[Renal artery stenosis long time after renal denervation for resistant hypertension]. / Sténose de l'artère rénale à distance d'une dénervation rénale pour HTA résistante.

The onset of renal artery stenosis following a renal denervation is rare and occurs in the first few months after renal denervation. We report the onset of renal artery stenosis a long time after the renal denervation for resistant hypertension. This is a 74 year-old patient who stopped smoking in 1980 and who was treated for dyslipidemia with a revascularized coronary artery disease in 2011, a well-stabilized peripheral arterial disease since 2001, a stable asymptomatic carotid atheroma and a good kidney function. His hypertension known since 1995 became resistant. After the control of renal arteries by angio-CT scan, he had a renal denervation in October 2012. His blood pressure decreased 3 months later confirmed by self-blood pressure monitoring (SBPM) and ambulatory blood pressure monitoring (ABPM) with a CT scan with a non-significant renal artery stenosis in January 2014. He remained normotensive under treatment until July 2015 but his hypertension became uncontrolled at the end of 2015 then resistant and severe confirmed by SBPM in April 2017, despite a 5-drug antihypertensive treatment associated to atorvastatin and clopidogrel confirmed by SBPM in April 2017. A left post-ostial renal artery stenosis with decrease in size of left kidney and cortex as compared to 2011 was detected at CT and treated by angioplasty. It was associated with a rapid decrease in blood pressure but unfortunately a new increase related to a restenosis occurred at the end of 2017, which justified a new angioplasty. Discussion about the etiology and the management of this renal post-denervation late stenosis.

CT-scan images preprocessing and segmentation to improve bioprosthesis leaflets morphological analysis.

The visualization of bioprosthesis leaflet morphology might help to better understand the underlying mechanism of dysfunction in degenerated aortic bioprosthesis. Because today such visualization of bioprosthesis leaflet morphology is intricate to impossible with other imaging techniques, we hypothesized that the processing of multi-detector CT images would allow better visualization of the prosthetic valve leaflets after biological aortic valve replacement. The purpose of our study was to prospectively evaluate patients with a degenerated aortic bioprosthesis, waiting for reoperation, by using 64-slice CT to evaluate prosthetic leaflets morphology. A semi-automatic segmentation of pre-operative tomodensitometric images was conducted, using 2 different implementations of the region growing algorithm. Here we report all segmentation steps (selection of the region of interest, filtering, segmentation). Studied degenerated aortic bioprostheses were represented by two Carpentier-Edwards Supra Annular Valve (porcine leaflets), one Edwards Perimount (pericardial leaflets) and one Medtronic Mosaic (porcine leaflets). Both segmentation methods (Isotropic Region Growing and Stick Region Growing) allowed a semi-automatic segmentation with 3D reconstruction of all bioprosthetic components (stent, leaflets, degeneration/calcifications). Explanted bioprosthesis CT images were also processed and used as reference. Segmentation results were compared by means of quantitative criteria. Semi-automatic segmentation using region growing algorithm seems to provide an interesting approach for the morphological characterization of degenerated aortic bioprostheses. We believe that in the next future CT scan images segmentation may play an important role to better understand the mechanism of dysfunction in failing aortic bioprostheses. Moreover, bioprostheses 3D reconstructions could be integrated into preoperative planning tools to optimize valve-in-valve procedure.

[Acute aortic syndrome: CT imaging features]. / Comment j'explore une suspicion de syndrome aortique aigu au scanner.

Acute aortic syndromes include aortic dissection, intramural thrombus, and penetrating atherosclerotic aortic ulcer. These are potentially life-threatening abnormalities of the aorta requiring immediate evaluation by the cardio-thoracic surgery service. CT angiography is the most appropriate imaging modality in the acute setting to detect and diagnose the disease and assess its severity. Precontrast and postcontrast imaging should be obtained of the entire aorta from thorax to pelvis. After aortic rupture, the most severe complication is visceral ischemia from hypoperfusion. Dissections should be systematically searched for and may be amenable to endovascular treatment.

[Stent-graft treatment of the descending thoracic aorta in high risk patients]. / Traitement par stent grafts des pathologies de l'aorte thoracique descendante.

PURPOSE: To report our experience with endovascular stent-graft repair of descending thoracic aorta diseases in high risk patients. MATERIALS AND METHODS: Between 2000 and 2007, 49 high surgical risk patients (mean age: 64.6 years) underwent stent-graft placement, including 24 cases presenting acutely. Mean follow-up was 25.4 months. Etiologies included 15 aneurysms, 11 dissections, 10 penetrating ulcers, 9 false aneurysms, 2 ruptures of the aortic isthmus, 2 intramural hematomas. RESULTS: Access failure occurred in one patient. The overall mortality was 27.1% (n=13), nine related to the presenting pathology or treatment. Thirty-day mortality was 10.4% (n=5). Complications included vascular injury at the iliac or femoral artery access (10.2%), 1 case of flaccid paraplegia, 2 cases of transient paraparesis, 2 strokes, 2 stent migrations and 1 stent rupture. The rate of early endoleak was 39.6% while the rate of delayed endoleak was 14.6%. Seven patients (14.6%) required repeat endovascular interventions. Explantation was required in 2 cases. The latest available follow-up showed no lesion enlargement in 70.7% (n=29/41) of our patients. CONCLUSION: Descending thoracic aortic pathology can be treated using endografts in high risk patients, although significant morbidity and mortality remain. Because of the high rate of endoleaks, close follow-up is required.

[Bilateral traumatic dissection of the renal arteries]. / Dissection bilatérale traumatique des artères rénales.

The bilateral dissection of the renal arteries is uncommon after blunt trauma. The clinical symptoms are scarce and inconstant. The diagnosis is based on contrast-enhanced computed tomography with intravenous contrast and angiographic examination is required only if an endovascular revascularization is envisaged. We reported here, an exceptional case of bilateral traumatic dissection of the renal arteries associated with acute renal failure. The delayed revascularization does not allow the recuperation of a renal function.

Plaque density on CT, a potential marker of ischemic stroke.

The authors sought to determine in a retrospective analysis whether carotid plaque soft TD on CT is associated with recent ischemic neurologic events. Among 141 patients (99 asymptomatic), 106 plaques with more than 50% stenosis were selected for density measurements. They found an odds ratio for neurologic events associated with a 10-point decrease in density of 1.54 (p = 0.002), showing an association between plaque density and neurologic events.

[Renal arteriovenous fistula associated with fibromuscular dysplasia of the renal arteries]. / Fistule artérioveineuse rénale associée a une dysplasie fibromusculaire des artères rénales.

Three to 5% of hypertensive diseases have a renovascular origin. Atherosclerosis and fibromuscular dysplasia are the two major causes of renovascular hypertension. Association of renal arteriovenous fistula and fibromuscular dysplasia is uncommon. The authors propose to illustrate the usefulness of Doppler ultrasonography and digital subtraction angiography in the diagnostic and therapeutic management of a renal arteriovenous fistula associated with fibromuscular dysplasia discovered after severe preeclampsia in a 30 year-old woman.

Two cases of 'asthma' revealing a diverticulum of Kommerell.

Among embryonic aortic vascular malformations, persistence of a right aortic arch and aberrant left subclavian artery associated with a diverticulum of Kommerell is rare, and is estimated to occur in 0.1% of the general population. We report two cases of diverticulum of Kommerell in which tracheal compression due to the vascular ring induced respiratory symptoms such as asthmatic dyspnoea. This reminds us that at least a chest X-ray should be performed in newly diagnosed asthmatic patients, focusing on the trachea and upper mediastinum. In case of vascular abnormality, angiography and magnetic resonance are the best investigations to define the abnormal anatomy and guide surgery.

[Coronary steal syndrome by systemic pulmonary hypervascularization fed by a mammary-left anterior descending artery bypass. Treatment by embolization]. / Vol coronarien par hypervascularisation systémique pulmonaire alimentée par un pontage mammaire--interventriculaire antérieure. Traitement par embolisation.

We report a case of coronary-steal syndrome which occurred after coronary bypass surgery. It was related to systemic hypervascularization of the lung caused by a bronchopathy. The steal syndrome was fed by an ectopic bronchial artery arising from the internal mammary--left anterior descending artery bypass graft. The myocardial ischemia disappeared after hyperselective embolization of the ectopic bronchial artery. The authors outline the rarity of this syndrome and its pathophysiology. They insist on the necessity to perform broncho-systemic arteriography for candidates to coronary surgery, in patients with thoracic diseases which can induce systemic hypervascularization of the lung.

The RETAIN project: DICOM teleradiology over an ATM-based network. Radiological Examinations Transfer on an ATM Integrated Network.

The RETAIN project (Radiological Examinations Transfer on an ATM Integrated Network) has aimed at testing videoconferencing and DICOM image transfers to get advice about difficult radiological cases over an asynchronous transfer mode (ATM)-based network, which affords a more comfortable interface than narrow-band networks and allows exchange of complete image series using the DICOM format of studies. For this purpose, an experimental ATM network was applied between six university hospitals in four different countries. An assessment of the functionalities of the system was performed by means of log-file analysis, video recording of the sessions and forms filled out by the participants at the end of each session. Questionnaires were answered by the users at the end of the project to bring out perspectives of utilisation and added value. We discussed 43 cases during 20 sessions. For technical or organisational problems, only 20 of the 36 planned sessions took place. The throughput over ATM (10.5 Mbit/s, 20 times faster than six ISDN B-channels) was adequate. Despite the experimental configuration of the network, the system was considered as satisfactory by all the physicians. In 72 % of the sessions, the expected result (answer to the question) was gained. By common consent, videoconferencing was unanimously regarded as a prominent tool in improving the interaction quality. Asynchronous transfer mode is an efficient method for fast transferring of radiologic examinations in DICOM format and for discussing them through high-quality videoconferencing.

Influence of the teleradiology technology (N-ISDN and ATM) on the inter-hospital management of neurosurgical patients.

We set out to assess the influence of a teleradiology network on the relations between a general hospital and a 100 km distant university hospital in the context of neurosurgical emergencies, and compared a commercially available technology, N-ISDN (Narrowband Integrated Service/Digital Network), to an emerging technology, ATM (Asynchronous Transfer Mode). The evaluation was conducted using records of advice request calls and patient transfers. Three phases were considered: without teleradiology, with transfer of digitized images over N-ISDN at 64 kbps, and with an experimental ATM network at 10.5 Mbps with DICOM image transfers and videoconferencing. Additionally, staff meetings over ATM videoconferencing were set up. To assess the ATM service, we used log files and questionnaires, 108 advice requests were studied over a 18 month period. The average transmission time for one examination was 38 s with full DICOM image resolution over ATM, versus 150 s with 10:1 JPEG (Joint Photographic Expert Group) compression over N-ISDN. Up to 50% unnecessary patient transfers were avoided. Advice requests increased fourfold, and non-urgent advice requests increased from 0 to 21%. Despite the experimental configuration of the ATM network, the service gave satisfaction to all the physicians. Videoconferencing was unanimously regarded as a prominent tool to improve the quality of interaction. It was particularly useful for non-urgent cases and distant staff meetings. Teleradiology can improve the relations between hospitals through an increase of urgent and non-urgent advice requests. Asynchronous transfer mode is an efficient way for fast transfer of radiological examinations in DICOM format and for discussing them through high-quality videoconferencing.

Analysis of cerebrovascular diseases by a new 3-dimensional computerised X-ray angiography system.

We set out to validate the concept of three-dimensional (3D) angiography. We evaluated the sensitivity and the quality of morphological analysis mode possible by an experimental system for imaging cerebrovascular disease versus standard digital subtraction angiography (DSA). The system, the 3D Morphometer, is a computerised X-ray angiography unit capable of acquiring a set of two-dimensional (2D) projections during a rotation and then reconstructing a 3D volume from them. We studied 78 patients with suspected cerebrovascular disease. 3D and 2D images (standard 2D DSA performed during the same procedure), were reviewed blindly to assess detection and display of morphological characteristics of cerebrovascular diseases. We found 53 aneurysms, 22 arteriovenous malformations and two venous angiomas. On 3D angiography we detected two aneurysms we missed on 2D angiography. In 47 aneurysms on which further data were obtained during surgery or embolisation, the 3D angiography allowed more accurate analysis of the neck and surrounding vessels in cases in which the 2D angiographic findings were doubtful. Assessment of arteriovenous malformations was equivalent with both techniques. Under the conditions of our study, the technical constraints being the same for both methods, 3D angiography was superior to 2D angiography. Implementation on C-arm vascular systems is being evaluated.

Prospective randomized trial of chemoembolization versus intra-arterial injection of 131I-labeled-iodized oil in the treatment of hepatocellular carcinoma.

Intra-arterial injection of radioactive Lipiodol has shown promising results in patients with hepatocellular carcinoma (HCC) and portal obstruction. The aim of this prospective, randomized trial was to compare the efficacy and tolerance of 131I-labeled Lipiodol and chemoembolization for the treatment of patients with HCC. From September 1990 to September 1993, 142 patients (135 men, 7 women; age: 65 +/- 6.6 years) were randomly assigned to treatment groups and given either intra-arterial injections of 131I-labeled Lipiodol (60 mCi; 2.2 GBq) (n = 73) or chemoembolization (70 mg cisplatin) (n = 69). Subsequent injections were given at 2, 5, 8, 12, and 18 months. Tumor response was assessed on the basis of tumor size and serum alpha-fetoprotein levels. Patient tolerance was assessed clinically and angiographically. Survival rate was the main end-point. A total of 129 patients (65 in the 131I-labeled Lipiodol group and 64 in the chemoembolization group) were available for analysis; 13 were excluded, mainly because of portal vein thrombosis. The two groups were comparable. Actuarial survival curves were not significantly different between the two groups. Overall survival rates at 6 months, 1, 2, 3, and 4 years were 69%, 38%, 22%, 14%, and 10%, and 66%, 42%, 22%, 3%, and 0% in the 131I-labeled Lipiodol and chemoembolization groups, respectively. Reduction in tumor size was similar for the two groups, with complete response in 1 and 0 patients and partial response in 15 and 16 patients in the 131I-labeled Lipiodol and chemoembolization groups, respectively. Tolerance was significantly better in the 131I-labeled Lipiodol group both clinically (3 severe side effects vs. 29 in the chemoembolization group; P < .001) and angiographically (1 arterial thrombosis vs. 10 in the chemoembolization group; P < .01). In terms of patient survival and tumor response, radioactive 131I-labeled Lipiodol and chemoembolization were equally effective in the treatment of HCC, but tolerance to 131I-labeled Lipiodol was significantly better.

[Test of a teleradiology network based on ATM (asynchronous transfer mode)]. / Essai d'un réseau de téléradiologie basé sur ATM (asynchronous transfer mode).

The retain project (Radiological Examination Transfer on ATM Integrated Network) consisted in teleradiology trials focused on pediatric imaging between two university hospitals. Rennes (France) and Barcelona (Spain) using an integrated broadband communication network based on ATM (asynchronous transfer mode), as part of a European research program. The network used was a full 10 Mbits/s ATM network directly connected to local PACSs (medical imaging hospital networks). One important reason to explicitly consider ATM for medical imaging is that multimedia applications on such networks allow integration of digital data and person-to-person communication. The utility of broadband communication for teleradiology has been confirmed. High quality video and sound are important for both human communication and medical video transfer. The project led to guidelines regarding technical options still open to improvement.

Hemochromatosis: diagnosis and quantification of liver iron with gradient-echo MR imaging.

PURPOSE: To assess the role of magnetic resonance (MR) imaging in detection and quantification of liver iron overload. MATERIALS AND METHODS: MR imaging at 0.5 T was prospectively performed on 77 patients (67 with liver iron overload and 10 without) who underwent a liver biopsy with biochemical determination of the liver iron concentration (LIC) (normal, < 36 mumol per gram of liver tissue [dry weight]). Ratios of signal intensities and liver T2 relaxation time were calculated from images obtained with spin-echo and breath-hold gradient-echo (GRE) sequences. RESULTS: Liver-to-tissue signal intensity ratios were better correlated with LIC than T2 relaxation time. Long-echo-time GRE sequences were the most sensitive for detection of slight overload. Thus, high sensitivity (94%) and specificity (90%) were obtained with a liver-to-fat ratio threshold of 1. The quantification of iron with MR imaging was accurate when the LIC was 80-300 mumol/g. For heavy overload, above 300 mumol/g, quantification was impossible owing to complete signal loss. Pancreatic and splenic signal intensity were unchanged in most cases. CONCLUSION: This method, which can be improved by using more sensitive sequences with a high-field-strength system, should be competitive with biopsy for the diagnosis of substantial liver iron overload.

MR lymphography: study of a high-efficiency lymphotrophic agent.

PURPOSE: To investigate the utility of a monocrystalline iron oxide nanoparticle (MION) as a contrast agent in magnetic resonance (MR) imaging of lymph nodes. MATERIALS AND METHODS: Pharmacokinetic data were obtained in rats after intravenous, subcutaneous, and intraarterial injection of indium-111-MION-46. MR imaging was performed to determine optimal dosages and pulse sequences in rats. Models of lymph node metastasis in rabbits and lymph node hyperplasia in rats were used to demonstrate the efficacy of MION in differentiation of malignant and benign adenopathies. RESULTS: Biokinetic data indicate that nodal accumulation occurs primarily after extravasation of agent into the interstitial space (slow component) and subsequent trapping by lymph node macrophages (fast component). Relatively low concentrations (15-25 mumol Fe per kilogram for peripheral nodes after intraarterial injection) decrease signal intensity of nodes at MR imaging. CONCLUSIONS: Lymph node accumulation of MION-46 is high. Modification of injection techniques that alter capillary permeability allows use of systemically administered agent at doses as low as 15-25 mumol Fe per kilogram.

[Station of interpretation]. / Station d'interprétation.

Revisualization or image processing stations are constantly improving, but they have not yet been designed to replace the x-ray display unit for the interpretation of films. An improvement of the integration of these stations within the hospital computer system and functional enrichment must be achieved in order to prepare for the "digital" era. Although this prospect is not for the immediate future, it is important to develop tomorrow's tools with a minimum of intelligence to facilitate their acceptance.

Magnetic resonance imaging and assessment of liver iron content in genetic hemochromatosis.

Computed tomography (CT) scanning is not highly sensitive in the assessment of liver iron content and magnetic resonance imaging (MRI) appears to be more efficient. The aim of this study was to determine the effectiveness of MRI in the evaluation of liver iron content using a standard spin-echo technique. The study included 23 patients with genetic hemochromatosis and 24 non-iron-overloaded patients as controls. A comparison was made of: (a) MRI signal intensity of liver, spleen, paravertebral muscles and subcutaneous adipose tissue using two different spin-echo sequences (SE 500/28; SE 2000/28,56); (b) liver attenuation determined by a single energy CT scan; and (c) a biochemical determination of hepatic iron. There was a significant decrease in liver signal intensity in the genetic hemochromatosis group (256 +/- 201, mean +/- S.D.) compared with the control group (801 +/- 413, p less than 0.001), but there was no correlation with liver iron concentration. However, such a correlation was found and was even more highly significant than in CT when the ratio between the liver and another organ was taken into account. For a lower limit of liver/spleen ratio calculated at 0.46 (mean 2 S.D. in the control group), the specificity (0.96) of MRI was satisfactory, but the sensitivity (0.78) remained insufficient (MRI being unable to detect an iron overload of up to 125 mumol/g). Hopefully, these results might be improved in the near future by using more sensitive sequences such as gradient echo sequences.