Accuracy of iodine quantification in dual energy CT: A phantom study across 3 different CT systems.

INTRODUCTION: No study has rigorously compared the performances of iodine quantification on recent CT systems employing different emission-based technologies, depending on the manufacturers and models. METHODS: A specific bespoke phantom was used for this study, with 12 known concentrations of iodinated contrast agent: 0.4, 0.5, 1.0, 2.0, 3.0, 4.0, 5.0, 10.0, 15.0, 20.0, 30.0 and 50.0 mg/mL. Three different dual-energy scanners were tested: one system using dual-source acquisition (CT#1) and two systems using Fast kilovolt-peak switching technology ± artificial intelligence (AI) reconstruction methods (CT#2 and #3) from two different manufacturers. For each system, helical scans were performed following recommended clinical protocols. Four acquisitions were performed per iodine concentration (mg/mL), and measurements were made on iodine-maps using ROIs. Mean measured values were compared to the known concentrations, and the absolute quantification error (AQE) and the relative percentage error (RPE) were used to compare the performances of each CT. RESULTS: The accuracy of the obtained measurements varied depending on the studied model but not on the acquisition mode (dual-source vs kVp switch ± AI). The quantification was more precise at high concentrations. RPE values were below 10 % with CT#2 (kVp switch) and below 25 % with CT#1 (dual-source), but were significantly higher with CT#3 (kVp switch + AI), exceeding 50 % at low concentrations (<3 mg/mL). CONCLUSIONS: With the help of a phantom, we identified variability in the results accuracy depending on the CT model, with sometimes significant deviation. Considering the performances of the different DECT technologies in iodine mapping, dual-source (CT#1) and kVp switch (CT#2) technologies appear more accurate than kVp switch technology combined with deep-learning-based reconstruction (CT#3) especially at low concentrations (<3 mg/mL). IMPLICATIONS FOR PRACTICE: As the primary and daily user of medical imaging devices, the radiographer role is to be attentive to the performance of imaging systems, particularly when performing quantitative acquisitions like iodine-quantification. In CT quantitative imaging (iodine map), it's essential for radiographers to consider their CT systems as measuring tools, and to be aware of their accuracies and limits.

[Pulmonary re-expansion in metastatic pleural effusions after thoracentesis: A pilot study]. / Échogénicité des pleurésies : facteur prédictif d'amélioration de la dyspnée ? Étude pilote concernant les pleurésies métastatiques.

INTRODUCTION: Metastatic pleural effusion is a cause of dyspnea. The American thoracic society has strongly suggested that studies evaluating thoracic ultrasonography as potentially predictive of improvment of dyspnea are needed. METHODS: We conducted a prospective monocentric observational study to assess chest ultrasound predictors of response to thoracentesis. Fifteen patients with metastatic pleural effusion were included. RESULTS: The initial mean VAS score was5 ± 2,9 cm. The majority of patients had pleural effusions equal to or greater than 5 intercostal spaces (EIC) in height, while 7 patients had an abnormal curvature of the hemidiaphragm (flattened or inverted). PRIMARY ENDPOINT: The volume removed was greater in the group with anechoic pleurisy compared to the group with sonographic septation, notwithstanding complex pleural effusion (non-septated, relatively hyperechoic, with some spots in the effusion). The patients with complex pleural effusions had an higher score of dyspnea. SECONDARY ENDPOINTS: The 7 patients with abnormal diaphragmatic curvature presented significant dyspnea with a pain score of approximately 7 and profuse pleurisy occupying 8 intercostal spaces in height. The effusions of those who could not normalize their curvature had a complex aspect and the volume removed was lower. CONCLUSIONS: The ultrasound characteristics of pleural effusions seem to be predictors of improvment of dyspnea after thoracentesis. The septated and complex aspects are probably predictors of non improvment of dyspnea.

Artificial intelligence solution to classify pulmonary nodules on CT.

PURPOSE: The purpose of this study was to create an algorithm to detect and classify pulmonary nodules in two categories based on their volume greater than 100 mm3 or not, using machine learning and deep learning techniques. MATERIALS AND METHOD: The dataset used to train the model was provided by the organization team of the SFR (French Radiological Society) Data Challenge 2019. An asynchronous and parallel 3-stages pipeline was developed to process all the data (a data "pre-processing" stage; a "nodule detection" stage; a "classifier" stage). Lung segmentation was achieved using 3D U-NET algorithm; nodule detection was done using 3D Retina-UNET and classifier stage with a support vector machine algorithm on selected features. Performances were assessed using area under receiver operating characteristics curve (AUROC). RESULTS: The pipeline showed good performance for pathological nodule detection and patient diagnosis. With the preparation dataset, an AUROC of 0.9058 (95% confidence interval [CI]: 0.8746-0.9362) was obtained, 87% yielding accuracy (95% CI: 84.83%-91.03%) for the "nodule detection" stage, corresponding to 86% specificity (95% CI: 82%-92%) and 89% sensitivity (95% CI: 84.83%-91.03%). CONCLUSION: A fully functional pipeline using 3D U-NET, 3D Retina-UNET and classifier stage with a support vector machine algorithm was developed, resulting in high capabilities for pulmonary nodule classification.

Three artificial intelligence data challenges based on CT and MRI.

PURPOSE: The second edition of the artificial intelligence (AI) data challenge was organized by the French Society of Radiology with the aim to: (i), work on relevant public health issues; (ii), build large, multicentre, high quality databases; and (iii), include three-dimensional (3D) information and prognostic questions. MATERIALS AND METHODS: Relevant clinical questions were proposed by French subspecialty colleges of radiology. Their feasibility was assessed by experts in the field of AI. A dedicated platform was set up for inclusion centers to safely upload their anonymized examinations in compliance with general data protection regulation. The quality of the database was checked by experts weekly with annotations performed by radiologists. Multidisciplinary teams competed between September 11th and October 13th 2019. RESULTS: Three questions were selected using different imaging and evaluation modalities, including: pulmonary nodule detection and classification from 3D computed tomography (CT), prediction of expanded disability status scale in multiple sclerosis using 3D magnetic resonance imaging (MRI) and segmentation of muscular surface for sarcopenia estimation from two-dimensional CT. A total of 4347 examinations were gathered of which only 6% were excluded. Three independent databases from 24 individual centers were created. A total of 143 participants were split into 20 multidisciplinary teams. CONCLUSION: Three data challenges with over 1200 general data protection regulation compliant CT or MRI examinations each were organized. Future challenges should be made with more complex situations combining histopathological or genetic information to resemble real life situations faced by radiologists in routine practice.

Shear-wave elastography of the testicle: potential role of the stiffness value in various common testicular diseases.

AIM: To assess the value and efficacy of real-time shear-wave elastography (SWE) of normal testicular parenchyma and various common testicular diseases in clinical practice. MATERIALS AND METHODS: SWE was undertaken in 338 patients (mean age: 43.2±17.2 years, range 17-78 years) comprising normal testicles (n = 358), testicular microlithiasis (n = 40), and various testicular diseases (n = 208) and the stiffness was recorded. The final diagnosis was correlated with the clinical context, long-term follow-up, or histopathology. Statistical evaluation was performed to provide a stiffness threshold for pathological diagnosis. RESULTS: The mean size of testicular lesions was 2.6±1.5 cm (range: 10-42 mm). The mean Young's modulus value for normal testis was recorded at 4.55±2.54 kPa. Whatever the stage of microlithiasis, a higher statistically significant stiffness value was recorded. For acute orchitis, the mean stiffness value was slightly higher, but not statistically significantly. The testicular tumoural processes presented a median stiffness value of 21.02 kPa with a cut-off of 16.1 kPa. Fibrosis presented the highest median stiffness value of 30.03 kPa with a cut-off of 26.3 kPa. By analysing the distribution of the different pathological groups, the difference was statistically significant between fibrosis and tumoural processes (p = 0.001). CONCLUSION: SWE is a feasible technique in the exploration of the testicular parenchyma. SWE values can be used to differentiate testicular fibrosis from a tumoural process with confidence.

Impact of an ultrasound-guided radiofrequency ablation training program on the outcomes in patients with hepatocellular carcinoma.

PURPOSE: The aim of this study was to retrospectively evaluate the impact of a training program on the safety and efficacy of percutaneous ultrasound-guided radiofrequency ablation (RFA) for the treatment of hepatocellular carcinoma (HCC). MATERIALS AND METHODS: A total of 227 patients with 296 HCC nodules who underwent percutaneous RFA with or without transcatheter arterial chemoembolization at our institution were included. There were 163 men and 64 women with a mean age of 74.2±8.3 (SD) years (range: 41-89 years). Percutaneous ultrasound-guided RFA was performed by three trainees (205 HCC nodules in 157 patients) or a mentor (91 HCC nodules in 70 patients) after preprocedural preparation including planning ultrasonography. We compared background-related, tumor-related, and treatment-related factors, and local recurrence and complication rates between the trainee group and the mentor group. Similarly, we compared these variables among the years 2015, 2016, and 2017 for trainee group. RESULTS: The proportion of easy-to-treat tumors in the trainee group (109/205; 53.2%) was greater than that in the mentor group (33/91; 36.3%) (P=0.020). No significant differences were observed in procedure difficulty among the years 2015, 2016, and 2017 for trainee group (easy-to-treat HCC nodules: 25/47; 53.2% vs. 39/79; 49.4% vs. 45/79; 57.0%. P=0.775). The local recurrence rate in the trainee group was 8.8% (18/205 HCC nodules) which was equivalent to 7.7% in the mentor group (7/91 HCC nodules). No significant differences were observed in local recurrence rate (8.8% vs. 7.7%, respectively; P=0.621) and major complication rate (1.3% vs. 1.4%, respectively; P=0.999) between the trainee group and the mentor group. No significant differences were observed in local recurrence rates ([5/47; 10.6%] vs. [11/79; 13.9%] vs. [2/79; 2.5%]) (P=0.109) and major complication rates ([1/36; 2.8%] vs. [1/62; 1.6%] vs. [0/59; 0%]) (P=0.701) between the years 2015, 2016, and 2017 for trainee group. CONCLUSION: A well supervised training program that includes planning ultrasonography fosters the efficacy and treatment quality of RFA for HCC.

Ultra-low-dose unenhanced chest CT: Prospective comparison of high kV/low mA versus low kV/high mA protocols.

PURPOSE: To qualitatively and quantitatively compare unenhanced ultra-low-dose chest computed tomography (ULD-CT) acquired at 80kVp and 135kVp. MATERIALS AND METHODS: Fifty-one patients referred for unenhanced chest CT were prospectively included. There were 29 men and 22 women, with a mean age of 64.7±11.6 (SD) years (range: 35-91 years) and a mean body mass index of 26.2±6.3 (SD) (range: 17-54.9). All patients underwent two different ULD-CT protocols (80kVp-40mA and 135kVp-10mA). Image quality of both ULD-CT examinations using a 5-level scale as well as assessability of 6 predetermined lung parenchyma lesions were blindly evaluated by three radiologists and compared using a logistic regression model. Image noise of the two protocols was compared with Wilcoxon signed-rank test. RESULTS: The mean dose-length product at 80kVp and at 135kVp were 14.7±1.8 (SD) mGy.cm and 15.6±1.9 (SD) mGy.cm, respectively (P<0.001). Image noise was significantly lower at 135kVp (58.9±12.4) than at 80kVp (74.7±14.5) (P<0.001). For all readers and for all examinations, the 135kVp protocol yielded better image quality than 80kVp protocol, with a mean qualitative score of 4.5±0.7 versus 3.9±0.8 (P<0.001). The 135kVp protocol was significantly more often of diagnostic quality than the 80kvp protocol (92.3% versus 77.8%, respectively) (P<0.001) and was less prone to image quality deterioration in obese patients. Parenchymal lesions were never better depicted on the 80kVp protocol than with the 135kVp protocol. CONCLUSION: Unenhanced chest ULD-CT should be acquired at a high kilovoltage and low current, such as 135kVp-10mA, over a low kilovoltage and high current protocol.

Wide volume versus helical acquisition using 320-detector row computed tomography for computed tomography urography in adults.

PURPOSE: To evaluate the best collimation used in wide volume (WV) mode to cover the abdomen in computed tomography (CT) urography in terms of radiation dose and image quality. MATERIALS AND METHODS: This study was performed on a 320×0.5mm detector row CT unit. The first part identified the lowest volume CT dose index (CTDIvol) by using the topograms data of 25 medium size patients (13 men and 12 women; mean age: 52±9 [SD] years; age range: 46-68 years) using different collimations on WV from 6cm to 16cm and the one of the helical mode for the same coverage length. The second part consisted of a clinical evaluation of this result including 45 medium size patients (32 men and 13 women; mean age: 68±14 [SD] years; age range: 45-72 years). The qualitative evaluation included several items based on a 5-point Likert scale. RESULTS: The first part of the study indicated that a collimation of 10cm (200×0.5mm) in WV mode with 5 volumes had the lowest CTDIvol (2.78±0.35mGy; range: 2.35-3.21mGy) compared to helical mode (4.38±0.48mGy, range: 3.75-4.95mGy). In the second part, the mean radiation dose reduction by comparison with helical mode was 44.03%±0.36% (P<0.001) and 51.16%±1.22% (P<0.005) for CTDIvol and DLP, respectively. CONCLUSION: Wide volume mode of the abdomen can be performed with a significant radiation dose reduction with a collimation of 10cm (200×0.5mm) and five volumes.

Single source dual energy CT: What is the optimal monochromatic energy level for the analysis of the lung parenchyma?

OBJECTIVE: To determine the optimal monochromatic energy level for lung parenchyma analysis in spectral CT. METHODS: All 50 examinations (58% men, 64.8±16yo) from an IRB-approved prospective study on single-source dual energy chest CT were retrospectively included and analyzed. Monochromatic images in lung window reconstructed every 5keV from 40 to 140keV were independently assessed by two chest radiologists. Based on the overall image quality and the depiction/conspicuity of parenchymal lesions, each reader had to designate for every patient the keV level providing the best diagnostic and image quality. RESULTS: 72% of the examinations exhibited parenchymal lesions. Reader 1 picked the 55keV monochromatic reconstruction in 52% of cases, 50 in 30% and 60 in 18%. Reader 2 chose 50keV in 52% cases, 55 in 40%, 60 in 6% and 40 in 2%. The 50 and 55keV levels were chosen by at least one reader in 64% and 76% of all patients, respectively. Merging 50 and 55keV into one category results in an optimal setting selected by reader 1 in 82% of patients and by reader 2 in 92%, with a 74% concomitant agreement. CONCLUSION: The best image quality for lung parenchyma in spectral CT is obtained with the 50-55keV monochromatic reconstructions.

[What future for chest x-ray against ultra-low-dose computed tomography?] / Quel avenir pour la radiographie thoracique face au scanner ultra-low dose ?

Technological improvements, with iterative reconstruction at the foreground, have lowered the radiation dose of a chest CT close to that of a PA and lateral chest x-ray. This ultra-low dose chest CT (ULD-CT) has an image quality that is degraded on purpose, yet remains diagnostic in many clinical indications. Thus, its effectiveness is already validated for the detection and the monitoring of solid parenchymal nodules, for the diagnosis and monitoring of infectious lung diseases and for the screening of pleural lesions secondary to asbestos exposure. Its limitations are the analysis of the mediastinal structures, the severe obesity (BMI>35) and the detection of interstitial lesions. If it can replace the standard chest CT in these indications, all the more in situations where radiation dose is a major problem (young patients, repeated exams, screening), it progressively emerges as a first line alternative for chest radiograph, providing more data at a similar radiation cost.

[Progressive paralysis of the diaphragm following intra-abdominal chemotherapy]. / Paralysie diaphragmatique progressive consécutive à une chimiothérapie intra-abdominale.

INTRODUCTION: In patients presenting with intra-abdominal tumor and peritoneal carcinomatosis, cytoreductive surgery associated with hyperthermic chemotherapy may offer improved survival. We describe a case of diaphragmatic paralysis following that kind of procedure. CASE REPORT: A 60-year-old woman presented with respiratory insufficiency following cytoreductive surgery and intra-abdominal hyperthermic chemotherapy performed for pseudomyxoma intraperitonei. Pulmonary function assessment demonstrated a restrictive pattern. Three successive chest CT-scans demonstrated a thinning diaphragm muscle. Respiratory insufficiency eventually led to the death of our patient. CONCLUSION: We conclude in favor of a muscular degeneration of the diaphragm consecutive to the combined effect of cytoreductive surgery and intraperitoneal chemotherapy. Owing to the unusual nature of this complication, we did not consider it as a hypothesis at an early point in this patient's management. We think physicians should be aware of such a complication in order to consider it in a timely way. We recommend performing a biopsy of the diaphragm for pathology examination to assess muscular degeneration.

[Pre- and postoperative imaging of type B aortic dissection]. / Imagerie de la dissection aortique de type B : ce que veut savoir le chirurgien avant et après l'intervention.

Type B aortic dissections are serious diseases with a 60 to 80 % 5-year survival rate. Although typically managed with a medical treatment, surgery may be necessary in the acute/subacute or the chronic phase if significant complications are encountered. For these patients, CT angiography is the first-line imaging modality, used for indicating and preparing the surgical procedure as well as for follow-up. Physicians in charge of these patients should be familiar with the key reading points. Visceral malperfusion is the most common acute complication, while aneurysmal dilatation of the false lumen is the most common chronic complication, with surgical management generally indicated when the axial diameter of the aorta exceeds 55mm. Endovascular treatment tends to replace open surgery: it requires precise measurements and identification of the entry tear (contribution of 4D-MRA).

Five Year Outcomes of Surgical Treatment for Popliteal Artery Entrapment Syndrome.

OBJECTIVE/BACKGROUND: The aim of this study was to evaluate long-term outcomes following surgery for popliteal artery entrapment syndrome. METHODS: A retrospective study of all patients that underwent surgery for popliteal artery entrapment syndrome between January 2003 and December 2009 was performed. Patient demographic data, clinical features, imaging modalities, and surgical management were recorded. The primary outcome was 5 year patency. RESULTS: Eighteen patients (25 limbs) underwent surgery. The mean age at the time of surgical procedure was 35 (median 35 years; range 15-49). Presentation was bilateral in seven patients (39%). Diagnosis was made using various imaging modalities, including position stress test, Duplex ultrasonography, computed tomography angiography, magnetic resonance imaging and conventional angiography. In four limbs the popliteal artery was compressed and undamaged (16%), and treatment consisted of musculo-tendinous division alone. In 16 limbs the popliteal artery was damaged with lesions limited to the popliteal artery (64%) where treatment consisted of venous interposition. In five limbs lesions extended beyond the popliteal artery (20%) and procedures included one below knee femoro-popliteal bypass, three femoro-posterior tibial bypasses, and one popliteo-posterior tibial bypass. Musculo-tendinous division was associated with vascular reconstruction in 19 limbs (90%). Mean follow up was 82 months (median 81 months, range 60-120). Five year patency was 84%. CONCLUSION: Long-term outcomes of surgical procedures performed for popliteal artery entrapment syndrome can be considered satisfactory.

[Multimodal imaging of ischemic heart diseases: A 2015 update]. / Imagerie multimodale des cardiopathies ischémiques : possibilités et indications en 2015.

Current realities and future possibilities of imaging in the ischemic heart diseases are very broad and constantly evolving, with the improvement of existing technologies and the introduction of new features such as dual-energy CT, strain ultrasound, multimodality fusion or perfusion MRI. Regular collaboration between prescribing clinicians, cardiologists, radiologists and nuclear radiologists is therefore essential to tailor the examination to the specific clinical question. The indications for each modality will therefore depend on its diagnostic performance, cost, acquisition and post-processing times and eventual radiation exposure. This review will detail principles and applications of current cardiac imaging examinations: echocardiography, nuclear medicine, MRI, CT and coronary angiography, emphasizing their current strengths and weaknesses in the ischemic heart diseases management.

Herpes simplex virus 2 hepatitis in a lung transplant recipient: a diagnostic challenge.

Herpes simplex virus (HSV) hepatitis is a rare and serious complication in immunocompromised patients. We report the case of an HSV hepatitis occurring 4 years after lung transplantation in a cystic fibrosis patient. The presentation was nonspecific, mimicking acute cholecystitis; orogenital signs were absent. The diagnosis was made based on viral cultures performed during cholecystectomy and confirmed by blood quantitative polymerase chain reaction. Although the diagnosis and treatment were delayed, the patient fully recovered with acyclovir, reduced immunosuppression, and intravenous immunoglobulins. The diagnostic difficulties, prognostic factors, and treatments of this infection are discussed.