MR elastography of the liver at 3.0 T in diagnosing liver fibrosis grades; preliminary clinical experience

Objectives

To clarify the usefulness of 3.0-T MR elastography (MRE) in diagnosing the histological grades of liver fibrosis using preliminary clinical data.

Materials and methods

Between November 2012 and March 2014, MRE was applied to all patients who underwent liver MR study at a 3.0-T clinical unit. Among them, those who had pathological evaluation of liver tissue within 3 months from MR examinations were retrospectively recruited, and the liver stiffness measured by MRE was correlated with histological results. Institutional review board approved this study, waiving informed consent.

Results

There were 70 patients who met the inclusion criteria. Liver stiffness showed significant correlation with the pathological grades of liver fibrosis (rho?=?0.89, p?<?0.0001, Spearman’s rank correlation). Areas under the receiver operating characteristic curve were 0.93, 0.95, 0.99 and 0.95 for fibrosis score greater than or equal to F1, F2, F3 and F4, with cut-off values of 3.13, 3.85, 4.28 and 5.38 kPa, respectively. Multivariate analysis suggested that grades of necroinflammation also affected liver stiffness, but to a significantly lesser degree as compared to fibrosis.

Conclusions

3.0-T clinical MRE was suggested to be sufficiently useful in assessing the grades of liver fibrosis.

Key Points

? MR elastography may help clinicians assess patients with chronic liver diseases ? Usefulness of 3.0-T MR elastography has rarely been reported ? Measured liver stiffness correlated well with the histological grades of liver fibrosis ? Measured liver stiffness was also affected by necroinflammation, but to a lesser degree ? 3.0-T MRE could be a non-invasive alternative to liver biopsy

     

Assessment of fibrotic tissue and microvascular architecture by in-line phase-contrast imaging in a mouse model of liver fibrosis

Purpose

To explore the value of in-line phase-contrast imaging with computed tomography (ILPCI-CT) by synchrotron radiation (SR) for liver fibrosis.

Materials and methods

Liver fibrosis models were set up in 13 BALB/c mice by peritoneal injections of thioacetamide and evaluated by ILPCI-CT. Histological staging was used to categorize liver fibrosis into normal, mild fibrosis and advanced fibrosis groups. Microvessel density (MVD), the ratio of total vessel length to volume (L/V), the ratio of total number of branching points to liver volume (P/V) and the distribution of vessel diameter were assessed.

Results

The CT images showed slightly high-density shadows around the portal tracts in the fibrosis group. Three-dimensional reconstruction can detect vascular and nodular changes on the surface of fibrotic livers. The MVDs between the three groups were significantly different (P?=?0.024). L/V was significantly different between the three groups (P?=?0.014). There was a positive correlation between MVD and P/V.

Conclusion

Fibrous material can be detected by ILPCI-CT even in the early stage of fibrosis. MVD, L/V, P/V and the distribution of vessel diameter were consistent with fibrosis-related angiogenesis progress. Three-dimensional reconstruction is a promising method to visualize morphological changes of the fibrotic liver.

Key Points

? ILPCI-CT can detect fibrous material even in the early stage of liver fibrosis. ? MVD, L/V, P/V, and the distribution of vascular diameter reflect pathological angiogenesis. ? 3D reconstruction could be a promising approach for detecting liver fibrosis.

     

Gadoxetic acid-enhanced magnetic resonance imaging characteristics of hepatocellular carcinoma occurring in liver transplants

Objectives

Characteristics of hepatocellular carcinoma (HCC) on magnetic resonance (MR) images were compared in patients who did or did not undergo liver transplantation (LT), and we evaluated the relationship of these findings with overall survival (OS) and time-to-tumour recurrence (TTR) after transplantation.

Methods

The enhancement pattern of gadoxetic acid-enhanced MR images of 25 patients with recurrent HCCs (LT group) and 25 surgically confirmed HCC patients in the non-transplanted (control) group were compared. Typical enhancement was defined as 1) arterial enhancement and delayed wash-out and 2) absence of typical features of cholangiocarcinoma consisting of arterial rim enhancement and target appearance on hepatobiliary phase images. OS and TTR were analyzed in the LT group according to these patterns using the log-rank test.

Results

HCCs in the LT group significantly more often had an atypical enhancement pattern (16/25, 64.0%) than those in the control group (5/25, 20.0%; p = 0.004). However, OS and TTR did not differ significantly according to these enhancement patterns of recurrent HCC (p > 0.05).

Conclusion

Although enhancement patterns of recurrent HCC in transplanted liver did not affect OS and TTR, these HCCs that arise after LT frequently revealed atypical enhancement on gadoxetic acid-enhanced MR imaging.

Key Points

? Recurrent HCCs after LT showed atypical enhancement on gadoxetic acid-enhanced MRI.?They showed absence of delayed wash-out or cholangiocarinoma-like features.? Enhancement patterns of recurrent HCCs did not affect OS and TTR.

     

Inter-sonographer reproducibility of quantitative ultrasound outcomes and shear wave speed measured in the right lobe of the liver in adults with known or suspected non-alcoholic fatty liver disease

Objectives

To assess inter-sonographer reproducibility of ultrasound attenuation coefficient (AC), backscatter coefficient (BSC) and shear wave speed (SWS) in adults with known/suspected non-alcoholic fatty liver disease (NAFLD).

Methods

The institutional review board approved this HIPAA-compliant prospective study; informed consent was obtained. Participants with known/suspected NAFLD were recruited and underwent same-day liver examinations with a clinical scanner. Each participant was scanned by two of the six trained sonographers. Each sonographer performed multiple data acquisitions in the right liver lobe using a lateral intercostal approach. A data acquisition was a single operator button press that recorded a B-mode image, radio-frequency data, and the SWS value. AC and BSC were calculated from the radio-frequency data using the reference phantom method. SWS was calculated automatically using product software. Intraclass correlation coefficient (ICC) and within-subject coefficient of variation (wCV) were calculated for applicable metrics.

Results

Sixty-one participants were recruited. Inter-sonographer ICC was 0.86 (95% confidence interval: 0.77–0.92) for AC and 0.87 (0.78–0.92) for log-transformed BSC (logBSC?=?10log₁₀BSC) using one acquisition per sonographer. ICC was 0.88 (0.80–0.93) for both AC and logBSC averaging 5 acquisitions. ICC for SWS was 0.57 (0.29–0.74) using one acquisition per sonographer, and 0.84 (0.66–0.93) using 10 acquisitions. The wCV was ~7% for AC, and 19–43% for SWS, depending on number of acquisitions.

Conclusions

Hepatic AC, BSC and SWS measures on a clinical scanner have good inter-sonographer reproducibility in adults with known or suspected NAFLD. Multiple acquisitions are required for SWS but not AC or BSC to achieve good inter-sonographer reproducibility.

Key Points

? AC, BSC and SWS measurements are reproducible in adults with NAFLD. ? Inter-sonographer reproducibility of SWS measurement improves with more acquisitions being averaged. ? Multiple acquisitions are required for SWS but not AC or BSC.

     

Gadoxetic acid disodium-enhanced MR imaging of cholangiolocellular carcinoma of the liver: imaging characteristics and histopathological correlations

Objectives

To review the gadoxetic acid disodium (EOB)-enhanced magnetic resonance (MR) imaging features of cholangiolocellular carcinoma (CoCC) of the liver and compare them with those of hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC).

Methods

EOB-enhanced MR images of 19 patients with CoCC, 23 with ICC, and 51 with HCC were retrospectively evaluated qualitatively and quantitatively. Univariate and multivariate analyses were performed to determine the characteristic MR features of CoCC with histopathological–imaging correlation.

Results

Multivariate logistic regression analysis showed that dot-/band-shaped internal enhancement during the arterial and portal phases (P?<?0.001), and larger arterial ring enhancement ratio (CoCC, 0.13?±?0.04; ICC, 0.074?±?0.04; P?=?0.013) were significantly independently associated with CoCC in contrast to ICC, whereas several MR features including progressive enhancement during the portal and late phases (P?<?0.001), target appearance in the hepatocyte phase (P?=?0.004), and vessel penetration (P?=?0.013) were significantly more frequently associated with CoCC than HCC. The dot-/band-like internal enhancement (78.9% of CoCCs) histopathologically corresponded to the tumour cell nest with vascular proliferations and retained Glisson's sheath structure.

Conclusions

EOB-enhanced MR features of CoCC largely differ from those of HCC but are similar to those of ICC. However, the finding of thicker arterial ring enhancement with dot-/band-like internal enhancement could help differentiate CoCC from ICC.

Key Points

? Gadoxetic acid-enhanced MR features of cholangiolocellular carcinoma (CoCC) resembled those of intrahepatic cholangiocarcinoma (ICC).? Gadoxetic acid-enhanced MR features of CoCC largely differed from those of hepatocellular carcinoma.? Dot-/band-like internal enhancement of CoCC may be helpful for differentiating from ICC.? Arterial ring enhancement of CoCC was larger than that of ICC.

     

Globus pallidus MR signal abnormalities in children with chronic liver disease and/or porto-systemic shunting

Objectives

Detection of subclinical hepatic encephalopathy in children is difficult. We aimed to assess the changes in imaging of the central nervous system in children with chronic liver disease using MR imaging, diffusion, and ¹H -spectroscopy.

Methods

Forty three children with chronic liver disease and/or porto-systemic shunting (111.4±56.9 months) and 24 controls (72.0±51.8 months) underwent brain MRI/spectroscopy on a 1.5T to examine T1, T2, ADC, Cho/Cr, ml/Cr, Glx/Cr ratio spectroscopy in the globus pallidus. Patients were divided into 3 groups according to the ratios of globus pallidus/putamen T1 signal : isointense (i), hyperintense (h), much more hyperintense (h+). The relationship with clinical and biological data was analyzed.

Results

T1 signal intensity and ml/Cr were significantly different between controls and group h+ (p=0.001). ADC did not differ significantly between groups. Age correlated strongly with the presence of a T1 signal ratio (p > 0.001). There was no correlation between imaging findings and biological parameters.

Conclusions

In children with chronic liver disease and/or porto-systemic shunting, the presence of a hyperintense T1 signal in the globus pallidus correlated strongly with age. Biological and clinical parameters were not predictive of these changes. MRI may become a useful screening tool for hepatic encephalopathy in children.

Key Points

? Children with chronic liver disease should undergo brain MRI during their follow-up ? T1 hyperintensity of globus pallidus is suggestive of liver-related CNS involvement ? MRS mI/Cr is decreased in children with chronic liver disease ? Biological parameters (ammonium) were not predictive of hepatic encephalopathy ? Duration of chronic liver disease may be causative the hepatic encephalopathy

     

Abdominal fat volume estimation by stereology on CT: a comparison with manual planimetry

Objectives

To deploy and evaluate a stereological point-counting technique on abdominal CT for the estimation of visceral (VAF) and subcutaneous abdominal fat (SAF) volumes.

Methods

Stereological volume estimations based on point counting and systematic sampling were performed on images from 14 consecutive patients who had undergone abdominal CT. For the optimization of the method, five sampling intensities in combination with 100 and 200 points were tested. The optimum stereological measurements were compared with VAF and SAF volumes derived by the standard technique of manual planimetry on the same scans.

Results

Optimization analysis showed that the selection of 200 points along with the sampling intensity 1/8 provided efficient volume estimations in less than 4 min for VAF and SAF together. The optimized stereology showed strong correlation with planimetry (VAF: r?=?0.98; SAF: r?=?0.98). No statistical differences were found between the two methods (VAF: P?=?0.81; SAF: P?=?0.83). The 95 % limits of agreement were also acceptable (VAF: ?16.5 %, 16.1 %; SAF: ?10.8 %, 10.7 %) and the repeatability of stereology was good (VAF: CV?=?4.5 %, SAF: CV?=?3.2 %).

Conclusions

Stereology may be successfully applied to CT images for the efficient estimation of abdominal fat volume and may constitute a good alternative to the conventional planimetric technique.

Key Points:

? Abdominal obesity is associated with increased risk of disease and mortality. ? Stereology may quantify visceral and subcutaneous abdominal fat accurately and consistently. ? The application of stereology to estimating abdominal volume fat reduces processing time. ? Stereology is an efficient alternative method for estimating abdominal fat volume.

     

Detection of pulmonary fat embolism with dual-energy CT: an experimental study in rabbits

Objectives

To evaluate the use of dual-energy CT imaging of the lung perfused blood volume (PBV) for the detection of pulmonary fat embolism (PFE).

Methods

Dual-energy CT was performed in 24 rabbits before and 1 hour, 1 day, 4 days and 7 days after artificial induction of PFE via the right ear vein. CT pulmonary angiography (CTPA) and lung PBV images were evaluated by two radiologists, who recorded the presence, number, and location of PFE on a per-lobe basis. Sensitivity, specificity, and accuracy of CTPA and lung PBV for detecting PFE were calculated using histopathological evaluation as the reference standard.

Results

A total of 144 lung lobes in 24 rabbits were evaluated and 70 fat emboli were detected on histopathological analysis. The overall sensitivity, specificity and accuracy were 25.4 %, 98.6 %, and 62.5 % for CTPA, and 82.6 %, 76.0 %, and 79.2 % for lung PBV. Higher sensitivity (p?<?0.001) and accuracy (p?<?0.01), but lower specificity (p?<?0.001), were found for lung PBV compared with CTPA. Dual-energy CT can detect PFE earlier than CTPA (all p?<?0.01).

Conclusion

Dual-energy CT provided higher sensitivity and accuracy in the detection of PFE as well as earlier detection compared with conventional CTPA in this animal model study.

Key points

? Fat embolism occurs commonly in patients with traumatic bone injury.? Dual-energy CT improves diagnostic performance for pulmonary fat embolism detection.? Dual-energy CT can detect pulmonary fat embolism earlier than CTPA.

     

Gd-EOB-DTPA-enhanced T1 relaxometry for assessment of liver function determined by real-time <Superscript>13</Superscript>C-methacetin breath test

Objectives

To determine whether liver function as determined by intravenous administration of ¹³C-methacetin and continuous real-time breath analysis can be estimated quantitatively from gadoxetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance (MR) relaxometry.

Methods

Sixty-six patients underwent a ¹³C-methacetin breath test (¹³C-MBT) for evaluation of liver function and Gd-EOB-DTPA-enhanced T1-relaxometry at 3 T. A transverse 3D VIBE sequence with an inline T1 calculation based on variable flip angles was acquired prior to (T1 pre) and 20 min post-Gd-EOB-DTPA (T1 post) administration. The reduction rate of T1 relaxation time (rrT1) and T1 relaxation velocity index (?R1) between pre- and post-contrast images was evaluated. ¹³C-MBT values were correlated with T1_post, ?R1 and rrT1, providing an MRI-based estimated ¹³C-MBT value. The interobserver reliability was assessed by determining the intraclass correlation coefficient (ICC).

Results

Stratified by three different categories of ¹³C-MBT readouts, there was a constant increase of T1 post with increasing progression of diminished liver function (p ≤ 0.030) and a constant significant decrease of ?R1 (p ≤ 0.025) and rrT1 (p < 0.018) with progression of liver damage as assessed by ¹³C-methacetin breath analysis. ICC for all T1 relaxation values and indices was excellent (> 0.88). A simple regression model showed a log-linear correlation of ¹³C-MBT values with T1_post (r = 0.57; p < 0.001), ?R1 (r = 0.59; p < 0.001) and rrT1 (r = 0.70; p < 0.001).

Conclusion

Liver function as determined using real-time ¹³C-methacetin breath analysis can be estimated quantitatively from Gd-EOB-DTPA-enhanced MR relaxometry.

Key Points

? Gd-EOB-DTPA-enhanced T1 relaxometry quantifies liver function? Gd-EOB-DTPA-enhanced MR relaxometry may provide parameters for assessing liver function before surgery? Gd-EOB-DTPA-enhanced MR relaxometry may be useful for monitoring liver disease progression? Gd-EOB-DTPA-enhanced MR relaxometry has the potential to become a novel liver function index

     

Chronic hepatitis B: correlation of abnormal features on T2-weighted imaging and dynamic contrast-enhanced imaging with hepatic histopathology

Objectives

To investigate the correlations between abnormal features on liver magnetic resonance (MR) T2-weighted imaging (T2WI) and dynamic contrast-enhanced (DCE) imaging and the pathological findings in chronic hepatitis B.

Materials and methods

Sixty-seven patients with chronic hepatitis B and 18 normal controls who were undergone an abdominal MR imaging were analyzed retrospectively. Patchy hyperintensities, linear and reticular hyperintensities in liver and periportal edema on T2WI and abnormal intrahepatic enhancement signals on DCE imaging were noted. The correlations between the abnormal features detected on hepatic T2WI and DCE imaging, and the levels of inflammatory activity and fibrosis were determined.

Results

Logistic regression analysis showed increased patchy hyperintensities (B = 1.869, P = 0.001) on T2WI and patchy enhancement (B = 1.596, P = 0.004) at the arterial phase along with increased inflammatory activity. However, linear and reticular hyperintensities (B = 2.356, P = 0.000) on T2WI, and meshwork enhancement (B = 2.191, P = 0.000) at the equilibrium phase, all correlated with fibrosis. Moreover, periportal edema mainly correlated with the inflammatory activities (B = 2.635, P = 0.001).

Conclusions

In chronic hepatitis B patients, patchy hyperintensities on T2WI, periportal edema, and patchy enhancement at the arterial phase can predict moderate-to-severe inflammatory activities, whereas intrahepatic linear and reticular hyperintensities on T2WI, and meshwork enhancement at the equilibrium phase can predict moderate-to-severe fibrosis.

     

Navigated MRI-guided liver biopsies in a closed-bore scanner: experience in 52 patients

Objectives

To evaluate clinical effectiveness and diagnostic efficiency of a navigation device for MR-guided biopsies of focal liver lesions in a closed-bore scanner.

Methods

In 52 patients, 55 biopsies were performed. An add-on MR navigation system with optical instrument tracking was used for image guidance and biopsy device insertion outside the bore. Fast control imaging allowed visualization of the true needle position at any time. The biopsy workflow and procedure duration were recorded. Histological analysis and clinical course/outcome were used to calculate sensitivity, specificity and diagnostic accuracy.

Results

Fifty-four of 55 liver biopsies were performed successfully with the system. No major and four minor complications occurred. Mean tumour size was 23?±?14 mm and the skin-to-target length ranged from 22 to 177 mm. In 39 cases, access path was double oblique. Sensitivity, specificity and diagnostic accuracy were 88 %, 100 % and 92 %, respectively. The mean procedure time was 51?±?12 min, whereas the puncture itself lasted 16?±?6 min. On average, four control scans were taken.

Conclusions

Using this navigation device, biopsies of poorly visible and difficult accessible liver lesions could be performed safely and reliably in a closed-bore MRI scanner. The system can be easily implemented in clinical routine workflow.

Key Points

? Targeted liver biopsies could be reliably performed in a closed-bore MRI. ? The navigation system allows for image guidance outside of the scanner bore. ? Assisted MRI-guided biopsies are helpful for focal lesions with a difficult access. ? Successful integration of the method in clinical workflow was shown. ? Subsequent system installation in an existing MRI environment is feasible.

     

Preoperative staging of non-small cell lung cancer: prospective comparison of PET/MR and PET/CT

Objectives

To prospectively compare the accuracies of PET/MR and PET/CT in the preoperative staging of non-small cell lung cancer (NSCLC).

Methods

Institutional review board approval and patients’ informed consents were obtained. 45 patients with proven or radiologically suspected lung cancer which appeared to be resectable on CT were enrolled. PET/MR was performed for the preoperative staging of NSCLC followed by PET/CT without contrast enhancement on the same day. Dedicated MR images including diffusion weighted images were obtained. Readers assessed PET/MR and PET/CT with contrast-enhanced CT. Accuracies of PET/MR and PET/CT for NSCLC staging were compared.

Results

Primary tumour stages (n?=?40) were correctly diagnosed in 32 patients (80.0 %) on PET/MR and in 32 patients (80.0 %) on PET/CT (P?=?1.0). Node stages (n?=?42) were correctly determined in 24 patients (57.1 %) on PET/MR and in 22 patients (52.4 %) on PET/CT (P?=?0.683). Metastatic lesions in the brain, bone, liver, and pleura were detected in 6 patients (13.3 %). PET/MR missed one patient with pleural metastasis while PET/CT missed one patient with solitary brain metastasis and two patients with pleural metastases (P?=?0.480).

Conclusions

This study demonstrated that PET/MR in combination with contrast-enhanced CT was comparable to PET/CT in the preoperative staging of NSCLC while reducing radiation exposure.

Key points

? PET/MR can be comparable to PET/CT for preoperative NSCLC staging.? PET/MR and PET/CT show excellent correlation in measuring SUVmax of primary lesions.? Using PET/MR, estimated radiation dose can decrease by 31.1?% compared with PET/CT.

     

Usefulness of IDEAL T2-weighted FSE and SPGR imaging in reducing metallic artifacts in the postoperative ankles with metallic hardware

Purpose

The aim of this work is to prospectively compare the effectiveness of iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL), T2-weighted fast spin-echo (FSE), and spoiled gradient-echo (SPGR) MR imaging to frequency selective fat suppression (FSFS) protocols for minimizing metallic artifacts in postoperative ankles with metallic hardware.

Materials and methods

The T2-weighted and SPGR imaging with IDEAL and FSFS were performed on 21 ankles of 21 patients with metallic hardware. Two musculoskeletal radiologists independently analyzed techniques for visualization of ankle ligaments and articular cartilage, uniformity of fat saturation, and relative size of the metallic artifacts. A paired t test was used for statistical comparisons of MR images between IDEAL and FSFS groups.

Results

IDEAL T2-weighted FSE and SPGR images enabled significantly improved visualization of articular cartilage (p?<?0.05), the size of metallic artifact (p?<?0.05), and the uniformity of fat saturation (p?<?0.05). However, no significant improvement was found in the visibility of ligaments.

Conclusions

IDEAL T2-weighted FSE and SPGR imaging effectively reduces the degree of tissue-obscuring artifacts produced by fixation hardware in ankle joints and improves image quality compared to FSFS T2-weighted FSE and SPGR imaging. However, visibility of ligaments was not improved using IDEAL imaging.

     

Acute downhill running does not induce fat oxidation

Objectives

Eccentric exercise has been suggested for its potential to increase several health outcomes, including exercise-induced fat oxidation. Comparison of exercise intensity rather than exercise workload is required.

Methods

Thirteen moderately active young men (mean age, 24.6 ± 5.6 years; body mass index, 23.76 ± 3.24 kg/m²; maximal oxygen consumption (VO_2max), 49.00 ± 3.19 ml/kg/min) performed two counterbalanced running sessions for 40 min at 60% VO_2max, either running flat (Con-Exe) or running downhill at a gradient of ? 12% (Ecc-Exe). The volumes of oxygen and carbon dioxide (VO₂ and VCO₂) were collected during exercise sessions, and fat oxidation was calculated.

Results

There was no significant interaction between exercise condition and exercise duration (p > 0.05), and individual variations in fat oxidation during Con-Exe and Ecc-Exe were large and inconsistent.

Conclusion

Downhill running at 60% VO_2max and inclination of ? 12% does not induce fat oxidation.

     

CT texture features of liver parenchyma for predicting development of metastatic disease and overall survival in patients with colorectal cancer

Objectives

To determine if identifiable hepatic textural features are present at abdominal CT in patients with colorectal cancer (CRC) prior to the development of CT-detectable hepatic metastases.

Methods

Four filtration–histogram texture features (standard deviation, skewness, entropy and kurtosis) were extracted from the liver parenchyma on portal venous phase CT images at staging and post-treatment surveillance. Surveillance scans corresponded to the last scan prior to the development of CT-detectable CRC liver metastases in 29 patients (median time interval, 6 months), and these were compared with interval-matched surveillance scans in 60 CRC patients who did not develop liver metastases. Predictive models of liver metastasis-free survival and overall survival were built using regularised Cox proportional hazards regression.

Results

Texture features did not significantly differ between cases and controls. For Cox models using all features as predictors, all coefficients were shrunk to zero, suggesting no association between any CT texture features and outcomes. Prognostic indices derived from entropy features at surveillance CT incorrectly classified patients into risk groups for future liver metastases (p < 0.001).

Conclusions

On surveillance CT scans immediately prior to the development of CRC liver metastases, we found no evidence suggesting that changes in identifiable hepatic texture features were predictive of their development.

Key Points

? No correlation between liver texture features and metastasis-free survival was observed. ? Liver texture features incorrectly classified patients into risk groups for liver metastases. ? Standardised texture analysis workflows need to be developed to improve research reproducibility.

     

Hypervascular solid-appearing serous cystic neoplasms of the pancreas: Differential diagnosis with neuroendocrine tumours

Purpose

To describe imaging findings of arterial hypervascular solid-appearing serous cystic neoplasms (SCNs) of the pancreas on CT and MR and determine imaging features differentiating them from neuroendocrine tumours (NETs).

Materials and methods

We retrospectively identified 15 arterial hypervascular solid-appearing SCNs and randomly chose 30 size-matched pancreatic NETs. On CT, two radiologists in consensus assessed the size, morphology, and CT attenuation. On MR, predominant signal intensity and the amount of the cystic component on T2-weighted images and ADC maps were evaluated and compared using Fisher’s exact and Student’s t-test.

Results

The mean SCN size was 2.6 cm (range, 0.8–8.3). The CT findings were similar between the two tumours: location, shape, margin, and enhancement pattern. SCNs were significantly more hypodense on non-enhanced CT images than NETs (P?=?.03). They differed significantly on MR: bright signal intensity (P?=?.01) and more than a 10 % cystic component on T2-weighted images (P?=?.01) were more common in SCNs than in NETs. All SCNs showed a non-restrictive pattern on the ADC map, while NETs showed diffusion restriction (P?<?.01).

Conclusion

Arterial hypervascular solid-appearing SCNs and NETs share similar imaging features. Non-enhanced CT and MR images with T2-weighted images and ADC maps can facilitate the differentiation.

Key points

? Frequency of hypervascular solid-appearing SCNs was 7.3?% among surgically confirmed SCNs.? Hypervascular solid-appearing SCN of the pancreas can mimic pancreatic NETs.? Unenhanced CT and MR features help to differentiate the two tumours.

     

Dynamic multidetector CT and non-contrast-enhanced MR for right adrenal vein imaging: comparison with catheter venography in adrenal venous sampling

Objectives

To evaluate visualization of the right adrenal vein (RAV) with multidetector CT and non-contrast-enhanced MR imaging in patients with primary aldosteronism.

Methods

A total of 125 patients (67 men) scheduled for adrenal venous sampling (AVS) were included. Dynamic 64-detector-row CT and balanced steady-state free precession-based non-contrast-enhanced 3-T MR imaging were performed. RAV visualization based on a four-point score was documented. Both anatomical location and variation on cross-sectional imaging were evaluated, and the findings were compared with catheter venography as the gold standard.

Results

The RAV was visualized in 93.2 % by CT and 84.8 % by MR imaging (p?=?0.02). Positive predictive values of RAV visualization were 100 % for CT and 95.2 % for MR imaging. Imaging score was significantly higher in CT than MR imaging (p?<?0.01). The RAV formed a common trunk with an accessory hepatic vein in 16 % of patients. The RAV orifice level on cross-sectional imaging was concordant with catheter venography within the range of 1/3 vertebral height in >70 % of subjects. Success rate of AVS was 99.2 %.

Conclusions

Dynamic CT is a reliable way to map the RAV prior to AVS. Non-contrast-enhanced MR imaging is an alternative when there is a risk of complication from contrast media or radiation exposure.

Key Points

? Dynamic CT and non-contrast-enhanced MR imaging detect the right adrenal vein (RAV). ? Dynamic CT can visualize the RAV more than non-contrast-enhanced MR imaging. ? Mapping the RAV helps to achieve successful adrenal venous sampling. ? Sixteen per cent of RAVs share the common trunk with accessory hepatic veins.

     

Can MR textural analysis improve the prediction of extracapsular nodal spread in patients with oral cavity cancer?

Objective

To explore the utility of MR texture analysis (MRTA) for detection of nodal extracapsular spread (ECS) in oral cavity squamous cell carcinoma (SCC).

Methods

115 patients with oral cavity SCC treated with surgery and adjuvant (chemo)radiotherapy were identified retrospectively. First-order texture parameters (entropy, skewness and kurtosis) were extracted from tumour and nodal regions of interest (ROIs) using proprietary software (TexRAD). Nodal MR features associated with ECS (flare sign, irregular capsular contour; local infiltration; nodal necrosis) were reviewed and agreed in consensus by two experienced radiologists. Diagnostic performance characteristics of MR features of ECS were compared with primary tumour and nodal MRTA prediction using histology as the gold standard. Receiver operating characteristic (ROC) and regression analyses were also performed.

Results

Nodal entropy derived from contrast-enhanced T1-weighted images was significant in predicting ECS (p?=?0.018). MR features had varying accuracy: flare sign (70%); irregular contour (71%); local infiltration (66%); and nodal necrosis (64%). Nodal entropy combined with irregular contour was the best predictor of ECS (p?=?0.004, accuracy 79%).

Conclusion

First-order nodal MRTA combined with imaging features may improve ECS prediction in oral cavity SCC.

Key Points

? Nodal MR textural analysis can aid in predicting extracapsular spread (ECS). ? Medium filter contrast-enhanced T1 nodal entropy was strongly significant in predicting ECS. ? Combining nodal entropy with irregular nodal contour improves predictive accuracy.

     

Brain-core temperature of patients before and after orthotopic liver transplantation assessed by DWI thermometry

Purpose

To assess brain-core temperature of end-stage liver disease patients undergoing orthotopic liver transplantation (OLT) using a temperature measurement technique based on the apparent diffusion coefficient of the cerebrospinal fluid in the lateral ventricles.

Materials and methods

The study group was composed of 19 patients with a model for end-stage liver disease (MELD) score of 23.7 who underwent MR imaging before and after OLT. MR imaging studies were performed with a 1.5T MR scanner. Brain-core temperature (T: °C) was calculated using the following equation from the apparent diffusion coefficient (D) of the cerebrospinal fluid in the lateral ventricles: \(T = {{2256.74} \mathord{\left/ {\vphantom {{2256.74} {\ln \left( {4.39221/D} \right)}}} \right. \kern-0pt} {\ln \left( {4.39221/D} \right)}}{-}273.15\) measured with a DWI sequence (b value 1000 s/mm²). We compared brain-core temperature of all patients before and after OLT.

Results

Brain-core temperature measurements were successfully taken in all patients before and after OLT. The measured brain-core temperature mean?±?standard deviation was 38.67?±?1.76 °C before OLT and 38.60?±?0.99 °C after OLT, showing no significant difference (P = 0.643).

Conclusions

Brain-core temperature was stable in patients undergoing OLT. DWI thermometry may provide a supplementary brain biomarker to confirm that cerebral blood flow and metabolism are stable in patients undergoing OLT.