In vitro study of the embolic characteristics of imipenem/cilastatin particles

BACKGROUND

Imipenem/cilastatin (IPM/CS) has long been administered intravenously as a carbapenem antibiotic. However, since this agent is poorly soluble in liquid, occasional reports have described its use as a short-acting, temporary embolic agent. The purpose of this study was to elucidate the characteristics of IPM/CS particles, which are thought to have pain-relieving effects against osteoarthritis-related pain, as an embolic agent.

METHODS

Three aspects of IPM/CS as an embolic agent were evaluated in vitro: particle size; particle shape; and change in particle size over time. For particle size, the long diameter was measured.

RESULTS

Mean particle size (n=244) was 29.2±12.0 µm (range, 1-60 µm). Shape (n=109) was round in 18.35%, elliptical in 11.93%, and polygonal in 69.72%, showing that most particles were polygonal. In observations of changes in particle size over time (n=9), particles had decreased to 75% of their original size at 82±10.7 min, 50% at 89.3±9.14 min, 25% at 91.3±8.74 min, complete dissolved at 91.8±9.02 min. A rapid shrinkage in diameter was seen in the final period.

CONCLUSIONS

IPM/CS particles are ultrafine and the majority display a polygonal shape. This substance shows ultra-short embolic activity. This study revealed the characteristics of a substance that demonstrates an embolic effect not found in existing embolic materials.

Quantitative Magnetic Resonance Imaging for the Pancreas: Current Status

ABSTRACT

Magnetic resonance imaging (MRI) is important for evaluating pancreatic disorders, and anatomical landmarks play a major role in the interpretation of results. Quantitative MRI is an effective diagnostic modality for various pathologic conditions, as it allows the investigation of various physical parameters. Recent advancements in quantitative MRI techniques have significantly improved the accuracy of pancreatic MRI. Consequently, this method has become an essential tool for the diagnosis, treatment, and monitoring of pancreatic diseases. This comprehensive review article presents the currently available evidence on the clinical utility of quantitative MRI of the pancreas.

Changes in pancreatic exocrine function, fat and fibrosis in diabetes mellitus: analysis using MR imaging

OBJECTIVE

To evaluate the relationships between hemoglobin A1c (HbA1c) levels with exocrine pancreatic function using cine-dynamic magnetic resonance cholangiopancreatography (MRCP) and the pancreatic parenchyma using fat-suppressed T1 mapping and the proton density fat fraction (PDFF).

METHODS

Patients who underwent 3T-MRI and HbA1c measurement were retrospectively recruited. MRI included cine-dynamic MRCP with a spatially selective inversion-recovery (SS-IR) pulse, fat-suppressed Look-Locker T1 mapping and multiecho 3D Dixon-based PDFF mapping. The pancreatic exocrine secretion grade on cine-dynamic MRCP, T1 values, and PDFF were analyzed in non-diabetic (n = 32), pre-diabetic (n = 44) and diabetic (n = 23) groups defined using HbA1c.

RESULTS

PDFF was weakly correlation with HbA1c (ρ = 0.30, p = 0.002). No correlations were detected between HbA1c and secretion grade (ρ = - 0.16, p = 0.118) or pancreatic parenchymal T1 (ρ = 0.13, p = 0.19). The secretion grade was comparable between the three groups. The T1 value was higher in diabetic (T1 = 1006.2+/- 224.8 ms) than in non-diabetic (T1 = 896.2+/- 86.3 ms, p = 0.010) and pre-diabetic (T1 = 870.1+/- 91.7 ms, p < 0.010) patients. The PDFF was higher in diabetic (FF = 11.8+/- 8.7 %) than in non-diabetic (FF = 6.8+/- 4.2 %, p = 0.014) patients.

CONCLUSION

Pancreatic exocrine function, T1, and FF showed no correlation with HbA1c. Pancreatic T1 and fat fraction is increased in patients with Type 2 diabetes mellitus.

ADVANCES IN KNOWLEDGE

This study demonstrates unaffected exocrine function in pre-diabetes and diabetes and confirms that pancreatic parenchymal T1 and FF are increased in patients with diabetes.

Comparison Between Amide Proton Transfer Magnetic Resonance Imaging Using 3-Dimensional Acquisition and Diffusion-Weighted Imaging for Characterization of Prostate Cancer: A Preliminary Study

OBJECTIVE

This study aimed to compare diagnostic performance for tumor detection and for assessment of tumor aggressiveness in prostate cancer (PC) between amide proton transfer magnetic resonance imaging (MRI) with 3-dimensional acquisition (3DAPT) and diffusion-weighted imaging.

METHODS

The subjects were 23 patients with 27 pathologically proven PCs who underwent 3T multiparametric MRI. With reference to the pathology findings, 2 readers in consensus identified the location of PC on multiparametric MRI and measured APT signal intensity (APT SI [%]) and mean apparent diffusion coefficient (ADC) of the benign region and each PC lesion.

RESULTS

The mean ADC showed a significant difference between benign regions and PC lesions (0.74 ± 0.15 vs 1.37 ± 0.21, P < 0.001), whereas APT SI did not ( P = 0.091). Lesion APT SI was significantly higher and lesion ADC was significantly lower in PCs with Gleason group (GG) ≥3 than in PCs with GG ≤2 (3.37 ± 1.30 vs 1.78 ± 0.67, P < 0.001, and 0.71 ± 0.18 vs 0.79 ± 0.10, P = 0.038, respectively). The APT SI was significantly higher in GG3 than in GG1, in GG3 than in GG2, and in GG4 than in GG2 ( P = 0.009, P = 0.001, and P = 0.006, respectively). The area under the curve for separating tumor lesions and benign regions was 0.601 for 3DAPT and 0.983 for ADC ( P < 0.001). The area under the curve for separating tumors with GG ≤2 from tumors with GG ≥3 was 0.912 for 3DAPT and 0.734 for ADC ( P = 0.172).

CONCLUSIONS

In patients with PC, it might be preferable to use ADC to discriminate benign from malignant tissue and use APT SI for assessment of tumor aggressiveness.

An Ancillary Method for Adrenal Venous Sampling in Cases in Which Right Adrenal Vein Sampling Is Difficult

Catheterization of the right adrenal vein (rt.AdV) to obtain blood samples can often be difficult. The aim of the present study was to investigate whether blood sampling from the inferior vena cava (IVC) at its juncture with the rt.AdV can be an ancillary to sampling of blood directly from the rt.AdV. This study included 44 patients diagnosed with primary aldosteronism (PA) in whom AVS with adrenocorticotropic hormone (ACTH) was performed, resulting in a diagnosis of idiopathic hyperaldosteronism (IHA) (n = 24), and patients diagnosed with unilateral aldosterone-producing adenoma (APA) (n = 20; rt.APA = 8, lt.APA = 12). In addition to regular blood sampling, blood was also sampled from the IVC, as the substitute rt.AdV [S-rt.AdV]. Diagnostic performance with the conventional lateralized index (LI) and the modified LI using the S-rt.AdV were compared to examine the utility of the modified LI. The modified LI of the rt.APA (0.4 ± 0.4) was significantly lower than those of the IHA (1.4 ± 0.7) (p < 0.001) and the lt.APA (3.5 ± 2.0) (p < 0.001). The modified LI of the lt.APA was significantly higher than those of the IHA (p < 0.001) and rt.APA (p < 0.001). Likelihood ratios to diagnose rt.APA and lt.APA using the modified LI with threshold values of 0.3 and 3.1 were 27.0, and 18.6, respectively. The modified LI has the potential to be an ancillary method for rt.AdV sampling in cases in which rt.AdV sampling is difficult. Obtaining the modified LI is extremely simple, which might complement conventional AVS.

Comparison of single-shot EPI and multi-shot EPI in prostate DWI at 3.0 T

In prostate MRI, single-shot EPI (ssEPI) DWI still suffers from distortion and blurring. Multi-shot EPI (msEPI) overcomes the drawbacks of ssEPI DWI. The aim of this article was to compare the image quality and diagnostic performance for clinically significant prostate cancer (csPC) between ssEPI DWI and msEPI DWI. This retrospective study included 134 patients with suspected PC who underwent 3.0 T MRI and subsequent MRI-guided biopsy. Three radiologists independently assessed anatomical distortion, prostate edge clarity, and lesion conspicuity score for pathologically confirmed csPC. Lesion apparent diffusion coefficient (ADC) and benign ADC were also calculated. In 17 PC patients who underwent prostatectomy, three radiologists independently assessed eight prostate regions by DWI score in PI-RADS v 2.1. Anatomical distortion and prostate edge clarity were significantly higher in msEPI DWI than in ssEPI DWI in the three readers. Lesion conspicuity score was significantly higher in msEPI DWI than in ssEPI DWI in reader 1 and reader 3. Regarding discrimination ability between PC with GS ≤ 3 + 4 and PC with GS ≥ 4 + 3 using lesion ADC, AUC was comparable between ssEPI DWI and msEPI DWI. For diagnostic performance of csPC using DWI score, AUC was comparable between msEPI DWI and ssEPI DWI in all readers. Compared with ssEPI DWI, msEPI DWI had improved image quality and similar or higher diagnostic performance.

Value of 3-T MR imaging in intraductal papillary mucinous neoplasm with a concomitant invasive carcinoma

OBJECTIVES

To examine the value of 3-T MRI for evaluating the difference between the pancreatic parenchyma of intraductal papillary mucinous neoplasm with a concomitant invasive carcinoma (IPMN-IC) and the pancreatic parenchyma of patients without an IPMN-IC.

METHODS

A total of 132 patients underwent abdominal 3-T MRI. Of the normal pancreatic parenchymal measurements, the pancreas-to-muscle signal intensity ratio in in-phase imaging (SIR-I), SIR in opposed-phase imaging (SIR-O), SIR in T2-weighted imaging (SIR-T2), ADC (×10^-3 mm²/s) in DWI, and proton density fat fraction (PDFF [%]) in multi-echo 3D DIXON were calculated. The patients were divided into three groups (normal pancreas group: n = 60, intraductal papillary mucinous neoplasm (IPMN) group: n = 60, IPMN-IC group: n = 12).

RESULTS

No significant differences were observed among the three groups in age, sex, body mass index, prevalence of diabetes mellitus, and hemoglobin A1c (p = 0.141 to p = 0.657). In comparisons among the three groups, the PDFF showed a significant difference (p < 0.001), and there were no significant differences among the three groups in SIR-I, SIR-O, SIR-T2, and ADC (p = 0.153 to p = 0.684). The PDFF of the pancreas was significantly higher in the IPMN-IC group than in the normal pancreas group or the IPMN group (p < 0.001 and p < 0.001, respectively), with no significant difference between the normal pancreas group and the IPMN group (p = 0.916).

CONCLUSIONS

These observations suggest that the PDFF of the pancreas is associated with the presence of IPMN-IC.

KEY POINTS

• The cause and risk factors of IPMN with a concomitant invasive carcinoma have not yet been clarified. • The PDFF of the pancreas was significantly higher in the IPMN-IC group than in the normal pancreas group or the IPMN group. • Pancreatic PDFF may be a potential biomarker for the development of IPMN with a concomitant invasive carcinoma.

Mixed epithelial and stromal tumor of the kidney composed mainly of solid components: A case report

Mixed epithelial and stromal tumor (MEST) is a relatively rare lesion of mixed epithelial and mesenchymal origin, consisting of epithelial components that form cysts and stromal cells that are positive for estrogen and progesterone receptors. The present case was a 54-year-old female who presented with hematuria. Abdominal ultrasonography revealed a 41 x 30 mm tumor in the right kidney, with the tumor protruding outward in the direction of the renal pelvis. Dynamic contrast-enhanced computed tomography and magnetic resonance imaging confirmed a solid tumor in the right kidney that showed gradual contrast enhancement and contained a central non-enhancing area with the appearance of a cystic component. Based on the imaging findings, the provisional diagnosis was papillary renal cell carcinoma or angiomyolipoma with epithelial cysts. Right nephrectomy was performed and the tumor was confirmed histopathologically as MEST. We report a very rare case of MEST that was composed mainly of solid components.

A case of primary aortic sarcoma with tumor infarction after stent graft placement

Primary aortic sarcoma is a very rare disease, and most primary aortic tumors are malignant mesenchymal tumors. We present the case of a 62-year-old man with sudden epigastric and back pain. Contrast-enhanced computed tomography (CT) revealed a mass lesion about 33.8 mm in diameter, in contact with the left side of the abdominal aorta. Impending rupture of an abdominal aortic aneurysm was suspected, so cardiovascular surgery for stent graft placement was performed the same day. Symptoms immediately improved and CT at 3 months postoperatively showed a marked decrease in lesion size, but the lesion subsequently grew again. Fluorodeoxyglucose (FDG)-positron emission tomography/CT was performed due to the possibility of malignant solid tumor, revealing markedly increased FDG accumulation (maximum standardized uptake value, 36.95) in the mass lesion. Primary aortic sarcoma was diagnosed from thoracoscopic biopsy. Here, we report a primary aortic sarcoma that shrank due to tumor infarction after stent graft placement, followed by tumor regrowth.

Evaluation of liver fibrosis using hepatic extracellular volume fraction by contrast-enhanced computed tomography before and after direct-acting antiviral therapy in patients with chronic hepatitis C infection: comparison with serological liver fibrosis markers

OBJECTIVE

To evaluate time-dependent changes in hepatic extracellular volume (ECV) fraction using contrast-enhanced CT (CECT) and serological liver fibrosis markers, the fibrosis-4 (FIB-4) index and aspartate aminotransferase to platelet ratio index (APRI), before and after direct-acting antiviral therapy (DAA) for hepatitis C virus (HCV) infection.

METHODS

41 HCV-infected patients who achieved sustained virological response (SVR) after DAA (SVR group) and 10 control patients (untreated or unresponsive to treatment) who underwent CECT and serum biochemical tests before or after the first examination/DAA (T1) and at intervals thereafter (T2:<6 months after T1, T3: at 6-12 months, T4: at 12-24 months, and T5:>24 months) were evaluated.

RESULTS

In the control group, ECV fractions remained relatively unchanged through the study, and significant differences in FIB-4 index comparisons and APRI comparisons were only seen between the T2 and T4 values (p = 0.046 and p = 0.028, respectively). In the SVR group, ECV fractions were significantly different between T1 and T4 and T1 and T5 (p = 0.046 and 0.022, respectively), and both FIB-4 index and APRI were significantly different between T1 and all other time points (p = 0.017 to p < 0.001 and p = 0.001 to p < 0.001, respectively).

CONCLUSION

After DAA, ECV fraction decreased slowly, suggesting an improvement in hepatic fibrosis, while serological liver fibrosis markers decreased immediately, probably due to improvement in hepatic inflammation.

ADVANCES IN KNOWLEDGE

ECV fraction has the potential to be a non-invasive biomarker for the assessment of liver fibrosis after direct-acting antiviral therapy.

Hemodynamic changes of abdominal organs after CT colonography with transrectal administration of CO2: evaluation with early-phase contrast-enhanced dynamic CT

PURPOSE

To evaluate the hemodynamic changes in the liver, pancreas, gastric mucosa and abdominal vessels in early-phase dynamic contrast-enhanced (DCE) CT immediately after CT colonography (CTC) with carbon dioxide expansion.

MATERIALS AND METHODS

This study included 82 patients with DCE-CT after CTC (CTC group) and 77 patients without CTC (control group). Contrast enhancement values of the gastric mucosa, liver, pancreas, portal vein (PV), splenic vein (SpV), superior mesenteric vein (SMV), and inferior mesenteric vein (IMV) in early-phase CT were measured. The presence of hepatic pseudolesions were also recorded.

RESULTS

The mean contrast enhancement values of the gastric mucosa, pancreas and SpV in the CE-CTC group were significantly lower than those in the control group (p < 0.001, p < 0.001, p = 0.014). Conversely, the mean contrast enhancement values of the liver, PV, SMV and IMV in the CE-CTC group were significantly higher than those in the control group (p = 0.003, p = 0.013, p < 0.001, p < 0.001). Hypovascular hepatic pseudolesions were seen in early-phase CT in six patients after CTC, while they were not seen in the control group.

CONCLUSIONS

On DCE-CT performed immediately after CTC with carbon dioxide expansion, it is important to be aware of the imaging findings induced by visceral hemodynamic changes.

Morphologic changes in hepatitis virus-related liver cirrhosis: Relationship to hemodynamics of portal vein on dynamic contrast-enhanced CT

INTRODUCTION

The morphologic changes in the compensated stage of liver cirrhosis (cLC) are not diffuse atrophic changes. With cLC lobar or segmental changes combined with atrophy of the right lobe and medial segment together with hypertrophy of the caudate lobe and lateral segment are commonly seen. The purpose of this study was to evaluate the morphologic changes in hepatitis virus-related liver cirrhosis in relationship to haemodynamics of the portal vein on dynamic contrast-enhanced computed tomography (DCE-CT) METHODS: This study included 72 patients, 46 with hepatitis virus-related cirrhosis and 26 with a normally functioning liver, who underwent DCE-CT. In cirrhosis patients, the morphologic change index (MCI) of the liver was calculated and categorised into two groups, high-MCI (MCI ≥ 0.4) (n = 21) and low-MCI (MCI < 0.4) (n = 25). Cross-sectional areas of the main, right and left portal veins and the intra-portal distribution from splenic venous flow were evaluated for their relationships with the MCI and compared among three groups (normal-control, low MCI and high MCI).

RESULTS

There was a significant difference in the cross-sectional area of the left portal vein between the high-MCI group and the low-MCI group (p = 0.013) and the control group (p = 0.008). A significant correlation was identified between the cross-sectional area of the left portal vein and the MCI (r = 0.508, p < 0.001).

CONCLUSION

Cross-sectional area of the left portal vein may be a factor related to morphologic changes in hepatitis virus-related liver cirrhosis and could be a possible index of the left portal venous flow volume.

IMPLICATIONS FOR PRACTICE

This study may be useful for predicting the degree of hepatic morphologic changes and the condition of cirrhosis in association with regional hepatic morphologic changes.

Influence of cholecystectomy on the flow dynamic pattern of bile in the extrahepatic bile duct: Assessment by cine-dynamic MRCP with spatially-selective IR pulse

PURPOSE

To evaluate the influence of cholecystectomy on the flow dynamic pattern of bile in the extrahepatic bile duct by using cine-dynamic MRCP with spatially-selective inversion-recovery (IR) pulse non-invasively.

MATERIALS AND METHODS

56 patients with cholecystectomy and 48 control subjects without cholecystectomy who underwent cine-dynamic MRCP with spatially-selective IR pulse at 1.5 T or 3 T (TR/TE, 4000 msec/500 msec; echo train spacing, 6.5 msec; echo train length, 172; section thickness, 50 mm; matrix, 320 × 320; field of view, 320 × 320 mm; bandwidth, 488 Hz; and inversion time, 2200 msec). In cine-dynamic MRCP, IR pulse with 20 mm width was placed on the common bile duct (CBD) to evaluate the movement of bile (antegrade and reversed bile flow). Cine-dynamic MRCP imaging was scanned every 15 s (imaging, 4 s; rest, 11 s) during 5 min to acquire a series of single-shot images (a total of 20 images). The frequency that antegrade or reversed bile flow was observed in the extrahepatic bile duct, and 5-point grading score based on the moving distance of antegrade or reversed bile flow were compared between the groups. Both groups were compared using the χ² and Mann-Whitney U tests (P < 0.05 considered significant).

RESULTS

Antegrade bile flow was observed more frequently in the cholecystectomy group than in the non-cholecystectomy group (5.1 times vs. 2.8 times, P = 0.008). Mean grading score of antegrade bile flow was significantly greater in the cholecystectomy group than in the non-cholecystectomy group (mean grade, 0.33 vs 0.21; P = 0.014). Regarding reversed bile flow, there were no significant differences in the frequency and grading score between cholecystectomy group and non-cholecystectomy group.

CONCLUSION

Antegrade bile flow was observed more frequently and predominantly in patients after cholecystectomy in cine-dynamic MRCP with spatially-selective IR pulse while reversed bile flow was observed equivalently.

Symptoms that are associated with decreased pancreatic enzyme flow: MRCP assessment

BACKGROUND

Pancreatic exocrine insufficiency is one of the causes of malabsorption syndrome. In many cases of malabsorption syndrome, pancreatic exocrine insufficiency can be treated with pancreatic enzyme replacement therapy. Therefore, it is important to detect pancreatic endocrine insufficiency as early and accurately as possible. Recent studies have shown that cine-dynamic MR cholangiopancreatography (MRCP) may be useful to evaluate pancreatic exocrine function PURPOSE: To identify abdominal symptoms that suggest decreased flow of pancreatic enzyme secretion for which cine-dynamic MRCP should be performed to diagnose pancreatic exocrine insufficiency.

STUDY TYPE

Prospective.

POPULATION

In all, 111 patients with various types of abdominal symptoms.

FIELD STRENGTH/SEQUENCE

5 T or 3 T, MRCP with spatially selective inversion recovery pulse (cine-dynamic MRCP).

ASSESSMENT

Cine-dynamic MRCP was performed and an 18-question clinical questionnaire on abdominal symptoms was administered. The secretion grade derived from cine-dynamic MRCP was compared between those answering "yes" and "no" for all 18 items STATISTICAL TESTS: Univariate analysis and further analyzed using multiple regression analysis. The associations between the secretion grade and the items in the clinical questionnaire were analyzed by univariate analysis and further analyzed using multiple regression analysis.

RESULTS

The following three items showed significantly negative correlations with secretion grade: Q9, Does your rectal gas smell foul? (β = -0.44, P = 0.001); Q13, Is stool quantity large? (β = -0.41, P = 0.001); and Q18, Are your stools soft? (β = -0.53, P < 0.001). No significant correlations with exocrine pancreatic function measured by cine-dynamic MRCP were seen for the remaining 15 abdominal symptom items.

DATA CONCLUSION

Abdominal symptoms that suggest decreased flow of pancreatic enzyme secretion were foul rectal gas, large stool, and soft stool. Pancreatic exocrine insufficiency due to decreased pancreatic enzyme flow may be suspected in patients with these abdominal symptoms.

LEVEL OF EVIDENCE

1 Technical Efficacy Stage: 3 J. Magn. Reson. Imaging 2019;50:417-423.

Alterations in apparent diffusion coefficient values of the kidney during the cardiac cycle: Evaluation with ECG-triggered diffusion-weighted MR imaging

PURPOSE

To evaluate dynamic changes in apparent diffusion coefficient (ADC) values of the kidney at different time points during the cardiac cycle using electrocardiographic (ECG)-triggered diffusion-weighted MR imaging in normal subjects, and to elucidate the differences in ADC values between the right and left kidneys during a cardiac cycle.

MATERIALS AND METHODS

The study was approved by our institutional review board and informed consent was obtained from subjects. Twenty healthy volunteers who underwent ECG-triggered diffusion-weighted MR imaging of the kidney were included. The differences in ADC values of each kidney during different cardiac phases were compared. Additionally, the differences in maximum and minimum ADC values between the right and left kidney were also evaluated.

RESULTS

ADC values in the right and left kidney changed significantly during the cardiac cycle (P < 0.00001). Maximum and minimum ADC values during the cardiac cycle of the left kidney were significantly higher (P = 0.026 and 0.017, respectively) than those of the right kidney. Maximum ADC value in the left kidney had a significantly strong positive correlation with the left renal vein ratio (r = 0.83, P < 0.00001). In the right kidney, maximum ADC showed a weakly positive correlation with the diameter of the right renal vein (r = 0.45, P = 0.048).

CONCLUSION

ADC values of the kidney obtained using ECG-triggered diffusion-weighted MR imaging change significantly during the cardiac cycle. Maximum (systolic) ADC during the cardiac cycle of the left kidney was significantly higher than that of the right kidney, probably due to the anatomical difference in the renal vein.

Assessment of clinical and magnetic resonance imaging features of de novo hypervascular hepatocellular carcinoma using gadoxetic acid-enhanced magnetic resonance imaging

AIM

To clarify the clinical and magnetic resonance imaging (MRI) features of de novo hypervascular hepatocellular carcinoma (HCC) using serial gadoxetic acid-enhanced MRI.

METHODS

The institutional review board approved this retrospective study. After review of 1007 MRI examinations in 240 patients with chronic liver disease, 17 newly developed hypervascular HCCs in 16 patients detected by follow-up from initial MRI examination without hepatocellular nodules were evaluated. The clinical and MRI findings such as previous treatment history for HCC, period to hypervascular HCC onset, presence or absence of hypovascular hypointense nodules on hepatobiliary phase before hypervascularization, and intralesional fat component were recorded or evaluated. Statistical evaluations included Fisher's exact test, χ² -test, and Mann-Whitney U-test.

RESULTS

In 17 HCCs, 12 (71%) were de novo hypervascular HCC without showing hypovascular hypointense nodule on hepatobiliary phase before hypervascularization (de novo group) and 5 (29%) were hypervascularized HCC developed during multistep hepatocarcinogenesis (multistep group). The incidence of previous treatment history for HCC in the de novo group (91%) was significantly higher than that in the multistep group (20%) (P = 0.013). The duration to hypervascular HCC onset from initial examination was shorter in the de novo group (mean, 291 days) than in the multistep group (mean, 509 days) (P = 0.035). The incidence of fat-containing lesion in the de novo group (0%) was lower than that in the multistep group (40%) (P = 0.074).

CONCLUSION

De novo hypervascular HCC is characterized by rapid growth, patients with previous treatment history for HCC, and lack of intralesional fat, compared to hypervascular HCC with multistep progression.

Differentiation of subtypes of renal cell carcinoma: dynamic contrast-enhanced magnetic resonance imaging versus diffusion-weighted magnetic resonance imaging

OBJECTIVE

The objective was to compare the performance of dynamic contrast-enhanced (DCE) and diffusion-weighted (DW) magnetic resonance (MR) imaging in the differentiation of subtypes of renal cell carcinoma (RCC).

MATERIALS/METHODS

This study included 45 renal tumors of clear cell (n=36) and non-clear-cell (n=9) RCC. The contrast enhancement ratios (CERs) and the apparent diffusion coefficient (ADC) values on MR imaging were compared between the clear cell and non-clear-cell RCC groups.

RESULTS

In the comparison of diagnostic performance between DCE and DW MR imaging, areas under the curves were 0.968 and 0.797 for the CERs of the corticomedullary and the ADC value.

CONCLUSION

The CER of the corticomedullary phase was more reliable in distinguishing between clear cell and non-clear-cell RCCs.

Imaging Outcomes of Liver Imaging Reporting and Data System Version 2014 Category 2, 3, and 4 Observations Detected at CT and MR Imaging

Purpose To determine the proportion of untreated Liver Imaging Reporting and Data System (LI-RADS) version 2014 category 2, 3, and 4 observations that progress, remain stable, or decrease in category and to compare the cumulative incidence of progression in category. Materials and Methods In this retrospective, longitudinal, single-center, HIPAA-compliant, institutional review board-approved study, 157 patients (86 men and 71 women; mean age ± standard deviation, 59.0 years ± 9.7) underwent two or more multiphasic computed tomographic (CT) or magnetic resonance (MR) imaging examinations for hepatocellular carcinoma surveillance, with the first examination in 2011 or 2012. One radiologist reviewed baseline and follow-up CT and MR images (mean follow-up, 614 days). LI-RADS categories issued in the clinical reports by using version 1.0 or version 2013 were converted to version 2014 retrospectively; category modifications were verified with another radiologist. For index category LR-2, LR-3, and LR-4 observations, the proportions that progressed, remained stable, or decreased in category were calculated. Cumulative incidence curves for progression were compared according to baseline LI-RADS category (by using log-rank tests). Results All 63 index LR-2 observations remained stable or decreased in category. Among 166 index LR-3 observations, seven (4%) progressed to LR-5, and eight (5%) progressed to LR-4. Among 52 index LR-4 observations, 20 (38%) progressed to a malignant category. The cumulative incidence of progression to a malignant category was higher for index LR-4 observations than for index LR-3 or LR-2 observations (each P < .001) but was not different between LR-3 and LR-2 observations (P = .155). The cumulative incidence of progression to at least category LR-4 was trend-level higher for index LR-3 observations than for LR-2 observations (P = .0502). Conclusion Observations classified according to LI-RADS version 2014 categories are associated with different imaging outcomes. (©) RSNA, 2016 Online supplemental material is available for this article.

Pancreatic adenocarcinomas without secondary signs on multiphasic multidetector CT: association with clinical and histopathologic features

PURPOSE

To determine the clinical, histopathologic and imaging features of pancreatic adenocarcinomas without secondary signs on dynamic CT.

MATERIALS AND METHODS

Seventy patients (mean age 70 years) with histologically proven pancreatic adenocarcinoma underwent preoperative contrast material-enhanced multiphasic multidetector CT before pancreatic resection. In each patient, clinical data including carbohydrate antigen 19-9, frequency of isoattenuating tumours, and presence of secondary signs and histopathologic findings such as tumour location, tumour stage, and microscopic infiltrative growth grade were evaluated.

RESULTS

Ten tumours (14%) were without secondary signs, and 60 (86%) were with secondary signs. Tumours without and with secondary signs were located in the uncinate process in 5 (50%) and 3 (5%), head in 3 (30%) and 29 (48%), body in 2 (20%) and 22 (37%), and tail in 0 (0%) and 6 (10%), respectively (p = .001). The frequency of isoattenuating pancreatic adenocarcinomas without secondary signs was significantly higher than those with secondary signs (p = 0.034). The tumour stage of pancreatic adenocarcinomas without secondary signs was earlier than that in tumours with secondary signs (p = 0.041).

CONCLUSIONS

Pancreatic adenocarcinomas without secondary signs is characterized by the presence of uncinate and isoattenuating tumours and earlier tumour stage compared to tumours with secondary signs.

KEY POINTS

Frequency of pancreatic adenocarcinomas without secondary signs on multiphasic CT is 14 . Pancreatic adenocarcinomas without secondary signs are common in the uncinate process. Pancreatic adenocarcinomas without secondary signs are common in isoattenuating tumours. Pancreatic adenocarcinomas without secondary signs are characterized by earlier-stage tumours.

Feasibility and safety of transfemoral intra-arterial chemotherapy for head and neck cancer using a 3-French catheter system: comparison with a 4-French catheter system

PURPOSE

To assess the technical feasibility of transfemoral intra-arterial chemotherapy for head and neck cancer using a 3-French catheter system (3-Fr).

MATERIALS AND METHODS

Sixty-two patients with head and neck cancer who underwent transfemoral intra-arterial chemotherapy were included in this study. Thirty-three patients underwent treatment using a 3-Fr (group 3-Fr). Twenty-nine patients underwent treatment using a 4-French catheter system (group 4-Fr). The technical success rate, duration of the procedure with fluoroscopy, and rate of procedure-related complications were compared between group 3-Fr and group 4-Fr. In addition, in group 3-Fr, bleeding at the puncture site after 1.5 h of bed rest was evaluated.

RESULTS

The technical success rate was 100% in both groups. The duration of the procedure with fluoroscopy didn't differ between group 3-Fr (mean 28.0 min) and group 4-Fr (mean 30.2 min) (p = 0.524). There was no procedure-related complication in either group. In group 3-Fr, no hemorrhagic complication was observed.

CONCLUSION

A 3-French catheter system can be used to perform transfemoral intra-arterial chemotherapy for head and neck cancer and is technically feasible with approximately the same duration of the procedure with fluoroscopy. Furthermore, this method may shorten the bed rest time without hemorrhagic complication, and may reduce the risk of pulmonary embolism.

Traumatic hypovolemic shock revisited: the spectrum of contrast-enhanced abdominal computed tomography findings and clinical implications for its management

Hypovolemic shock is often seen in patients with severe blunt trauma who have suffered from blood circulation inadequate to maintain oxygen delivery to multiple organs. The early recognition and prompt management of hypovolemic shock in patients with multiple injuries are mandatory to improving prognosis and patient conditions. The diagnostic accuracy of computed tomography (CT) as a primary diagnostic tool is well established. The abdominal organs show several common and classic appearances on contrast-enhanced CT in patients with trauma. The hypovolemic shock complex is reported in the previous literature as decreased enhancement of the viscera, increased mucosal enhancement and luminal dilation of the small bowel, mural thickening and fluid-filled loops of the small bowel, the halo sign and flattening of the inferior vena cava, reduced aortic diameter, and peripancreatic edema. However, there have been controversial CT reports with contradictory appearances. Physicians understanding these findings could prompt alternative approaches to the early assessment and management of hypovolemic shock. The aim of this article is to illustrate common and well-known abdominal CT features in patients with traumatic hypovolemic shock, to discuss controversial CT signs in the pancreas and adrenal gland, and to describe CT findings' clinical implications when managing hypovolemic shock.

Measurement of renal cortical thickness using noncontrast-enhanced steady-state free precession MRI with spatially selective inversion recovery pulse: Association with renal function

PURPOSE

To assess whether noncontrast-enhanced steady-state free precession (SSFP) magnetic resonance imaging (MRI) with a spatially selective inversion recovery (IR) pulse can improve the visibility of renal corticomedullary differentiation in patients showing renal dysfunction, and to investigate the correlation between renal cortical thickness and estimated glomerular filtration rate (eGFR).

MATERIALS AND METHODS

Sixty-five patients with and without chronic kidney diseases (CKD) were investigated. Based on eGFR, patients were divided into three groups (Group 1, eGFR < 60; Group 2, eGFR = 60-90; and Group 3, eGFR > 90). All patients underwent noncontrast-enhanced SSFP MRI with spatially selective IR pulses and minimal renal cortical thickness was measured.

RESULTS

The mean corticomedullary contrast ratio was significantly higher in SSFP images with optimal TI than in in-phase images in all three groups (P = 0.001). Positive correlation was seen between the corticomedullary contrast ratio in SSFP images with optimal TI and eGFR (P = 0.011, r = 0.314). A significantly positive correlation was observed between minimal renal cortical thickness and eGFR (P < 0.01, r = 0.495).

CONCLUSION

Noncontrast-enhanced SSFP MRI with a spatially selective IR pulse using optimal TI can improve the visibility of renal corticomedullary differentiation even in patients with renal insufficiency. The decrease in renal cortical thickness measured using this technique correlated significantly with eGFR.

Prognosis of small hepatocellular nodules detected only at the hepatobiliary phase of Gd-EOB-DTPA-enhanced MR imaging as hypointensity in cirrhosis or chronic hepatitis

PURPOSE

To evaluate the prognosis of "strict" high-risk nodules (small hepatocellular nodules detected only in the hepatobiliary phase of initial Gd-EOB-DTPA-enhanced MR examination) in patients with cirrhosis or chronic hepatitis.

METHODS AND MATERIALS

The study included thirty-three patients with 60 "strict" high-risk nodules showing hypointensity at the hepatobiliary phase that was undetectable at the vascular phase and other conventional sequences of initial Gd-EOB-DTPA-enhanced MR imaging. These nodules were observed on follow-up MR examinations until hypervascularity was detected. The potential predictive factors for hypervascular transformation were compared between two groups (group A showing hypervascular transformation, group B not showing hypervascularization).

RESULTS

Ten (16.7 %) of 60 "strict" high-risk nodules showed hypervascular transformation during follow-up periods (group A). The growth rates of the nodules in group A (6.3 ± 4.5 mm/year) were significantly higher than those in group B (3.4 ± 7.2 mm/year) (p = 0.003). Additionally, the median observation period in group A (177.5 ± 189.5 day) was significantly shorter than in group B (419 ± 372.2 day) (p = 0.045). The other predictive factors were not significantly correlated with hypervascularization.

CONCLUSIONS

Subsets of "strict" high-risk nodules showed hypervascular transformation during follow-up periods in association with increased growth rates, indicating that nodule growth rate is an important predictive factor for hypervascularization.

KEY POINTS

• "Strict" high-risk nodules are defined as hepatocellular nodules detected only in the hepatobiliary-phase. • Subsets of "strict" high-risk nodules showed hypervascular transformation during follow-up periods. • Increased growth rate is an important predictive factor for hypervascular transformation. • Management of patients with "strict" high-risk nodules becomes more appropriate.

Renal corticomedullary differentiation by non-contrast-enhanced MR imaging with a spatially selective IR pulse at various inversion times: comparison with fast asymmetric spin echo (FASE) and steady-state free-precession (SSFP)

We compared visualization of corticomedullary differentiation between fast asymmetric spin echo (FASE) and steady-state free precession (SSFP) combined with spatially selective inversion recovery (IR) pulse and optimal inversion time (TI). Though the corticomedullary contrast ratio was higher in FASE than SSFP images, visualization of corticomedullary differentiation was significantly better in SSFP images than FASE images obtained with spatially selective IR pulses and optimal TI.

Assessment of physiologic bile flow in the extrahepatic bile duct with cine-dynamic MR cholangiopancreatography and a spatially selective inversion-recovery pulse

PURPOSE

To determine the feasibility of directly and noninvasively visualizing physiologic bile flow in the extrahepatic bile duct by means of nonpharmacologic cine-dynamic magnetic resonance (MR) cholangiopancreatography with a spatially selective inversion-recovery (IR) pulse and assess the flow dynamic pattern of bile in the extrahepatic bile duct.

MATERIALS AND METHODS

The institutional review board approved this retrospective study and waived the need for informed consent. Thirty-five patients without known pancreatobiliary diseases and 11 patients with dilatation of the extrahepatic bile duct were included. Cine-dynamic MR cholangiopancreatography with a spatially selective IR pulse was performed by imaging every 15 seconds over a 5-minute interval (20 images acquired total). The images were evaluated for the visualization of bile flow, the frequency that bile flow was observed in the extrahepatic bile duct, and the distance the bile moved within the area of the IR pulse. Statistical analysis was performed by using Spearman rank correlation coefficient and Mann-Whitney U tests.

RESULTS

Antegrade bile flow was observed in 29 of 35 patients (83%) in the nondilated group. Bile flow was observed much more frequently in the nondilated group than in the dilated group (4.4 times vs 1.8 times, P = .029). The distance that bile moved forward within the area of the IR pulse was significantly greater in the nondilated group than in the dilated group (mean grade, 0.44 vs 0.14; P = .033), suggesting stagnation or slowdown of antegrade bile flow in patients with biliary dilatation. Reversed bile flow was also observed in 26 of 35 patients (74%) in the nondilated group without biliary diseases.

CONCLUSION

Nonpharmacologic cine-dynamic MR cholangiopancreatography with a spatially selective IR pulse allows direct and noninvasive visualization of bile flow in the extrahepatic bile duct, demonstrating that reversed bile flow is a physiologic phenomenon.

Hypovolemic shock complex: does the pancreatic perfusion increase or decrease at contrast-enhanced dynamic CT?

OBJECTIVE

The purpose of this study is to evaluate contrast enhancement effects of the pancreas at dynamic computed tomography (CT) to clarify whether pancreatic perfusion increases or decreases in severe trauma patients with hypovolemic shock.

METHODS

A total of 90 patients with (n=30) and without (n=60) blunt trauma and hypovolemic shock who underwent dynamic CT for abdomen was included. The measurement of CT attenuation values of the pancreas in the early phase and the late phase was performed to compare the contrast enhancement effects between patients with and without hypovolemic shock.

RESULTS

The mean CT attenuation values of the pancreas in the early phase of dynamic CT in patients with hypovolemic shock [95.4±29.1 Hounsfield units (HU)] were significantly lower (P < .001) than those in non-hypovolemic patients (136.6±17.9 HU), indicating decreased pancreatic perfusion in patients with hypovolemic shock. The mean CT attenuation values of the pancreas in the late phase of dynamic CT in patients with hypovolemic shock (95.9±17.6 HU) were significantly higher (P < .026) than those in non-hypovolemic patients (87.2±9.0 HU), indicating delayed or prolonged pancreatic enhancement in patients with hypovolemic shock.

CONCLUSIONS

Decreased pancreatic perfusion in the early phase and delayed pancreatic enhancement in the late phase of contrast-enhanced dynamic CT was a common finding in patients with hypovolemic shock.

Potential clinical factors affecting hepatobiliary enhancement at Gd-EOB-DTPA-enhanced MR imaging

OBJECTIVE

The objective was to clarify the clinical factors that might affect the degree of hepatic parenchymal enhancement at gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance (MR) imaging.

MATERIALS AND METHODS

A total of 84 patients with (n=63) and without chronic liver disease (n=21) underwent Gd-EOB-DTPA-enhanced MR imaging. Contrast-enhanced MR images of hepatobiliary phase (HP) were obtained at 20 min after Gd-EOB-DTPA administration. The relative enhancement (RE) of liver parenchyma at 20 min HP was calculated from region of interest measurements at each patient. Then, these results were correlated with various clinical parameters using Pearson correlation coefficient or Spearman rank correlation coefficient. Furthermore, the predictor of the degree of hepatic parenchymal enhancement was determined using multiple regression analysis.

RESULTS

The presence or absence of chronic liver disease (P=.002), ascites (P=.005) and splenomegaly (P=.027), and the values of prothrombin activity (P=.008), total bilirubin (T-Bil) (P=.001), albumin (P=.001), aspartate aminotransferase (AST) (P=.002) and cholinesterase (P=.007) were significantly correlated with the RE of liver parenchyma at 20 min HP. Among these parameters, increases of T-Bil (P=.011 to .028) and AST (P=.018 to .049) were predictors of decreased hepatic parenchymal enhancement.

CONCLUSIONS

Hepatic parenchymal enhancement of Gd-EOB-DTPA was affected by various clinical parameters. Impaired hepatobiliary enhancement may be predicted by routine biochemical tests, such as T-Bil and AST.

Peripheral low intensity sign in hepatic hemangioma: diagnostic pitfall in hepatobiliary phase of Gd-EOB-DTPA-enhanced MRI of the liver

PURPOSE

To describe the presence of "peripheral low intensity sign" in hepatic hemangioma in the hepatobiliary phase (HP) of gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) and to compare the frequency of this sign between hepatic hemangiomas and hepatic metastases.

MATERIALS AND METHODS

The Institutional Review Board approved this study and waived the requirement for informed consent. Sixty-four patients with 51 hepatic hemangiomas (n = 31 patients) and with 58 hepatic metastases (n = 33 patients) underwent Gd-EOB-DTPA-enhanced MRI. In all hepatic hemangiomas, 41 lesions were the typical type and 10 were the high flow type. HP images were qualitatively evaluated for the frequency of peripheral low intensity sign in hepatic hemangiomas and hepatic metastases using a four-point scale. Statistical evaluations were performed with a Mann-Whitney U-test.

RESULTS

Peripheral low intensity signs were demonstrated in 24 (47%) of 51 hepatic hemangiomas, while they were seen in 27 (47%) of 58 hepatic metastases. There was no significant difference in the mean visual score of peripheral low intensity sign between all hepatic hemangiomas (0.84 ± 1.03) and hepatic metastases (0.76 ± 0.92). The mean visual score of peripheral low intensity sign in typical hemangiomas (1.02 ± 1.06) was significantly higher than that in high flow hemangiomas (0.10 ± 0.32) (P = 0.008).

CONCLUSION

Peripheral low intensity sign is not specific for malignant tumors, and can be seen even in hepatic hemangiomas on HP of Gd-EOB-DTPA-enhanced MRI.

Age-related changes in normal adult pancreas: MR imaging evaluation

OBJECTIVE

To investigate age-related changes in normal adult pancreas as identified by magnetic resonance imaging (MRI).

MATERIALS AND METHODS

We examined 115 patients without pancreatic diseases (21-90 years) who underwent upper abdominal MRI to evaluate the normal pancreatic MRI findings related to aging. The parameters examined were the pancreatic anteroposterior (AP) diameter, pancreatic lobulation, pancreatic signal intensity (SI), depiction of the main pancreatic duct (MPD), grade of the visual SI decrease on the opposed-phase T1-weighted images compared with in-phase images, and enhancement effect of the pancreas in the arterial phase of dynamic imaging.

RESULTS

The pancreatic AP diameter significantly reduced (head, p=0.0172; body, p=0.0007; tail, p<0.0001), and lobulation (p<0.0001) and parenchymal fatty change (p<0.0001) became more evident with aging. No significant correlation was observed between aging and pancreatic SI, however the SI on the in-phase T1-weighted images tended to decrease with aging. No significant correlation was observed between aging and the depiction of the MPD as well as aging and contrast enhancement.

CONCLUSION

MRI findings of pancreatic atrophy, lobulation, and fatty degeneration are characteristic changes related to aging, and it is necessary to recognize these changes in the interpretation of abdominal MRI in patients with and without pancreatic disease.

Gd-EOB-DTPA-enhanced MR imaging: evaluation of hepatic enhancement effects in normal and cirrhotic livers

OBJECTIVE

The purpose of this study was to assess differences in enhancement effects of liver parenchyma between normal and cirrhotic livers on contrast-enhanced MR imaging (CE-MRI) obtained with Gd-EOB-DTPA.

METHODS

A total of 99 patients with cirrhotic liver (n=58; Child-Pugh class A, n=30; B, n=22; C, n=6) and normal liver (n=41) underwent Gd-EOB-DTPA-enhanced MR imaging. CE images were obtained before contrast injection, in the arterial phase (AP) at 25s or modified scan delay, in the portal phase (PP) at 70s, in the equilibrium phase (EP) at 3 min, and in the hepatobiliary phase (HP) at 3 times (10, 15 and 20 min). Signal intensity of the liver in all phases was defined using region-of-interest measurements for relative enhancement (RE) calculation.

RESULTS

In normal-liver and Child-Pugh class A and B patients, mean RE of liver parenchyma increased significantly (P<0.03-0.001) with time until 20-min HP. Conversely, mean RE for Child-Pugh class C patients did not show any increasing tendency after PP. Mean RE of liver parenchyma at EP and HP (10-, 15- and 20-min) was highest in normal liver, followed by Child-Pugh class A, B and C cirrhosis (P<0.02-0.001).

CONCLUSION

Hepatic parenchymal enhancement on CE-MR images obtained using Gd-EOB-DTPA is affected by the severity of cirrhosis.