessful initial endoscopic stenting, followed by percutaneous stenting; and III, initial percutaneous stenting. We analyzed clinical results and radiologic tumor characteristics. RESULTS: Baseline characteristics and clinical outcomes of all groups were similar, except the hospital stay was longer in group III than group I. Technical success rate was higher in groups II and III (100%) than in group I (72.4%). The functional success rate, stent patency time, patient survival time, and complication rate were similar between groups. Endoscopic stenting failed because of guide-wire passage failure (n = 12) or stent passage failure (n = 7). The only factor significantly associated with endoscopic failure was a smaller left intrahepatic duct-common bile duct angle. CONCLUSIONS: As clinical outcomes were generally similar between approaches, percutaneous stenting is recommended for patients with Bismuth type III or IV advanced HC. Acute left intrahepatic duct-common bile duct angulation predicts endoscopic stenting failure. If endoscopic stenting fails, immediate conversion to the percutaneous approach is a necessary and effective rescue method.

Multidetector CT findings of histopathologically proven peritoneal tuberculous cold abscesses.

PURPOSE: To evaluate the characteristic multidetector CT findings of peritoneal tuberculous (TB) cold abscesses. PATIENTS AND METHODS: The morphological characteristics of 48 peritoneal TB cold abscesses in 29 patients (male:female = 13:16; age range 16-75 years) were retrospectively evaluated. TB infection was histologically proven by acid fast bacilli (AFB) smear or culture, TB-polymerase chain reaction (PCR), or histopathological specimen diagnosis. RESULTS: Seventeen abscesses (35.4%) were present in the right perihepatic space, 10 (20.8%) in the left subphrenic space, 6 (12.5%) in the right subphrenic space, 4 (8.3%) in the pelvic cavity, 3 (6.3%) in the left perihepatic space, 3 (6.3%) in the right lower quadrant, and so on. The abscess contents ranged from 10.4 to 61.4 Hounsfield units. Internal septa (64.6%), central necrotic lymphadenopathy (55.2%), and TB coinfections in other organs (65.5%) were observed. TB infection was histopathologically confirmed from the surgical specimens in 17 patients and other 4 patients revealed the positive TB-PCR results from the peritoneal fluid. Ten patients (34.5%) had a recent history of TB peritonitis with ascites. CONCLUSION: Peritoneal TB cold abscesses were commonly found in the right perihepatic and subphrenic spaces and revealed higher density of internal content, frequent internal septa, central necrotic lymphadenopathy, and high TB coinfections in other organs.

Feasibility of 5-minute delayed transition phase imaging with 30° flip angle in gadoxetic acid-enhanced 3D gradient-echo MRI of liver, compared with 20-minute delayed hepatocyte phase MRI with standard 10° flip angle.

OBJECTIVE: The purpose of this study was to compare 5-minute delayed transitional phase imaging using a 30° flip angle (hereafter, 5 min-FA30) and 20-minute hepatocyte phase imaging using a 10° flip angle (hereafter, 20 min-FA10) in gadoxetic acid-enhanced MRI for focal hepatic lesion detection and lesion-to-liver contrast-to-noise ratio (CNR), and to determine whether 5 min-FA30 could replace 20 min-FA10 with a 15-minute time saving. MATERIALS AND METHODS: One hundred sixteen patients with 282 focal hepatic lesions (size range, 0.2-12.5 cm; malignant, n = 146; benign, n = 136) underwent gadoxetic acid-enhanced MRI with 5 min-FA30 and 20 min-FA10 with a 3D T1-weighted gradient-echo sequence. Three radiologists independently assessed the presence of focal hepatic lesions using a 4-point scale, and detection sensitivity of focal hepatic lesions was calculated. Lesion-to-liver CNRs were calculated and compared in two image groups. RESULTS: There was no significant difference in detection sensitivity of focal hepatic lesions for all three readers between 5 min-FA30 (mean, 95.4%) and 20 min-FA10 (mean, 95.6%), irrespective of lesion size or malignancy. The mean CNR on 5 min-FA30 (167.9 ± 84.1) was significantly higher than that on 20 min-FA10 (160.2 ± 79.5). However, the mean CNR difference between the two image groups was relatively small (7.8 ± 41.9). CONCLUSION: Compared with 20 min-FA10, 5 min-FA30 provided higher CNR and similar sensitivity. These findings indicate that 5 min-FA30 could replace 20-min delayed hepatocyte phase imaging using a 10° flip angle with similar diagnostic performance and 15 minutes of time saving.

Evaluation of lateral pelvic nodes in patients with advanced rectal cancer.

OBJECTIVE: The purpose of this article is to discuss the importance of lateral pelvic lymph node metastasis as a predictor of local recurrence and survival in patients with advanced rectal cancer. CONCLUSION: Prediction of lateral pelvic nodal staging on MRI shows high accuracy compared with the other imaging modalities. Diffusion-weighted MRI or (18)F-FDG PET/CT may be helpful to assesses lateral pelvic lymph node metastasis.

Assessment of angiogenesis of hepatocellular carcinoma using dynamic contrast enhanced MR and histopathologic correlation in an experimental rat model.

BACKGROUND/AIMS: To assess the perfusion parameters and angiogenesis of HCC using dynamic contrast enhanced(DCE) MR and to correlate it with histopathologic findings in an experimental rat model. METHODOLOGY: Twenty rats were continuously infused with diethylnitrosamine (DEN) for tumor induction. After 32 to 36 weeks of DEN treatment, the rats underwent MRI of the liver with a 3-T MR imaging system. Perfusion parametric maps and perfusion parameters such as, time to peak (TTP) and peak enhancement (PE) were obtained by using a commercially available software package. The nodules were correlated precisely to DCE MR images. RESULTS: A total of 13 nodules were found in 12 rats; 5 dysplastic nodule (DN)s were identified in 5 rats and 8 HCCs (3 Edmonson grade I, 2 Edmonson grade I-II, 3 Edmonson grade II) were found in 7 rats. There were significant differences in mean values of PE and HPH (histogram peak height) of PE between DN and HCC. Mean value and HPH of PE showed statistically significant correlation with tumor grade. CONCLUSIONS: There were significant differences in perfusion parameters between DN and HCC. DCE MR imaging can be used in the differential diagnosis and management of liver disease in hepatocarcinogenesis.

Usefulness of a lead shielding device for reducing the radiation dose to tissues outside the primary beams during CT.

PURPOSE: This study was done to investigate the efficacy of a lead shield in protecting the tissues outside the primary beams, such as the breast and thyroid, by measurement of the entrance skin dose during CT of the brain, neck, abdomen, and lumbar spine. MATERIALS AND METHODS: Institutional Review Board approval was obtained. This study included 150 patients (male:female 25:125, age range 15-45 years). In females, brain, lumbar spine, and abdominal CT scans, pre-/post-contrast neck CT scans, and post-contrast liver dynamic CT scans were performed. In males, brain CT scans only were performed. Breast shielding was performed in all females, and thyroid shielding was conducted in patients with brain CT. During all CT studies, the left breast or left thyroid was shielded using a lead shield, and the contralateral side was left unshielded. Thus, each breast or thyroid measurement had its own control for the same demographic data. The efficacy of the shielding of both breasts and thyroids during CT was assessed. RESULTS: During brain, abdominal, lumbar, pre-/post-contrast neck, and post-contrast liver dynamic CT, 33.5, 26.0, 17.4, 26.5, and 16.2 % of the breast skin dose were reduced, respectively. During brain CT, the thyroid skin dose was reduced by 17.9 % (females) and 20.6 % (males). There were statistically significant differences in the skin doses of shielded organs (p < 0.05). Breast shielding during neck and liver dynamic CT was the most effective compared with breast or thyroid shielding during other CT scans. CONCLUSIONS: We recommend breast shielding during neck and liver dynamic CT in young female patients to avoid unnecessary radiation exposure.

Preoperative evaluation of lymphovascular invasion using high-resolution pelvic magnetic resonance in patients with rectal cancer: a 2-year follow-up study.

OBJECTIVES: The objectives of this study were to preoperatively evaluate lymphovascular invasion (LVI) using pelvic magnetic resonance (MR) in patients with rectal cancer and to determine the correlation with distant metastasis rate. METHODS: If the mesorectal perivascular infiltrative signal was visible on pelvic MR imaging, the possibility of LVI was recorded. Distant metastatic lesions were also recorded at the time of the initial diagnostic workup and over a 2-year follow-up period. RESULTS: Fifteen (68.2%) of the 22 LVI patients showed mesorectal perivascular infiltrative signals on pelvic MRI. For the prediction of LVI in rectal cancer, MR had a sensitivity of 68.2% and a specificity of 93.2. The initial distant metastasis rate was significantly higher in patients with MR LVI (52%) than in patients without MR LVI (5.7%) (P < 0.0001). CONCLUSIONS: On pelvic MR, the presence of mesorectal perivascular infiltration by nodes is a specific sign of LVI in rectal cancer, and the presence of LVI is a predictor of distant metastasis.

CT angiography of the renal arteries: comparison of lower-tube-voltage CTA with moderate-concentration iodinated contrast material and conventional CTA.

OBJECTIVE: The objective of our study was to investigate the feasibility of an 80-kVp protocol using a moderate-concentration contrast medium (CM) for CT angiography of the renal arteries by comparison with a conventional 120-kVp protocol using a high-concentration CM. SUBJECTS AND METHODS: Attenuation values and signal-to-noise ratios (SNRs) were determined in a phantom for the 120-kVp protocol with a high-concentration CM and the 80-kVp protocol with a moderate-concentration CM. In addition, 50 patients were prospectively enrolled in the study: 25 were scanned with 120 kVp and 200 effective mAs (mAs(eff)) after the administration of 110 mL of high-concentration CM (370 mg I/mL), and the other 25 were scanned with 80 kVp and 585 mAs(eff) after the administration of 110 mL of moderate-concentration CM (300 mg I/mL). Images of the two groups were compared in terms of arterial attenuation, SNR, contrast-to-noise ratio (CNR), and subjective degree of arterial enhancement and image quality. RESULTS: The mean attenuation of the main renal artery was significantly higher (p < 0.001) in the 80-kVp group who received moderate-concentration CM (mean ± SD, 370.0 ± 65.0 HU) than in the 120-kVp group who received high-concentration CM (269.9 ± 27.8 HU) without significant differences in SNR and CNR values. The 80-kVp protocol had significantly higher quality scores for arterial enhancement, sharpness of the artery, and overall diagnostic quality compared with the 120-kVp protocol. The effective dose of the 80-kVp protocol (4.5 mSv) was 8.2% lower than that of the 120-kVp protocol (4.9 mSv). CONCLUSION: The use of 80 kVp with moderate-concentration CM could improve arterial enhancement and provide superior image quality with a smaller amount of iodine and a lower radiation dose.

Computed tomographic venography for varicose veins of the lower extremities: prospective comparison of 80-kVp and conventional 120-kVp protocols.

OBJECTIVE: To prospectively investigate the feasibility of an 80-kilovolt (peak) (kVp) protocol in computed tomographic venography for varicose veins of the lower extremities by comparison with conventional 120-kVp protocol. METHODS: Attenuation values and signal-to-noise ratio of iodine contrast medium (CM) were determined in a water phantom for 2 tube voltages (80 kVp and 120 kVp). Among 100 patients, 50 patients were scanned with 120 kVp and 150 effective milliampere second (mAs(eff)), and the other 50 patients were scanned with 80 kVp and 390 mAs(eff) after the administration of 1.7-mL/kg CM (370 mg of iodine per milliliter). The 2 groups were compared for venous attenuation, contrast-to-noise ratio, and subjective degree of venous enhancement, image noise, and overall diagnostic image quality. RESULTS: In the phantom, the attenuation value and signal-to-noise ratio value for iodine CM at 80 kVp were 63.8% and 33.0% higher, respectively, than those obtained at 120 kVp. The mean attenuation of the measured veins of the lower extremities was 148.3 Hounsfield units (HU) for the 80-kVp protocol and 94.8 HU for the 120-kVp protocol. Contrast-to-noise ratio was also significantly higher with the 80-kVp protocol. The overall diagnostic image quality of the 3-dimensional volume-rendered images was good with both protocols. The subjective score for venous enhancement was higher at the 80-kVp protocol. The mean volume computed tomography dose index of the 80-kVp (5.6 mGy) protocol was 23.3% lower than that of the 120-kVp (7.3 mGy) protocol. CONCLUSION: The use of the 80-kVp protocol improved overall venous attenuation, especially in perforating vein, and provided similarly high diagnostic image quality with a lower radiation dose when compared to the conventional 120-kVp protocol.

Nodal staging of rectal cancer: high-resolution pelvic MRI versus ¹8F-FDGPET/CT.

AIM: To compare high-resolution pelvic magnetic resonance imaging (MRI) with positron emission tomography (PET)/computed tomography (CT) for the preoperative assessment of nodal staging in rectal cancer. MATERIALS AND METHODS: Thirty patients who had surgery for rectal cancer were retrospectively enrolled during a 6-month period. Each patient underwent high-resolution pelvic MRI and PET/CT preoperatively within the same week. An experienced radiologist predicted nodal staging on MR, and an experienced nuclear medicine physician similarly predicted nodal staging on PET/CT. Their predictions were compared with pathologic staging results, retrospectively. RESULTS: The accuracies of nodal status prediction from MR and PET/CT were 83% and 70%, respectively. Magnetic resonance imaging had a sensitivity of 94% and a specificity of 67%, whereas PET/CT had a sensitivity of 61% and a specificity of 83%. A combination of MRI and PET/CT revealed a sensitivity of 94%, a specificity of 83%, and an accuracy of 90%. CONCLUSION: High-resolution pelvic MRI was more accurate than PET/CT for the prediction of regional nodal status. Magnetic resonance imaging had a high sensitivity and PET/CT had a high specificity for N staging in rectal cancer.

A case of mass-forming splenic tuberculosis: MRI findings with emphasis of diffusion-weighted imaging characteristics.

Tuberculosis remains one of the most prevalent and fatal infectious diseases in spite of considerable improvements in medical science. The diagnosis and treatment of extrapulmonary tuberculosis involving the abdomen is still complicated owing to vague or non-specific clinical features. Although rare, isolated splenic involvement is one of the important manifestations of extrapulmonary tuberculosis, and imaging suspicion of the disease is essential. We report a case of surgically confirmed mass-forming splenic tuberculosis showing a layered pattern consisting of caseous necrosis with profound restriction of water molecules surrounded by an irregular rind of granulation tissue with less diffusion restriction on diffusion-weighted magnetic resonance imaging (DWI). In the differential diagnosis of neoplastic or non-neoplastic mass-forming lesions involving the spleen, this unique DWI feature could be helpful in characterizing splenic tuberculosis. The patient has been in clinically disease free status for nearly 20 months after splenectomy.