How Impedance Measurements and Imaging Can Be Used to Characterize the Conductivity of Tissues During the Workflow of an Electroporation-Based Therapy.

In this article we investigate the possibility of using needles, which the interventional radiologist inserts near a deep-seated tumor during an electroporation-based therapy, to characterize the electrical conductivity of patient's tissues. Specifically, we propose to exploit voltage/current measurements and imaging that are performed prior to the application of electroporation pulses. The approach is partly based on the concepts of electrical impedance tomography; however, imaging is used to build a specific geometric model and compensate for the lack of information resulting from the small number of electrodes available. 3D canonical and clinical examples, where a few electrodes surround a tumor, demonstrate the feasibility of this method: solving the inverse problem to estimate tissues conductivity converges in a few iterations. For a given error on the measurement, it is also possible to calculate the error on the estimated conductivities. The uncertainty error with clinical data is at best 5% for one of the tissues identified, due to the limitations of the clinical device used. Various improvements to clinical devices are discussed to make the conductivity estimation more accurate but also to extract more information.

Avascular osteonecrosis of the hip: The vision of the radiologist (radiology, MRI, CT and scintigraphy).

Hip osteonecrosis is a localization at the hip of aseptic osteonecrosis, a disease characterized by bone infarction. Face to a painful hip, the first examination to carry out should be a standard radiograph examination. At an early stage, the radiographs remain strictly normal MRI remains the reference examination with a sensitivity of 71-100% and specificity of 94-100%. On T2 weighting-imaging, a hyperintense line between the normal and ischemic marrow is sometimes visible; this sign is pathognomonic of bone necrosis and is known as the "double line sign". This article reviews imaging features of standard radiographs, computed tomography and MRI and addresses the role of imaging in this pathology.

Glioma-grade diagnosis using in-phase and out-of-phase T1-weighted magnetic resonance imaging: A prospective study.

PURPOSE: The purpose of this prospective study was to determine whether chemical shift gradient-echo magnetic resonance imaging (MRI) could predict glioma grade. MATERIALS AND METHODS: A total of 69 patients with 69 gliomas were prospectively included. There were 41 men and 28 women with a mean age of 50±(SD) years (range: 16-82years). All patients had MRI of the brain including chemical shift gradient-echo sequence, further referred to as in- and out-of phase sequence (IP/OP). Intravoxel fat content was estimated by signal loss ratio (SLR=[IP-OP]/2IP), between in- and out-of-phase images, using a region of interest placed on the viable portion of the gliomas. Association between SLR and glioma grade was searched for using Wilcoxon and Mann-Whitney U tests and diagnostic capabilities using area under the receiver operating characteristic (AUROC) curves. RESULTS: A significant association was found between SLR value and glioma grade (P<0.0001). SLR>9‰ allowed complete discrimination between grade III and grade II glioma with 100% specificity (95% CI: 85-100%), 100% sensitivity (95% CI: 78-100%) and 100% accuracy (95% CI: 90-100%) (AUROC=1). A SLR>20‰ allowed discriminating between grade IV and grade III glioma with 75% specificity (95% CI: 57-89%), 73% sensitivity (95% CI: 45-92%) and 72% accuracy (95% CI: 57-84%) (AUC=0.825, 95% CI: 0.702-0.948). The AUROC for the diagnosis of high-grade glioma (grade III and IV vs. grade II) was 1. CONCLUSION: Chemical shift gradient echo MRI provides accurate grading of gliomas. This simple method should be used as a biomarker to predict glioma grade.

Intra peritoneal abdominal fat area measured from computed tomography is an independent factor of severe acute pancreatitis.

PURPOSE: The purpose of this study was to search for a possible relationship between acute pancreatitis (AP) severity and visceral fat (VF) surface on contrast-enhanced computed tomography (CECT). MATERIAL AND METHOD: A total of 112 patients with AP who underwent CECT within 2 to 3 days after the beginning of AP were included. There were 68 mean and 44 women, with a mean age of 56.3±21.6 (SD) years (range: 19-98 years). AP was regarded as mild for patients with an hospital stay up to 5 days and severe for those with an hospital stay greater than 5 days. VF surface was measured on CECT at the level of L4-L5 and of the umbilicus. Association between AP severity and VF surface, computed tomography severity index (CTSI), modified CTSI (mCTSI) and other variables were searched for using uni- and multivariate analysis. RESULTS: At univariate analysis, the VF surface at the level of L4 was greater in patients with severe AP (129.3±68.6 [SD] cm2; range: 21.8-355.8 cm2) than in patients with mild AP (100.1±68.4 [SD] cm2; range:13.2-333 cm2) (P=0.006). Similarly, the VF surface at the umbilicus was greater in patients with severe AP (161.1±76.1 [SD] cm2; range: 31.3-376.7cm2) than in those with mild AP (128.4±74.3cm2; range: 12.8-323.1cm2) (P=0.024). CTSI and mCTSI were also associated to AP severity. At multivariate analysis, only VF surface either measured at the umbilical or at the L4-L5 level was associated with AP severity (P=0.017 and 0.006, respectively). CONCLUSION: VF surface at the level of L4-L5 on CECT is an independent factor of AP severity. VF surface at the level of L4-L5 on CECT is an independent factor of AP severity. These results are in line with recent data on the role of abdominal fat in the genesis of inflammatory response, which is associated with severe forms of AP.

Chart for renal tumor microwave ablation from human study.

PURPOSE: To define microwave ablation (MWA) charts according to time and power in human renal tumors and to compare them to the charts given by the HS AMICA manufacturer. MATERIALS AND METHODS: A total of 54 patients with 54 renal cancers who underwent MWA were included. There were 36 men and 18 women with a mean age of 72.5±10[SD] years (range: 40-91years). The system used for MWA was HS AMICA with the Amica-probe V4 applicator. The following variables (antero-posterior diameter, transverse diameter, cranio-caudal diameter and volume were measured on computed tomography examinations performed one month after MWA. The dimensions of the ablation zone were correlated with power (40 or 60W) and exposure time (5, 10 and 15min) used for MWA. Actual ablation dimensions were compared to the manufacturer's data. RESULTS: The variation of diameters, with a longer ablation time, was linear at 40W with a volume increase of 30% for each additional 5minutes. At 60W, a more pronounced variation (volume increase of 112%) was observed. Compared to the manufacturer's chart, significantly larger ablation zones were obtained (P<0.05), the differences being mainly marked for the antero-posterior diameter (≥1cm). CONCLUSION: MWA using AMICA generator produces reproducible ablation area for given time and power in renal tumor ablation. The charts presented here should be used instead of the manufacturer's chart, which is based on porcine liver and is significantly different.

Transarterial chemoembolization (TACE) in the management of hepatocellular carcinoma: Results of a French national survey on current practices.

PURPOSE: To report current practices of transarterial chemoembolization (TACE) by interventional radiologists (IR) for hepatocellular carcinoma (HCC) through a French national survey. MATERIALS AND METHODS: An electronic survey was sent by e-mail to 232 IRs performing TACE in 32 private or public centers. The survey included 66 items including indications for TACE, technical aspects of TACE, other locally available treatments for HCC, follow-up imaging and general aspects of interventional radiology practices. RESULTS: A total of 64 IRs (64/232; 27%) answered the survey. Each IR performed a mean of 49±45 (SD) TACE procedures per year. Marked variations in indications for TACE in HCC were observed. Six percent of IRs (4/64) treated only patients with Barcelona Clinic Liver Cancer (BCLC) stage B HCC. Antibioprophylaxis was not used by 43/64 of IRs (67%). The number of HCC nodules was considered to select conventional TACE versus drug-eluting beadsTACE (DEB-TACE) by 17/49 IRs (35%) followed by patient performance status and Child-Pugh score by 6/49 IRs (12%). Seventy-three percent of IRs (45/62) treated nodules selectively in patients with unilobar disease with cTACE. Thirty-three percent of IRs (21/64) planned systematically a second TACE session. Doxorubicin was the most frequently used drug (52/64; 81%) and 15/64 IRs (23%) used gelatine sponge as the only embolic agent. For DEB-TACE, 100-300µm beads were used by 26/49 IRs (53%) and no additional embolization was performed by 19/48 IRs (39%). Monopolar radiofrequency technique was widely available (59/63; 94%) compared to selective internal radiation therapy (37/64; 58%). Magnetic resonance imaging was used for follow-up by 13/63 IRs (20%). CONCLUSION: Current practices of TACE for HCC varied widely among IRs suggesting a need for more standardized practices.

Left atrial volume assessed by ECG-gated computed tomography: Variations according to age, gender and time during the cardiac cycle.

PURPOSE: The purpose of this study was to retrospectively assess the accuracy of the maximal left atrial volume (LAVmax) measured at 75% of the cardiac cycle compared to the 40% measurements and to evaluate this volume according to age and gender. PATIENTS AND METHOD: A total of 150 patients with a mean age of 50±17 (SD) years (range: 21-79 years) were analyzed. There were 78 men and 72 women. LAVmax were measured from retrospective triphasic cardiac-gated multi-detector computed tomography (MDCT) data at the 40% (LAV40) and 75% (LAV75) of the RR cycle phases by a semi-automatic method. RESULTS: LAV40was 50.7±14mL/m2 and LAV75 was 42.5±13mL/m2. The difference was statistically significant. Considering the reference range of LAVmax reported in the literature, 33% of the patients had enlarged LA with LAV40 and only 17% with LAV75. These volumes were positively influenced by age but not by gender. The relationship between LAV75 and LAV40 was: LAV75=0.908 LAV40-3.486 (r2=0.92) or LAV40=1.1×LAV75+3.8 (r2=0.92). CONCLUSION: LAVmax measured at the 75% of the cardiac cycle phase significantly underestimates actual LAV leading to reconsider normal values. LAV40 can be computed from the measured value of LAV75 obtained on prospective ECG-gated MDCT.

[Estimating minimum period of time to perform prostate MRI after prostate biopsy: Clinical and histological bleeding risk factors; from a prospective study]. / Évaluation prospective du délai minimum de réalisation de l'IRM prostatique après une biopsie de prostate : facteurs prédictifs cliniques et anatomopathologiques de remaniements hémorragiques.

A minimum delay of 4 to 6 weeks between biopsy and multiparametric prostatic MRI (mpMRI) is admitted due to post-biopsy hemorrhage that can impact MRI reading without strong scientific evidence. The objective of the study was to evaluate the best period between prostate biopsy and 3Tesla mpMRI and searching for predictive factors of intraprostatic blood. METHOD: A prostate biopsy followed by a 4-week prostate MRI (MRIp M1) was performed. In case of hemorrhage, MRI was rescheduled at 8 and 12 weeks (M2/M3). We analyzed the persistant bleeding to identify risk factors: anticoagulant/antiaggregant, post-biopsy side effects, histological criteria. RESULTS: In this prospective, single-center study, we included 40 patients followed for suspected prostate cancer between December 2014 and March 2016. At the MRIpM1, blood was found for 97.5 % of the patients. The rates were 90.9 % and 88.9 % respectively at the M2 and M3 mpMRI. Compared to initial blood volume on MRIpM1, a significant decrease in blood volume was observed between M1 and M2 (55 %; P=0.0091). We showed a 75 % decrease between M1 and M3 (P=0.0003). Low urinary tract symptoms (LUTS) suggesting urinary infection at 4 weeks were significantly correlated with blood volume on MRIpM1 (P=0.0063). The blood volume was higher in case of unconformity between biopsy and mpMRI results for detection of significant tumors (11.3 vs. 2.3; P=0.0051). CONCLUSIONS: A minimum of 8-week biopsy and mpMRI period would limit post-biopsy hemorrhage, predicted by LUTS suggesting urinary infection. A delay of 12 weeks would be optimal without delaying the management of the patient. LEVEL OF EVIDENCE: 4.

Percutaneous microwave ablation of renal cancers under CT guidance: safety and efficacy with a 2-year follow-up.

AIM: To evaluate the safety and efficiency of percutaneous microwave ablation (MWA) of renal cell carcinomas (RCC) carried out under computed tomography (CT) guidance. MATERIALS AND METHODS: A retrospective study was performed on RCC that was either histologically proven or diagnosed at imaging (Bosniak IV cyst) and treated by MWA under general anaesthesia with CT guidance. Indications for percutaneous ablation were based on the American Urological Association recommendations. Twenty-four months post-procedure follow-up was performed. RESULTS: Sixty-two patients presenting one or more RCC (84 tumours ranging from 10-48 mm in diameter; mean diameter: 25.6 mm) were included. Technical success was achieved for 78 tumours (58 patients). For four patients, the treatment was stopped due to gas dissection failure. At 3 months, six residual tumours were observed (8%). At 6 months, two recurrences and one residual tumour (3.8%) were observed; all were retreated with complete success. At 12 months, local control of the disease was achieved in 94% of cases (100% in cases where treatment was performed). Two cases of distal metastasis were observed after 12 and 24 months. At 24 months, one patient presented with a contralateral tumour. The complication rate was 4.8% including one grade III complication and two grade II complications according to the Clavien-Dindo classification. At 2 years, the cumulative disease-free survival rate and overall survival were 95% and 97%, respectively. CONCLUSION: MWA ablation under CT guidance to treat RCC is safe and provides a high rate of effectiveness at 24 months.

Irreversible electroporation for locally advanced pancreatic cancer.

Pancreatic adenocarcinoma is one of the solid cancers associated with the poorest prognosis; the only curative treatment remains surgical resection but in most cases, this treatment is not possible because of distant metastasis or local extension. Irreversible electroporation is a new tumor ablation technique, which provides cellular apoptosis without any thermal coagulation effect. This technique helps preserve the ducts, vessels or nerves located in the treatment area. This article reviews the current knowledge regarding the use of electroporation for the treatment of pancreatic adenocarcinoma.

Preoperative detection of hepatic metastases from colorectal cancer: Prospective comparison of contrast-enhanced ultrasound and multidetector-row computed tomography (MDCT).

PURPOSE: The goal of this study was to prospectively compare the sensitivity of contrast-enhanced ultrasound (CEUS) with that of multiphase multidetector-row computed tomography (MDCT) in the preoperative detection of hepatic metastases. MATERIALS AND METHOD: Forty-eight patients, with a mean age of 62years old (range: 43-85years) were prospectively included. All patients underwent CEUS following intravenous administration of 2.4mL of an ultrasound contrast agent (Sonovue(®), Bracco, Milan, Italy) and multiphase MDCT. Intraoperative ultrasound examination (IOUS) was used as the standard of reference. RESULTS: A total of 158 liver metastases were identified by IOUS, 127 by preoperative MDCT (sensitivity; 80.4%) and 102 by CEUS (sensitivity, 64.5%). The 15.9% difference in sensitivity between CEUS and MDCT was statistically significant (P=0.002). There was a disagreement between IOUS and CEUS in 23 patients (47%) and in 13 patients (27%) between IOUS and MDCT. MDCT identified one or more additional metastases in 10 patients (20%) resulting in a change in the surgical strategy. CONCLUSION: Based on an unselected patient cohort and using multiphase MDCT, CEUS is significantly inferior to MDCT for the preoperative detection of hepatic metastases of colorectal cancer.

Postoperative abdominal bleeding.

Postoperative bleeding following abdominal surgery is relatively rare and mainly depends on the type of surgery. Although bleeding is usually controlled by simple local treatment of symptoms, specific treatment including surgery or interventional radiology is sometimes necessary. This article reviews the clinical features that must be recognized depending on the type of surgery and especially focuses on the role of the radiologist in the management of this complication.

Radioembolization with yttrium-90 microspheres work up: Practical approach and literature review.

Radioembolization (RE) is a selective internal radiotherapy technique in which yttrium-90 blended microspheres are infused through the hepatic arteries. It is based on the fact that primary and secondary hepatic tumors are vascularized mostly by arterial blood flow whereas healthy hepatocytes obtain their blood supply mostly from the portal network. This enables high radiation doses to be delivered, sparing the surrounding non-malignant liver parenchyma. Most of the complications are caused by unexpected particles passing into the gastrointestinal tract through branches originating from the main hepatic arterial supply. Knowledge of this hepatic arterial network and of its variations and the technical considerations this raises are required in preparation for treatment. This work describes the specific anatomical features and techniques for this anatomy through recent literature illustrated by cases from our own experience.

Comparison of whole-body diffusion MRI and conventional radiological assessment in the staging of myeloma.

PURPOSE: In multiple myeloma, skeletal radiographs are still regarded as the reference imaging examination because they help to establish the stage of the disease according to the Durie-Salmon Staging System. Whole-body MRI using T1 and STIR sequences increases the detection of myeloma lesions. MRI-measured diffusion has demonstrated high sensitivity in terms of detection in oncology. The main objective of this study is to compare conventional radiographic staging with an MRI whole-body diffusion technique (called DWIBS) in detecting bone lesion monoclonal plasma cell pathologies (multiple myeloma, plasma cell leukaemia, plasmacytoma and MGUS). MATERIALS AND METHODS: Twenty-seven patients were included (multiple myeloma: 24; plasma cell leukaemia, MGUS and plasmacytoma: 1 each). All of them had a whole-body MRI diffusion examination (using a DWIBS sequence). Diffusion MRI and conventional radiographs were compared according to the Durie-Salmon Staging System. In case of doubtful lesions, 12 months of monitoring was used as the reference method for the definitive diagnosis. RESULTS: The overall concordance rate between the two techniques was 63%. The DWIBS sequence detected a higher number of lesions leading to a higher Durie-Salmon stage in 37% of the patients: one stage I to II, seven stage I to III, and two stage II to III. In 18.5% of the patients, the MRI was positive while the radiographs were normal and these discrepancies were most often located in sites poorly explored by X-ray (spine, pelvis and ribs). In one patient (4%), the MRI provided a stage lower than that of the X-rays (stage II vs. III). In this case, the X-rays were positive at the humerus and femur, unlike the DWIBS sequence. Our per site analysis confirmed the clear superiority of the DWIBS sequence when compared with X-rays in the exploration of the cervical spine (56 vs. 0%, P<0.001), dorsal spine (81vs. 31%,P<0.0002), lumbar spine (70 vs. 35%, P<0.0124), pelvis (81 vs. 33%, P<0.0005) and ribs (74 vs. 36%, P<0.0009). CONCLUSION: The DWIBS MRI leads to an increase in the final Durie-Salmon stage. Although its place in the preoperative treatment of multiple myeloma still has to be assessed, this study suggests its potential interest.

[Chronic pericarditis: CT and MR imaging features]. / Pourquoi réaliser un scanner et une IRM dans une péricardite chronique?

A diagnosis of constrictive pericarditis is suggested by the presence of pericardial thickening (>=4 mm in thickness) and abnormal motion of the interventricular septum. Additional findings have been reported: tubular appearance of the right or left ventricles, dilatation of the vena cava, atrial dilatation or abnormal diastolic expansion of one or both ventricles. In patients with suspected chronic pericarditis, CT can more easily demonstrate the presence of pericardial calcifications compared to US and MRI, as well as detect the presence of mediastinal adenopathy and lung lesions, suggesting tuberculosis. Septal motion analysis should be performed during protodiastole and systole using a cine technique with both CT and MR.