Pancreatic MRI for the surveillance of cystic neoplasms: comparison of a short with a comprehensive imaging protocol

Objectives

The study aims were to evaluate: (1) whether a short-protocol (SP) MRI for the surveillance of pancreatic cystic neoplasms (PCN) provides equivalent clinical information as a comprehensive-protocol (CP), and (2) the cost reduction from substituting CP with SP for patient surveillance.

Methods

This retrospective study included 154 consecutive patients (median age: 66, 52 % men) with working-diagnosis of PCN and available contrast-enhanced MRI/MRCP. Three radiologists evaluated independently two imaging sets (SP/CP) per patient. The CP included: T2-weighted (HASTE/MRCP), DWI and T1-weighted (chemical-shift/pre-/post-contrast) images [acquisition time (AT)?≈?35 min], whereas the SP included: T2-weighted HASTE and T1-weighted pre-contrast images (AT?≈?8 min). Mean values of largest cyst/main pancreatic duct diameter (D_C/D_MPD) were compared. Agreement regarding presence/absence of cystic/MPD mural nodules (MN_C/MN_MPD), inter-observer agreement and cost differences between SP/CP were calculated.

Results

For D_C and D_MPD, mean values with SP/CP were 21.4/21.7 mm and 3.52/3.58 mm, while mean differences SP-CP were 0.3 mm (p?=?0.02) and 0.06 mm (p?=?0.12), respectively. For presence/absence of MN_C and MN_MPD, SP/CP coincided in 93 % and 98 % of cases, respectively. Inter-observer agreement was strong for SP/CP. SP-cost was 25 % of CP-cost.

Conclusions

For the surveillance of PCN, short-protocol MRI provides information equivalent to the more time-consuming and costly comprehensive-protocol.

Key Points

? Pancreatic cystic neoplasms (PCN) are increasingly diagnosed in the general population. ? Multiple imaging controls are recommended for the surveillance of patients with PCN. ? Short and comprehensive MRI-protocols are equivalent for decision-making in PCN under surveillance. ? Evaluation of imaging risk factors in PCNs is comparable with both MRI-protocols. ? Use of the short MRI-protocol may rationalise healthcare resources.

     

Accuracy of early CT findings for predicting disease course in patients with acute pancreatitis

Purpose

To investigate whether computed tomography (CT)-based scoring systems obtained within 72 h of symptoms onset can predict disease course in acute pancreatitis.

Methods

Between October 2007 and December 2015, 189 patients (age range 21–93 years) who underwent abdominopelvic CT for the diagnosis of acute pancreatitis were included in the study. Balthazar grade and original and modified versions of CT severity index (CTSI) measurements were carried out for each patient.

Results

There were significant associations between each CT based scoring system and development of pancreatic and extrapancreatic complications (p < 0.001). A cutoff value of > 6 for CTSI and > 9 for the modified version of CTSI achieved a specificity of 98.7 and 99.2% for predicting pancreatic and extrapancreatic complications with areas under the curve (AUC) of 0.96 and 0.96, respectively. Balthazar grade of > C yielded a sensitivity of 98.4% for predicting pancreatic and extrapancreatic complications with an AUC of 0.95. The modified version of CTSI had the most significant association with pancreatic and extrapancreatic complications (HR: 3.22; p = 0.002, HR: 2.99, p = 0.003, respectively). Pancreatic necrosis was the only parameter significantly associated with mortality (HR: 5.83, p = 0.045).

Conclusion

Early CT scan has an important role in prediction of complications and the management of acute pancreatitis.

     

Pancreatic neuroendocrine tumour (PNET): Staging accuracy of MDCT and its diagnostic performance for the differentiation of PNET with uncommon CT findings from pancreatic adenocarcinoma

Purpose

To investigate staging accuracy of multidetector CT (MDCT) for pancreatic neuroendocrine tumour (PNET) and diagnostic performance for differentiation of PNET from pancreatic adenocarcinoma.

Material and methods

We included 109 patients with surgically proven PNET (NETG1?=?66, NETG2?=?31, NEC?=?12) who underwent MDCT. Two reviewers assessed stage and presence of predefined CT findings. We analysed the relationship between CT findings and tumour grade. Using PNETs with uncommon findings, we also estimated the possibility of PNET or adenocarcinoma.

Results

Accuracy for T stage was 85–88 % and N-metastasis was 83–89 %. Common findings included well circumscribed, homogeneously enhanced, hypervascular mass, common in lower grade tumours (p?<?0.05). Uncommon findings included ill-defined, heterogeneously enhanced, hypovascular mass and duct dilation, common in higher grade tumours (p?<?0.05). Using 31 PNETs with uncommon findings, diagnostic performance for differentiation from adenocarcinoma was 0.760–0.806. Duct dilatation was an independent predictor for adenocarcinoma (Exp(B)?=?4.569). PNETs with uncommon findings were associated with significantly worse survival versus PNET with common findings (62.7 vs. 95.7 months, p?<?0.001).

Conclusion

MDCT is useful for preoperative evaluation of PNET; it not only accurately depicts the tumour stage but also prediction of tumour grade, because uncommon findings were more common in higher grade tumours.

Key Points

? CT accurately depicts the T stage and node metastasis of PNET. ? Uncommon findings were more common in higher grade tumours. ? CT information may be beneficial for optimal therapeutic planning.

     

Diffusion-weighted MR imaging of the pancreas: optimizing b-value for visualization of pancreatic adenocarcinoma

Objectives

To determine the optimal b-value of 3.0-T diffusion-weighted imaging (DWI) for visualizing pancreatic adenocarcinomas

Methods

Fifty-five patients with histologically confirmed pancreatic adenocarcinoma underwent DWI with different b-values (b?=?500, 1000, 1500, and 2000 s/mm²) at 3.0 T. For each b-value, we retrospectively evaluated DWI findings of pancreatic adenocarcinomas (clear hyperintensity relative to the surrounding pancreas, hyperintensity with an unclear distal border, and isointensity) and image quality, and measured tumour-to-pancreas signal intensity (SI) ratios. DWI findings, image quality, and tumour-to-pancreas SI ratios were compared between the four b-values.

Results

There was a significantly higher incidence of tumours showing clear hyperintensity on DWI with b-value of 1500 s/mm² than on that with b-value of 1000 s/mm² (P?<?0.001), and on DWI with b-value of 1000 s/mm² than on that with b-value of 500 s/mm² (P?<?0.001). The tumour-to-distal pancreas SI ratio was higher with b-value of 1500 s/mm² than with b-value of 1000 s/mm² (P?<?0.001), and with b-value of 1000 s/mm² than with b-value of 500 s/mm² (P?<?0.001). A lower image quality was obtained at increasing b-values (P?<?0.001); the lowest scores were observed with b-value of 2000 s/mm².

Conclusions

The use of b?=?1500 s/mm² for 3.0-T DWI can improve the delineation of pancreatic adenocarcinomas.

Key Points

? Diffusion-weighted imaging (DWI) has been used for diagnosing pancreatic adenocarcinoma ? The techniques for DWI, including the choice of b-values, vary considerably ? DWI often fails to delineate pancreatic adenocarcinomas because of hyperintense pancreas ? DWI with a higher b-value can improve the tumour delineation ? The lowest image quality was obtained on DWI with b-value?=?2000 s/mm ²

     

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.

     

Role of radiotherapy in the chemotherapy-containing multidisciplinary management of patients with resected pancreatic adenocarcinoma

Background

To analyze prognostic factors associated with long-term outcomes in patients with resected pancreatic cancer treated with chemotherapy (CT) and surgery with or without external beam radiotherapy (EBRT).

Patients and methods

From January 1995 to December 2012, 95 patients with adenocarcinoma of the pancreas and locoregional disease [clinical stage IB-IIA (n?=?45; 47?%), IIB-IIIC (n?=?50; 53?%)] were treated with curative resection [R0 (n?=?52; 55?%), R1 (n?=?43, 45?%)] and CT with (n?=?60; 63?%) or without (n?=?35; 37?%) EBRT (45–50.4 Gy). Additionally, 29 patients (48?%) also received a pre-anastomosis IOERT boost (applicator diameter size, 7–10 cm; dose, 10–15 Gy; beam energy, 9–18 MeV).

Results

With a median follow-up of 17.2 months (range, 1–182), 2-year overall survival (OS), disease-free survival (DFS), and locoregional control were 28, 20, and 53?%, respectively. Univariate analyses showed that IIB-IIIC stage (HR, 2.23; p?=?0.04), R1 margin resection status (HR, 2.09; p?=?0.04), no vascular resection (HR, 0.42; p?=?0.02), and not receiving external beam radiotherapy (HR, 2.70; p?=?0.004) were associated with locoregional recurrence. In the multivariate analysis, only R1 margin resection status (HR, 2.63; p?=?0.009) and not receiving EBRT (HR, 2.91; p?=?0.002) retained significance with regard to locoregional recurrence. We observed no difference in toxicity between patients treated with or without EBRT (p?=?0.44). Overall treatment mortality was 3?%. No long-term treatment–related death occurred.

Conclusions

Although adjuvant CT is still the standard of care for resected pancreatic tumors, OS remains modest owing to the high risk of distant metastases. Locoregional treatment needs to be tested in the context of more efficient systemic therapy.

     

Using intravoxel incoherent motion MR imaging to study the renal pathophysiological process of contrast-induced acute kidney injury in rats: Comparison with conventional DWI and arterial spin labelling

Objectives

To investigate the potential of intravoxel incoherent motion (IVIM) to assess the renal pathophysiological process in contrast-induced acute kidney injury (CIAKI).

Methods

Twenty-seven rats were induced with CIAKI model, six rats were imaged longitudinally at 24 h prior to and 30 min, 12, 24, 48, 72 and 96 h after administration; three rats were randomly chosen from the rest for serum creatinine and histological studies. D, f, D* and ADC were calculated from IVIM, and renal blood flow (RBF) was obtained from arterial spin labelling (ASL).

Results

A progressive reduction in D and ADC was observed in cortex (CO) by 3.07 and 8.62 % at 30 min, and by 25.77 and 28.16 % at 48 h, respectively. A similar change in outer medulla (OM) and inner medulla (IM) was observed at a later time point (12–72 h). D values were strongly correlated with ADC (r?=?0.885). As perfusion measurement, a significant decrease was shown for f in 12–48 h and an increase in 72–96 h. A slightly different trend was found for D*, which was decreased by 26.02, 21.78 and 10.19 % in CO, OM and IM, respectively, at 30 min. f and D* were strongly correlated with RBF in the cortex (r?=?0.768, r?=?0.67), but not in the medulla.

Conclusions

IVIM is an effective imaging tool for monitoring progress in renal pathophysiology undergoing CIAKI.

Key Points

? IVIM analysis permits separate quantification of diffusion and perfusion. ? IVIM can provide useful biomarkers ifor changes in renal pathophysiology. ? IVIM can be useful for monitoring progress in renal pathophysiology undergoing CIAKI.

     

Neoadjuvant chemoradiation therapy with gemcitabine/cisplatin and surgery versus immediate surgery in resectable pancreatic cancer

Background

In nonrandomized trials, neoadjuvant treatment was reported to prolong survival in patients with pancreatic cancer. As neoadjuvant chemoradiation is established for the treatment of rectal cancer we examined the value of neoadjuvant chemoradiotherapy in pancreatic cancer in a randomized phase II trial. Radiological staging defining resectability was basic information prior to randomization in contrast to adjuvant therapy trials resting on pathological staging.

Patients and methods

Patients with resectable adenocarcinoma of the pancreatic head were randomized to primary surgery (Arm A) or neoadjuvant chemoradiotherapy followed by surgery (Arm B), which was followed by adjuvant chemotherapy in both arms. A total of 254 patients were required to detect a 4.33-month improvement in median overall survival (mOS).

Results

The trial was stopped after 73 patients; 66 patients were eligible for analysis. Twenty nine of 33 allocated patients received chemoradiotherapy. Radiotherapy was completed in all patients. Chemotherapy was changed in 3 patients due to toxicity. Tumor resection was performed in 23 vs. 19 patients (A vs. B). The R0 resection rate was 48?% (A) and 52?% (B, P?=?0.81) and (y)pN0 was 30?% (A) vs. 39?% (B, P?=?0.44), respectively. Postoperative complications were comparable in both groups. mOS was 14.4 vs. 17.4 months (A vs. B; intention-to-treat analysis; P?=?0.96). After tumor resection, mOS was 18.9 vs. 25.0 months (A vs. B; P?=?0.79).

Conclusion

This worldwide first randomized trial for neoadjuvant chemoradiotherapy in pancreatic cancer showed that neoadjuvant chemoradiation is safe with respect to toxicity, perioperative morbidity, and mortality. Nevertheless, the trial was terminated early due to slow recruiting and the results were not significant. ISRCTN78805636; NCT00335543.

     

Feasibility of test-bolus DCE-MRI using CAIPIRINHA-VIBE for the evaluation of pancreatic malignancies

Objectives

To evaluate the feasibility of test-bolus dynamic contrast-enhanced (DCE) MRI with CAIPIRINHA-VIBE for pancreatic malignancies.

Methods

Thirty-two patients underwent DCE-MRI with CAIPIRINHA-VIBE after injection of 2 mL gadolinium. From the resulting time–intensity curve (TIC), we estimated the arterial (AP) and portal venous phase (PVP) scan timing for subsequent multiphasic MRI. DCE-MRI perfusion maps were generated, and perfusion parameters were calculated. The image quality was rated on a 5-point scale (1: poor, 5: excellent). Goodness-of-fit of the TIC was evaluated by Pearson’s χ² test.

Results

Test-bolus DCE-MRIs with high temporal (3 s) and spatial resolution (1?×?1?×?4 mm³) were acquired with good-quality perfusion maps of Ktrans and iAUC (mean score 4.313?±?0.535 and 4.125?±?0.554, respectively). The mean χ² values for fitted TICs were 0.115?±?0.082 for the pancreatic parenchyma and 0.784?±?0.074 for pancreatic malignancies, indicating an acceptable goodness-of-fit. Test-bolus DCE-MRI was highly accurate in estimating the proper timing of AP (90.6 %) and PVP (100 %) of subsequent multiphasic MRI. Between pancreatic adenocarcinomas and neuroendocrine tumours, there were significant differences in the Ktrans (0.073?±?0.058 vs. 0.308?±?0.062, respectively; p?=?0.007) and iAUC (1.501?±?0.828 vs. 3.378?±?0.378, respectively; p?=?0.045).

Conclusions

Test-bolus DCE-MRI using CAIPIRINHA-VIBE is feasible for incorporating perfusion analysis of pancreatic tumours into routine multiphasic MRI.

Key Points

? Test-bolus DCE-MRI using CAIPIRINHA-VIBE is feasible for perfusion analysis of pancreatic tumours. ? CAIPIRINHA-VIBE enables DCE-MRI with high temporal and spatial resolution. ? Test-bolus DCE-MRI is highly accurate in estimating the proper timing of multiphasic MRI.

     

Enhancing pancreatic mass with normal serum CA19-9: key MDCT features to characterize pancreatic neuroendocrine tumours from its mimics

Objectives

To determine key MDCT features for characterizing pancreatic neuroendocrine tumours (PNET) from their mimics, which manifest as enhancing pancreatic mass with normal serum CA19-9 level.

Methods

This retrospective study had institutional review board approval and informed consent was waived. Preoperative multiphase MDCT of 74 patients with enhancing pancreatic masses and normal serum CA19-9 levels were included. Surgical pathologies were PNET (n = 42), microcystic serous cystadenomas (m-SCN, n = 12) and solid pseudopapillary epithelial neoplasms (SPEN, n = 20). Two radiologists independently evaluated CT images with a checklist of findings. Frequencies of findings with each disease entity were compared. Diagnostic accuracy was assessed using the key MDCT features alone and in combination. Inter-observer agreement was evaluated.

Results

The most common findings for PNET were mosaic morphological pattern (33/42, 78.6%) and enhancement peak in pancreatic arterial phase (PAP, 32/42, 76.2%), for m-SCN were honeycomb pattern (9/12, 75.0%) and enhancement peak in PAP (10/12, 83.3%) and for SPEN were melting icecream pattern (16/20, 80.0%) and hypo-enhancement in all phases (18/20, 90.0). Using a combination of morphological patterns and enhancement features, PNET was identified with 88% sensitivity and 81% specificity, m-SCN was identified with 83% sensitivity and 94% specificity, and SPEN was identified with 90% sensitivity and 91% specificity. Inter-observer agreement concerning CT findings was good to excellent (κ = 0.68 to 0.81, all p < 0.01).

Conclusions

Morphological features and enhancement patterns on MDCT are key features for characterizing enhancing pancreatic mass with normal serum CA19-9. PNET could be differentiated from its mimics with high accuracy.

     

Prognostic value of CT findings to predict survival outcomes in patients with pancreatic neuroendocrine neoplasms: a single institutional study of 161 patients

Objectives

To evaluate the prognostic value of CT to predict recurrence-free and overall survival in patients with pancreatic neuroendocrine neoplasms (PanNENs).

Methods

Between January 2004 and December 2012, 161 consecutive patients who underwent preoperative triphasic CT and surgical resection with curative intent for PanNENs were identified. The tumour consistency, margin, presence of calcification, pancreatic duct dilatation, bile duct dilatation, vascular invasion, and hepatic metastases were evaluated. The tumour size, arterial enhancement ratio, and portal enhancement ratio were measured. The Cox proportional hazard model was used to determine the association between CT features and recurrence-free survival and overall survival.

Results

By multivariate analysis, tumour size (>3 cm) (hazard ratio, 3.314; p?=?0.006), portal enhancement ratio (≤1.1) (hazard ratio, 2.718; p?=?0.006), and hepatic metastases (hazard ratio, 4.374; p?=?0.003) were independent significant variables for worse recurrence-free survival. Portal enhancement ratio (≤1.1) (hazard ratio, 5.951; p?=?0.001) and hepatic metastases (hazard ratio, 4.122; p?=?0.021) were independent significant variables for worse overall survival.

Conclusions

Portal enhancement ratio (≤1.1) and hepatic metastases assessed on CT were common independent prognostic factors for worse recurrence-free survival and overall survival in patients with PanNENs.

Key points

? CT is useful to predict survival outcomes in patients with PanNENs.? Survival outcomes are associated with portal enhancement ratio and hepatic metastases.? Portal enhancement ratio is prognostic CT biomarker in patients with PanNENs.

     

IVIM DW-MRI of autoimmune pancreatitis: therapy monitoring and differentiation from pancreatic cancer

Objectives

To evaluate IVIM DW-MRI for changes in IVIM-derived parameters during steroid treatment of autoimmune pancreatitis (AIP) and for the differentiation from pancreatic cancer (PC).

Methods

Fifteen AIP-patients, 11 healthy patients and 20 PC-patients were examined with DWI-MRI using eight b-values (50, 100, 150, 200, 300, 400, 600, 800). 12 AIP-patients underwent follow-up examinations during treatment. IVIM-parameters and ADC₈₀₀-values were tested for significant differences and an ROC analysis was performed.

Results

The perfusion fraction f was significantly lower in patients with AIP at the time of diagnosis (10.5?±?4.3 %) than in patients without AIP (20.7?±?4.3 %). In AIP follow-up, f increased significantly to 17.1?±?7.0 % in the first and 21.0?±?4.1 % in the second follow up. In PC, the f-values were lower (8.2?±?4.0 %, n.s.) compared to initial AIP and were significantly lower compared to first and second follow-up examination. In the ROC-analysis AUC-values for f were 0.63, 0.88 and 0.98 for differentiation of PC from initial, first and second follow up AIP-examination.

Conclusions

The found differences in f between AIP, AIP during steroid treatment and pancreatic cancer suggest that IVIM-diffusion MRI could serve as imaging biomarker during treatment in AIP-patients and as a helpful tool for differentiation between PC and AIP.

Key Points

? MRI is used for follow-up examinations during therapy in AIP-patients ? IVIM-DWI-MRI offers parameters which reflect perfusion and true diffusion ? IVIM-parameters are helpful for differentiation between AIP and pancreatic cancer ? IVIM-parameters could serve as an imaging biomarker during steroid treatment

     

Secretin-stimulated ultrasound estimation of pancreatic secretion in cystic fibrosis validated by magnetic resonance imaging

Objectives

Secretin-stimulated magnetic resonance imaging (s-MRI) is the best validated radiological modality assessing pancreatic secretion. The purpose of this study was to compare volume output measures from secretin-stimulated transabdominal ultrasonography (s-US) to s-MRI for the diagnosis of exocrine pancreatic failure in cystic fibrosis (CF).

Methods

We performed transabdominal ultrasonography and MRI before and at timed intervals during 15 minutes after secretin stimulation in 21 CF patients and 13 healthy controls. To clearly identify the subjects with reduced exocrine pancreatic function, we classified CF patients as pancreas-sufficient or -insufficient by secretin-stimulated endoscopic short test and faecal elastase.

Results

Pancreas-insufficient CF patients had reduced pancreatic secretions compared to pancreas-sufficient subjects based on both imaging modalities (p < 0.001). Volume output estimates assessed by s-US correlated to that of s-MRI (r = 0.56–0.62; p < 0.001). Both s-US (AUC: 0.88) and s-MRI (AUC: 0.99) demonstrated good diagnostic accuracy for exocrine pancreatic failure.

Conclusions

Pancreatic volume-output estimated by s-US corresponds well to exocrine pancreatic function in CF patients and yields comparable results to that of s-MRI. s-US provides a simple and feasible tool in the assessment of pancreatic secretion.

Key points

? Cystic fibrosis patients with affected pancreas have reduced pancreatic secretions. ? Secretin-stimulated sonography is a simple and feasible method to assess pancreatic output. ? Secretin-simulated MRI is a more precise method to assess pancreatic secretions. ? The sonographic and MRI methods yielded comparable pancreatic secretory output estimates.

     

Magnetic resonance cholangiopancreatography with GRASE sequence at 3.0T: does it improve image quality and acquisition time as compared with 3D TSE?

Objectives

The current study evaluated the clinical usefulness of the gradient and spin-echo (GRASE) sequence with single breath-hold in 3.0 T magnetic resonance cholangiopancreatography (MRCP). We compared the acquisition time and image quality between GRASE and breath navigator-triggered 3D turbo spin echo (3D TSE).

Methods

We examined 54 consecutive patients who underwent MRCP with GRASE and 3D TSE. We compared the image acquisition time and contrast-to-noise ratio (CNR) between the common bile duct (CBD) and liver. Overall image quality, blurring, motion artifacts and CBD visibility were scored on a 4-point scale by two radiologists. Paired t-tests were used to compare the variables.

Results

The mean image acquisition time was 95 % shorter with the GRASE than with 3D TSE (GRASE: 20 s; 3D TSE: 6 min 27 s). The CNR of GRASE was significantly higher than that of 3D TSE (GRASE: 25.4 ± 13.9 vs. 3D TSE: 18.2 ± 9.6, p < 0.01). All qualitative scores for GRASE were significantly better than those for 3D TSE.

Conclusions

3.0 T MRCP with GRASE sequence with single breath-hold significantly improved the CNR of CBD with a 95 % shorter acquisition time compared with conventional 3D MRCP with 3D TSE.

Key Points

? MRCP acquisition time was 95% shorter with GRASE than with 3D TSE.? Overall image quality of GRASE was significantly better than 3D TSE.? Pancreaticobiliary tree visibility with GRASE was better than that with 3D TSE.

     

Evaluation of the degree of pancreatic fatty infiltration by area-based assessment of CT images: comparison with histopathology-based and CT attenuation index-based assessments

Purpose

The purpose of this study was to evaluate the degree of fatty infiltration (FI) of the pancreas using area-based assessment on computed tomography (CT) (CT area-based assessment) in its correlation and agreement/concordance with histopathology-based assessment. Furthermore, we examined whether CT area-based assessment was better than CT attenuation index-based assessment.

Materials and methods

We retrospectively evaluated the degree of FI of the pancreas in 37 pancreatic cancer patients who had undergone preoperative CT and pancreaticoduodenectomy. The degree of FI of the pancreas was examined by histopathology-based assessment using surgical resection samples, and CT area-based and CT attenuation index-based assessments.

Results

Mean values of pancreatic FI measured by area-based assessment on unenhanced CT and by histopathology-based assessments were 14.4 ± 23.2 % (range 0–77.7 %) and 16.2 ± 17.4 % (range 0.2–60.2 %), respectively. Area-based assessment on unenhanced CT showed higher correlation and concordance with histopathology-based assessment, demonstrating a Spearman correlation coefficient of 0.78 (P < 0.0001) and a Kendall’s tau-b coefficient of 0.69 (P < 0.0001). For CT attenuation index-based assessment, the corresponding values were ?0.66 (P < 0.0001) and ?0.39 (P = 0.008), respectively.

Conclusions

To order/categorize subjects according to the degree of FI of the pancreas, CT area-based assessment is suggested to be better than CT attenuation index-based assessment.

     

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.

     

Simultaneous whole-body and breast 18F-FDG PET/MRI examinations in patients with breast cancer: a comparison of apparent diffusion coefficients and maximum standardized uptake values

Purpose

To compare standardized uptake value (SUV) and apparent diffusion coefficient (ADC) values acquired using a PET/MRI scanner in breast cancer patients.

Materials and methods

Whole-body PET/MRI and breast PET/MRI were performed in 108 consecutive patients. Ninety-four patients who had a total of 100 breast cancers were analyzed. SUVmax and ADCmean acquired using breast PET/MRI were compared with pathologic prognostic factors.

Results

All the lesions were visually detectable using PET and diffusion-weighted imaging (DWI) on breast PET/MRI; however, lesions were visually undetectable on whole-body DWI in 13 patients (13%) or on whole-body PET in 7 patients (7%). An analysis of ADCmean and SUVmax demonstrated a statistically significant correlation between whole-body imaging and breast imaging (rho = 0.613, p < 0.001 and rho = 0.928, p < 0.001, respectively). In a univariate analysis, SUVmax was significantly correlated with HER2 status (p < 0.001), Ki-67 (p = 0.014), tumor size (p = 0.0177), and nuclear grade (p = 0.0448). In multiple regression analysis, only tumor size (p = 0.00701) was shown to independently influence SUVmax.

Conclusion

Prone breast imaging was more sensitive than whole-body PET/MRI for detection of breast cancers. Both SUVmax and ADCmean showed limited correlation with pathologic prognostic factors.

     

Retrospective review of thoracic neural damage during lung ablation – what the interventional radiologist needs to know about neural thoracic anatomy

Background and Purpose

Radiofrequency ablation (RFA) is associated with low neural morbidity compared with surgery, which commonly causes debilitating long-term pain. The purpose was to review the thoracic neural anatomy relevant to percutaneous RFA and to retrospectively review symptomatic nerve injury after lung RFA at our institution.

Materials and Methods

We retrospectively examined all symptomatic nerve injuries occurring after computed tomography (CT)-guided RFA treatment of lung tumors for 462 patients/509 procedures/708 lesions treated at our large tertiary referral centre during 10 years.

Results

Eight patients experienced neurological complications after heating during the RFA procedure. These complications occurred in the phrenic (n = 1), brachial (n = 3), left recurrent (n = 1), and intercostal nerves (n = 2) and the stellate ganglion (n = 1). Three were grade 2, four grade 3 and one grade 4 injuries (CTCAE v3).

Conclusion

Although rare, neurological complications can occur after RFA, and they can occasionally be severe. To prevent these complications, it is important for the interventional radiologist to be aware of the anatomy of nervous structures and to attempt to identify nerves on CT scans during the RFA procedure. Creating a pneumothorax can be useful to avoid nerve damage and related clinical complications.

     

Multiparametric PET/MR imaging biomarkers are associated with overall survival in patients with pancreatic cancer

Purpose

To correlate the overall survival (OS) with the imaging biomarkers of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), diffusion-weighted imaging (DWI), magnetic resonance spectroscopy, and glucose metabolic activity derived from integrated fluorine 18 fluorodeoxyglucose positron emission tomography (¹⁸F–FDG PET)/MRI in patients with pancreatic cancer.

Methods

This prospective study was approved by the institutional review board and informed consent was obtained from all participants. Sixty-three consecutive patients (mean age, 62.7?±?12 y; men/women, 40/23) with pancreatic cancer underwent PET/MRI before treatment. The imaging biomarkers were comprised of DCE-MRI parameters (peak, IAUC ₆₀ , K ^trans , k _ep , v _e ), the minimum apparent diffusion coefficient (ADC_min), choline level, standardized uptake values, metabolic tumor volume, and total lesion glycolysis (TLG) of the tumors. The relationships between these imaging biomarkers with OS were evaluated with the Kaplan-Meier and Cox proportional hazard models.

Results

Seventeen (27%) patients received curative surgery, with the median follow-up duration being 638 days. Univariate analysis showed that patients at a low TNM stage (≦3, P?=?0.041), high peak (P?=?0.006), high ADC_min (P?=?0.002) and low TLG (P?=?0.01) had better OS. Moreover, high TLG/peak ratio was associated with poor OS (P?=?0.016). Multivariate analysis indicated that ADC_min (P?=?0.011) and TLG/peak ratio (P?=?0.006) were independent predictors of OS after adjustment for age, gender, tumor size, and TNM stage. The TLG/peak ratio was an independent predictor of OS in a subgroup of patients who did not receive curative surgery (P?=?0.013).

Conclusion

The flow-metabolism mismatch reflected by the TLG/peak ratio may better predict OS than other imaging biomarkers from PET/MRI in pancreatic cancer patients.

     

Nonmetastatic pancreatic cancer

Purpose

The role of radiotherapy (RT) for nonmetastatic pancreatic cancer is still a matter of debate since randomized control trials have shown inconsistent results. The current retrospective single-institution study includes both resected and unresected patients with nonmetastasized pancreatic cancer. The aim is to analyze overall survival (OS) after irradiation combined with induction chemotherapy.

Patients and methods

Of the 73 patients with nonmetastatic pancreatic cancer eligible for the present analysis, 42 (58%) patients had adjuvant chemoradiotherapy (CRT), while 31 (42%) received CRT as primary treatment. In all, 65 (89%) had chemotherapy at any time before, during, or after RT, and 39 (53%) received concomitant CRT. The median total dose was 50?Gy (range 12–77?Gy), while 61 (84%) patients received >40?Gy.

Results

With a median follow-up of 22 months (range 1.2–179.8 months), 14 (19%) are still alive and 59 (81%) of the patients have died, whereby 51 (70%) were cancer-related deaths. Median OS and the 2?year survival rate were 22.9 months (1.2–179.8 months) and 44%, respectively. In addition, 61 (84%) patients treated with >40?Gy had a survival advantage (median OS 23.7 vs. 17.3 months, p?=?0.026), as had patients with 4 months minimum of systemic treatment (median OS 27.5 vs. 14.3 months, p?=?0.0004).

Conclusion

CRT with total doses >40?Gy after induction chemotherapy leads to improved OS in patients with nonmetastatic pancreatic cancer.