Performance of four dual-energy CT platforms for abdominal imaging: a task-based image quality assessment based on phantom data

OBJECTIVES

To compare the spectral performance of dual-energy CT (DECT) platforms using task-based image quality assessment based on phantom data.

MATERIALS AND METHODS

Two CT phantoms were scanned on four DECT platforms: fast kV-switching CT (KVSCT), split filter CT (SFCT), dual-source CT (DSCT), and dual-layer CT (DLCT). Acquisitions on each phantom were performed using classical parameters of abdomen-pelvic examination and a CTDI_vol at 10 mGy. Noise power spectrum (NPS) and task-based transfer function (TTF) were evaluated from 40 to 140 keV of virtual monoenergetic images. A detectability index (d') was computed to model the detection task of two contrast-enhanced lesions as function of keV.

RESULTS

The noise magnitude decreased from 40 to 70 keV for all DECT platforms, and the highest noise magnitude values were found for KVSCT and SFCT and the lowest for DSCT and DLCT. The average NPS spatial frequency shifted towards lower frequencies as the energy level increased for all DECT platforms, smoothing the image texture. TTF values decreased with the increase of keV deteriorating the spatial resolution. For both simulated lesions, higher detectability (d' value) was obtained at 40 keV for DLCT, DSCT, and SFCT but at 70 keV for KVSCT. The detectability of both simulated lesions was highest for DLCT and DSCT.

CONCLUSION

Highest detectability was found for DLCT for the lowest energy levels. The task-based image quality assessment used for the first time for DECT acquisitions showed the benefit of using low keV for the detection of contrast-enhanced lesions.

KEY POINTS

• Detectability of both simulated contrast-enhanced lesions was higher for dual-layer CT for the lowest energy levels. • The image noise increased and the image texture changed for the lowest energy levels. • The detectability of both simulated contrast-enhanced lesions was highest at 40 keV for all dual-energy CT platforms except for fast kV-switching platform.

Noise assessment across two generations of iterative reconstruction algorithms of three manufacturers using bone reconstruction kernel

PURPOSE

To compare the noise-magnitude and noise-texture obtained using strong kernel across two generations of iterative reconstruction (IR) algorithms proposed by three manufacturers.

MATERIALS AND METHODS

Five computed tomography (CT) systems equipped with two generations of IR algorithm (hybrid/statistical IR [H/SIR] or full/partial model-based IR [MBIR]) were compared. Acquisitions on Catphan 600 phantom were performed at 120kV and three dose levels (CTDI_vol: 3, 7 and 12mGy). Raw data were reconstructed using standard "bone" kernel for filtered back projection and one iterative level of two generations of IR algorithms. Contrast-to-noise ratio (CNR) was computed using three regions of interest placed semi-automatically: two placed in the low-density polyethylene and Teflon inserts and another placed on the solid water. Noise power spectrum (NPS) was computed to assess the NPS-peak and noise-texture.

RESULTS

CNR was significantly greater in MBIR compared to H/SIR algorithms for all CT systems (P<0.01). CNR were improved on average from H/SIR to MBIR of 36±14% [SD] (range: 24-57%) for GE-Healthcare, 109±19 [SD] % (range: 89-139%) for Philips Healthcare and 42±5 [SD] % (range: 36-47%) for Siemens Healthineers. The mean NPS peak decreased from H/SIR to MBIR by -41±6 [SD] % (range: -47--35%) for GE Healthcare, -79±3 [SD] % (range: -82--76%) for Philips Healthcare and -52±2 [SD] % (range: -54--51%) for Siemens Healthineers systems. NPS spatial frequencies were greater with MBIR than with H/SIR for Philips Healthcare (20 ± 2 [SD] %; range: 19-22%) and for Siemens Healthineers (9±5 [SD] %; range: 4-14%) but lower for GE Healthcare (-17±3 [SD] %; range: -14--20%).

CONCLUSION

Using bone kernel with recent MBIR algorithms reduces the noise-magnitude for all CT systems assessed. Noise texture shifted towards high frequency for Siemens Healthineers and Philips Healthcare but the opposite for GE Healthcare.

PICC management led by technicians: Establishment of a cooperation program with radiologists and evaluation of complications

PURPOSE

The purpose of this study was to evaluate a cooperation program in order to compare incidence of complications after peripherally inserted central catheter (PICC) placement between radiologists and technicians.

MATERIALS AND METHODS

PICC placement technique was standardized with ultrasound-guided puncture and fluoroscopic guidance. Numbers of PICC delegated to technicians, and PICC placement difficulties, were prospectively recorded for the whole study population whereas complications such as PICC infection, deep venous thrombosis and catheter occlusion were prospectively recorded until PICC removal for a subgroup of patients included during one month.

RESULTS

A total of 722 patients had PICC placement. There were 382 men and 340 women with a mean age of 66.8±15.8 (SD) years (range: 18-94years); of these, 442/722 patients (61.22%) were included in the cooperation program with 433/722 patients (59.97%) who effectively had PICC placement by technicians and 289/722 (40.03%) by radiologists. Technicians needed radiologists' help for 23/442 patients (5.20%) including 6 failed PICC placement subsequently performed by radiologists. Twenty complications (20/77; 26%) were recorded in the subgroup of 77 patients studied for complications. No differences in complications rate were found between the 33 patients who underwent PICC placement by radiologists (6/33; 18%) and the 44 patients who underwent PICC placement by technicians (14/44; 32%) (P=0.296). Complications included 8 PICC-related infections (8/77; 10.4%), 3 deep venous thromboses (3/77; 3.9%) and 9 catheter occlusions (9/77; 11.7%).

CONCLUSION

PICC placement led by technicians is feasible and safe without statistical difference in terms of complications compared to PICC placement made by radiologists.

Assessment of Patient's Peak Skin Dose Using Gafchromic Films During Interventional Cardiology Procedures: Routine Experience Feedback

To assess the interest of Gafchromic films in detection of patient's peak skin dose (PSD) in interventional cardiology. A prospective study of 112 patients was conducted (July-December 2015). Three diagnostic and therapeutic procedures were evaluated: coronary angiography (CA), coronary angiography and coronary angioplasty for one or two vessels disease (CA-PTCA) and coronary angioplasty of complex chronic total occlusion (CTO). Dosimetric indicators (DIs) were collected and PSD were measured with Gafchromic films. Dose distribution was evaluated within 10 'Thorax Body-zone' defined by the system. Correlations between PSD and DI or dose distribution were computed. Delivered dose increased in complex procedures. The PSD were 0.121 ± 0.063 Gy for CA, 0.256 ± 0.142 Gy for CA-PTCA and 1.116 ± 0.721 Gy for CTO. High correlations were observed for PSD and DI as well for dose distribution within the 'Thorax Body-zone'. Film dosimetry is suggested for CTO procedures since the threshold of 2 Gy for skin injuries is likely to be exceeded.

Imaging of tumors and tumor-like lesions of the knee

Tumors and tumor-like lesions of the knee are common conditions. Because the synovial membrane covers a large part of the knee, tumors and tumor-like lesions of the knee are mostly synovial. Magnetic resonance imaging (MRI) plays a major role in the assessment and characterization of these lesions. However, the diagnostic approach of these lesions must be performed systematically. First, the lesion must be precisely located, and then the anatomical structure involved must be determined. Finally, clinical background that includes the age of the patient, frequency of the disease and, if any, associated signs as well as MRI characteristics must be analyzed. In this review, we describe the anatomy of the knee and its compartments and provide a description of the main tumors and tumor-like lesions of the knee. We present a diagnostic approach based on the location within the knee of the lesions and the anatomical structures involved.

Diffusion-weighted MRI, dynamic susceptibility contrast MRI and ultrasound perfusion quantification of denervated muscle in rabbits

OBJECTIVE

The purpose of this study was to assess denervated muscle perfusion using dynamic susceptibility contrast MRI (DSCMRI) and contrast-enhanced ultrasound (CEUS), and to measure denervated muscle apparent diffusion coefficient (ADC) on b1000 diffusion-weighted MRI (DWMRI) at 3 T in order to clarify whether muscle denervation leads to an increase in the extracellular extravascular space, or an increase in blood flow-or both.

MATERIALS AND METHODS

Axotomy of the right sciatic nerve of six white rabbits was performed at day 0. At day 9, hind limb muscles MRI and CEUS were performed to assess the consequences of denervation and both semimembranosus muscles of each rabbit were explanted for histological studies. Signal intensity on T2- and T1-weighted MRI, ADC on DWMRI, maximum signal drop (MSD) on DSCMRI and the area under the curve (AUC) on CEUS were measured over circular regions of interest (ROI), in both semimembranosus muscles. Non-parametric Wilcoxon matched-pairs tests were used to assess the mean differences between denervated and normal muscles.

RESULTS

T2 fat-saturated (FS) MRI studies showed a strong signal in the right semimembranosus muscles compared with the left side, and gadolinium enhancement was observed on T1 FS MRI. Denervated muscles show a significant increase in ADC on DWMRI (p < 0.01) and a significant signal enhancement on DSCMR imaging (p < 0.05) and on first-pass CEUS (p < 0.05).

CONCLUSION

The results of this study--based on perfusion- and diffusion-weighted images--suggest that, after denervation, both increased blood flow through muscle tissue and expansion of the extracellular water volume are present.

[Ankle brachial index measurement at the first visit for hypertension: a safe and very useful tool for aortic coarctation screening. A case report]

A 24-year-old African who had been living in France for few years first consulted at our institution for severe systemic hypertension. He had no prior medical or surgical history. The patient was strictly asymptomatic. Except for systemic hypertension at both arms, the basic physical examination was normal with no cardiac murmur and no pulse deficit. A 24-hour ambulatory blood pressure monitoring performed before the consultation confirmed the presence of systemic hypertension with a mean blood pressure at 155/90mmHg during the day and also during the night under anti-hypertensive treatment. Ankle-brachial index measurement was low at 0.8 at both legs. Subsequently, a trans-thoracic echocardiography (TTE) and an aortic CT-scanner were performed. The TTE did not find any abnormalities including no aortic dilatation or no ventricular hypertrophy. The CT-scanner revealed a partial aortic coarctation. The patient underwent aortic surgery and recovered in few days with quite normal blood pressure under medical treatment. In conclusion, systematic ankle-brachial index is useful and recommended in every patient at first visit for systemic hypertension. Its safety and simplicity make it an essential tool in the management of systemic hypertension especially in populations with no systematic screening of aortic coarctation in childhood. It was in the present case very useful for the final diagnosis and treatment. In addition, it is an efficient tool to screen patients with asymptomatic peripheral artery disease and it can help for stratification of cardiovascular risk.

[Virtual interventional radiology: evaluation of performances as a function of experience]

PURPOSE

To determine the value of an angioplasty simulation to differentiate the users based on their level of experience. To determine the perceived usefulness of an angioplasty simulation program.

MATERIALS AND METHODS

Forty-six radiologists performed a renal angioplasty on a VIST simulator (Mentice Corporation, Gothenburg, Sweden); the procedure was completed by 41 radiologists. The radiologists were divided into two groups based on the level of experience. Quantitative variables analyzed included procedure duration time and fluoroscopy time. The radiologists then completed a questionnaire evaluating the simulation program.

RESULTS

Radiologists with more than 2 years of clinical experience (n=14) performed the procedures faster (20.4 min vs 27.4 min, p<0.01) using less fluoroscopy time (7.8 min vs 11.2 min, p<0.05) than others. Radiologists performing more than 2 procedures per month (n=14) performed the procedures faster (19.4 min vs 27.9 min, p<0.01) using less fluoroscopy time (7.4 min vs 11.3 min, p<0.05) than other (n=27). The participating radiologists indicated that the simulation was realistic.

CONCLUSION

Procedure duration time and duration of fluoroscopy were criteria able to differentiate the users based on their level of experience. The educational value of the simulation program was perceived as helpful by the users.

[Contrast enhanced MR angiography: evolving towards whole-body real time acquisitions]

MRA includes all techniques used to depict vessels with MR. Gadolinium contrast injection combined with gradient echo sequences is the technique of choice for vascular imaging. Technical advances now allow faster acquisitions. The purpose of this article is to present two main advances with MRA: whole-body MRA and dynamic 3D MRA. Technical considerations, acquisition techniques, advantages and pitfalls based on our experience with a 1.5T MR unit will be discussed in order to promote their use in routine clinical practice.

Prevalence of peripheral arterial disease in high-risk patients using ankle-brachial index in general practice: a cross-sectional study

AIMS

The deleterious nature of peripheral arterial disease (PAD) is compounded by a status of underdiagnosed and undertreated disease. We evaluated the prevalence and predictive factors of PAD in high-risk patients using the ankle-brachial index (ABI).

METHODS

The ABI was measured by general practitioners in France (May 2005-February 2006) in 5679 adults aged 55 years or older and considered at high risk. The primary outcome was prevalence of PAD (ABI strictly below 0.90).

RESULTS

In all, 21.3% patients had signs or symptoms suggestive of PAD, 42.1% had previous history of atherothrombotic disease and 36.6% had two or more cardiovascular risk factors. Prevalence of PAD was 27.8% overall, ranging from 10.4% in patients with cardiovascular risk factors only to approximately 38% in each other subgroup. Prevalence differed depending on the localization of atherothrombotic events: it was 57.1-75.0% in patients with past history of symptomatic PAD; 24.6-31.1% in those who had experienced cerebrovascular and/or coronary events. Regarding the classical cardiovascular risk factors, PAD was more frequent when smoking and hypercholesterolemia history were reported. PAD prevalence was also higher in patients with history of abdominal aortic aneurysm, renal hypertension or atherothrombotic event. Intermittent claudication, lack of one pulse in the lower limbs, smoking, diabetes and renovascular hypertension were the main factors predictive of low ABI.

CONCLUSIONS

Given the elevated prevalence of PAD in high-risk patients and easiness of diagnosis using ABI in primary care, undoubtedly better awareness would help preserve individual cardiovascular health and achieve public health goals.

Cardiac magnetic resonance imaging in systemic sclerosis: a cross-sectional observational study of 52 patients

Objectives:

To assess the prevalence and patterns of cardiac abnormalities as detected by cardiac magnetic resonance imaging (MRI) in systemic sclerosis (SSc).

Methods:

Fifty-two consecutive patients with SSc underwent cardiac MRI to determine morphological, functional, perfusion at rest and delayed enhancement abnormalities.

Results:

At least one abnormality on cardiac MRI was observed in 39/52 patients (75%). Increased myocardial signal intensity in T2 was observed in 6 patients (12%), thinning of left ventricle (LV) myocardium in 15 patients (29%) and pericardial effusion in 10 patients (19%). LV and right ventricle (RV) ejection fractions were altered in 12 patients (23%) and 11 patients (21%), respectively. LV diastolic dysfunction was found in 15/43 patients (35%). LV kinetic abnormalities were found in 16/52 patients (31%) and myocardial delayed contrast enhancement was detected in 11/52 patients (21%). No perfusion defects at rest were found. Patients with limited SSc had similar MRI abnormalities to patients with diffuse SSc. Seven of 40 patients (17%) without pulmonary arterial hypertension had RV dilatation.

Conclusions:

This study shows that MRI is a reliable and sensitive technique for diagnosing heart involvement in SSc and for analysing its mechanisms, including its inflammatory, microvascular and fibrotic components. Compared with echocardiography, MRI appears to provide additional information by visualising myocardial fibrosis and inflammation. RV dilatation appeared to be non-specific for pulmonary arterial hypertension but could also reflect myocardial involvement related to SSc. Further studies are needed to determine whether cardiac MRI abnormalities have an impact on the prognosis and treatment strategy.

Non-randomized, prospective, multi-centre evaluation of the ABSOLUTE .035 peripheral self-expanding stent system for occluded or stenotic superficial femoral or proximal popliteal arteries (ASSESS Trial): acute and 30-day results

AIM

The aim of the paper was to investigate the performance of the ABSOLUTE .035 Peripheral Self-Expanding Stent System in preventing restenosis of superficial femoral or proximal popliteal arteries. Due to a lack of large controlled trials proving its long-term durability femoropopliteal artery stenting is still a matter of debate. In this paper we report the study design, the acute and short-term results of a prospective European registry on the treatment of TASC B and C femoropopliteal lesions with the use of the ABSOLUTE stent.

METHODS

This prospective, non-randomized, multi-centre study enrolled 122 patients with symptomatic peripheral occlusive disease at 14 sites in Europe. Patients were included with obstructed femoropopliteal arteries. Key inclusion criteria were de novo lesions > or = 4.0 mm and < or = 7.0 mm in diameter, and > or = 40 mm and < or = 200 mm in length. Single target vessel treatment had to be performed with a maximum of three stents.

RESULTS

Mean target lesion length was 108 +/- 44 mm (range 22.2 to 200 mm) and mean reference vessel diameter 4.6 +/- 0.8 mm by quantitative angiography; 71% of the lesions analyzable by quantitative angiography (QA) had total occlusions. A total of 227 stents were implanted, 224 of which were deployed successfully (98.7%). Mean percentage of diameter stenosis was reduced from 90.9 +/- 15.5 % (range 41.3 to 100) to 19.0 +/- 8.4% (range 2.3 to 41.5). Device and procedural success were 83.6% each whereas technical success reached 100%. Sixteen lesions had a > or = 30% residual stenosis post-procedure, 6 of them (37.5%) rated as being calcified. Eleven patients experienced major complications (9.1%) and 6 patients experienced minor complications (5%) within 30 days. Duplex ultrasound based 1-month restenosis rate was 9.3%. Target lesion revascularization (TLR) and target vessel revascularization (TVR) rates were 0.8% and 1.7%, respectively and amputation rate was 0.8%. Mean ankle-brachial index (ABI) at rest and after exercise increased significantly from baseline to 30 days follow-up by 0.63 +/- 0.20 to 0.94 +/- 0.17 and from 0.44 +/- 0.23 to 0.85 +/- 0.21, respectively (P<0.001 each).

CONCLUSION

The treatment of TASC B and C femoro-popliteal lesions with use of the ABSOLUTE stent is safe and feasible. Short-term follow-up documents persistent improvement of hemodynamics. The 6- and 12-month data have to be awaited for further conclusions:

[The best of vascular medicine in 2006]

Peripheral arterial disease (PAD) remains an under-diagnosed affection, and the ankle-brachial index (ABI), a simple diagnostic method, is poorly known and seldom used, and the vascular patient's prescription list is frequently insufficient regarding results obtained in large trials with good methodology. The French ATTEST study underlines the fact that ABI is measured in less than 1 out of 3 patients with PAD. In ATTEST study, less than 10% have the triple therapy validated in PAD : antiplatelet drugs, statins and ACE-inhibitors. The international REACH registry included more than 60 000 patients suffering from atherosclerosis, including 8 000 cases with PAD. This survey evidences that in PAD patients, the annual cardiovascular complication rate is significantly higher than in patients with coronary artery disease (18 vs 13%); again PAD appears systematically under-treated when compared to CAD. These epidemiological surveys highlight the importance of screening of atherosclerotic lesions with the aim of setting an active prevention of CV complications. The new guidelines insist on the screening of PAD in patients at risk, as well as on the importance of the global management after initiating the triple therapy, independent of the CV risk factors. In a 5-year longitudinal study from an initial cohort of 2265 subjects, Aboyans et al. studied the progression of PAD by repeated measurements of ABI at the level of ankles and toes. Factors of progression for large-vessels PAD were active smoking, the total/HDL-cholesterol ratio, Lp(a) and CRP. Importantly, diabetes was not associated to the PAD progression in large vessels, but in contrast, it was the sole factor associated to the progression of PAD in small vessels. In an Austrian study published this year in the NEJM, Schillinger et al. compared balloon angioplasty versus the use of Nitinol stent for the treatment of long stenoses of the superficial femoral artery. In case of claudication, these lesions are usually treated medically, whereas surgery is required for more severe cases. The fact that stenting these long lesions of the superficial femoral artery provides benefits in terms of restenosis opens a approach for the endovascular therapy, to be confirmed by larger trials.

[Usefulness of magnetic resonance angiography in the screening of renal artery stenosis in hypertensive patients: proposition of a diagnostic algorithm: a study of 245 patients]

Usefulness of magnetic resonance angiography in the screening of renal artery stenosis in hypertensive patients: proposition of a diagnostic algorithm: a study on 245 patients. Different non-invasive techniques, including Duplex, spiral angioscan, and magnetic resonance angiography (MRA) are available for the diagnosis of renal artery stenosis (RAS). The aim of this study was to assess the diagnostic performances of MRA and the MRA-Duplex couple in the diagnosis of RAS. Between September 2003 and January 2005, 245 patients benefited from a renal MRA for the assessment of hypertension etiology. The MRA-Duplex couple was performed in 228 patients. Renal arteriography was performed in case of abnormalities observed with MRA and/or Duplex (n=41). The sensitivity and specificity of MRA were respectively at 100% and 23%. The sensitivity was notably higher in the right renal artery (100 vs. 73%). The sensitivity and specificity of Duplex were respectively at 71 and 85%. The concordance between the two exams was disappointing (kappa at 0.39 for the right side and 0.62 for the left side), leading to the interest of the MRA-Duplex association for excluding the presence of RAS (sensitivity and negative predictive value=100%). However, using the MRA-Duplex couple led to a high number of false positive cases, due to MRA, leading to 11 angiograms out of 41 exams, without any significant RAS. In case of suspicion of RAS, the MRA-Duplex couple permits to exclude definitely the diagnosis of RAS. In case of discordance between the 2 exams, it would be useful to require a spiral angioscan and/or redo a Duplex exam using contrast agents, prior to angiography with a therapeutic goal. These management modalities might be useful to avoid the number of normal angiograms, with an inherent risk of complications and cost excess.

[Hypertension revealing aneurysmal renal fibrodysplasia]

A 20-year-old woman consulted for severe hypertension which revealed aneurismal stenosing fibrodysplasia of the renal arteries. The diagnosis was established by duplex Doppler which visualized tight stenosis of the distal portion of the right renal artery and the proximal portion of the left, associated with aneurismal lesions downstream from the strictures (1.8 cm on the right and 1.3 cm on the left). The lesions were highly suggestive of fibrodysplasia and were confirmed by magnetic resonance angiography. Endoluminal revascularization was undertaken because of the severe hypertension and the presence of arterial lesions. Revascularization was unsuccessful and severe hypertension persisted. Surgery was performed in two stages. The first procedure consisted in resection of the left aneurismal lesion with aortorenal internal saphene bypass. Secondarily, exclusion of the right aneurysm was performed with cure of the stricture by extracorporal renal surgery with anastomosis of the renal artery to the aorta and the renal vein to the vena cava. Clinical outcome was favorable. Angioscan and duplex Doppler controls at three and six months confirmed the anatomic success of the revascularization. Aneurysm of the renal artery, like renal artery stenotic dysplasia, is a rare but probably underestimated condition due to insufficient screening. This diagnosis should be entertained in hypertensive young women. There is risk of rupture of the aneurysm. Aneurysmal lesions can be associated with renal artery stenosis which usually involves a short segment of the artery, as in our case. Renal aneurysms should be treated when one of the following elements is present: aneurysm measuring more than 20 mm, progressing aneurysm, dissection, discovery in a patient with a renal risk (single kidney, renal insufficiency), desire for pregnancy, severe hypertension recently discovered in a young subject associated with dysplastic stenosis, isolated aneurysm associated with recent severe hypertension, as reported here.

[The best of vascular medicine in 2005]

It is illusory to think that one year is long enough to establish all the truths that will guide our clinical practice in vascular medicine. On the contrary, one year was long enough to contradict what the preceding twelve months had set out to demonstrate. Consequently, promising trials in the treatment of abdominal aortic aneurysms by endoprostheses have been the object of contradictory debate with regards to the long-term benefits. In fundamental research, circulating progenitors of endothelial cells have been shown to be a marker of atherosclerosis, but is it a better marker than LDL-cholesterol values? The demonstration that these progenitors are of value in the treatment of essential ischaemia of the lower limbs is awaited. Finally, ximelagatran, a direct thrombin antagonist, seemed to have all the qualities of an ideal anticoagulant: easy to use, safe... until the report of raised hepatic enzymes, the clinical relevance of which remains to be determined. In the good news section: the Systolic Pressure Index, an unquestioned marker of arterial disease. Its reduction was known to be correlated with the prevalence of cardiovascular complications. However, it has now been shown that an increase in the index is also associated with cardiovascular complications, a real U-shaped curve. Renal arterial stenosis should be considered in patients with left ventricular failure presenting with flash pulmonary oedema. In the absence of cardiac pathology, BNP would seem to be a good biological marker of haemodynamically significant renal arterial stenosis. Finally, should superficial femoral artery stenosis be treated by an active stent. To date, there is no formal proof.

[Tako-tsubo syndrome and left ventricular obstruction: report of one case]

We report here the case of an 80 year old female suffering from Tako-tsubo syndrome diagnosed following type B aortic dissection, treated surgically with an aortic endoprosthesis. The recovery was marked by the secondary development of left intraventricular obstruction. Regression of the electrical and ultrasound anomalies was slow, taking 4 months of treatment with a beta-blocker. The intraventricular obstruction seemed to occupy a central role in this case, and we discuss the significance of this mechanical phenomenon in the pathophysiology of this syndrome.

Imaging of aortic dissection by helical computed tomography (CT)

Aortic dissection is the most frequent cause of aortic emergency, and its outcome is still frequently fatal. The management of this pathology has changed with the development of endovascular means. Nowadays, imaging modalities are helpful in management decision-making by providing information such as identification of entry tears along the aorta and involvement of the visceral branches of the abdominal aorta. Multi-slice CT scanning now appears to be the modality of choice for complete examination of the entire aorta. We review the parameters of image acquisition and contrast injection; appearances on CT of acute and chronic dissection are illustrated. Diagnostic pitfalls in CT imaging of acute dissection are discussed. Imaging of the post-surgical aorta and of chronic dissection is outlined. Intra-mural hematoma and penetrating aortic ulcer are subtypes of aortic dissection, and their appearances on CT scanning are also presented.

[Clinic and morphologic evolution five years after a renal atherosclerotic artery stenosis (RAS): a study of twenty nine hypertensive patients population]

The indication of renal atherosclerotic artery stenosis revascularisation is always debated in clinical practices when arterial hypertension is stabilized by the treatment, especially if the stenosis is discovered fortuitously. The clinician needs clinical and morphological markers which will indicate or not the revascularisation in the situation of "nephronic protection". The benefits of angioplasty have been studied on the blood pressure, the creatinine clearance, the glomerular function analyzed by scintigraphy, the renal length and more recently on the mean cortical thickness (MCT). The follow-up of these studies is generally inferior to 2 years. In this work, we tried to estimate the clinic and morphologic evolution 5 years after a unilateral artery stenosis angioplasty. From a group of 249 patients who had a renal angioplasty between January 1995 and January 2000 (T0), 29 patients with refractory hypertension and with a unilateral atherosclerotic renal artery stenosis on spiral computed tomographic angiography (TCA) performed at T0 [17 M; 12 W; medium age 68.6 +/- 10 years] were included. The TCA performed at 5 years (T5) eliminated a new renal arterial stenosis or restenosis. We have analyzed 29 revascularized kidneys (kidney S) and 29 controlateral kidneys (kidney C), the blood pressure and renal function. The renal length (mm) was at T0: kidney C=99.4 +/- 13.5; kidney S=93.5 +/- 10.8 and at T5: kidney C=99.4 +/- 12.6; kidney S=94.2 +/- 10.7. MCT (mm) was at T0: kidney C=7 +/- 1.2; kidney S=6.6 +/- 1.1 and at T5: kidney C=6.2 +/- 1.2; kidney S5=6 +/- 1. The cortical atrophy got worse while the renal length and creatinine clearance were stable: only diastolic blood pressure was controlled (78.8 mmHg +/- 11.9). In spite of small strength, this study arguments the fact that the angioplasty isn't sufficient to control the arterial hypertension in an atheromatous context, not allowing to slow the evolution of distal cortical lesions with however a stability of creatinine clearance.

Quand, comment et pourquoi réaliser une exploration des artères rénales ?

The objectives of this course are both: to describe acquisition, injection and reconstruction parameters of volumic images for renal arteries examination and specific signs; to discuss the role of the different images in the diagnosis and in the therapeutic management. Ultrasound is one of the best imaging for the analysis of renal arteries in the detection of stenosis even if the sensitivity is less (around 85%)compared to CT Angiography (95%) and MR Angiography (90%). Because of this advantage and of 3D evaluation, CTA and MRA are sometimes in the first line for renal artery evaluation and can assess morphology before angioplasty. Renal scintigraphy with Captopril test and renin dosage are only used for small kidney evaluation. Arteriogram is systematically followed by angioplasty if possible. With the new endovascular materials, complications decrease (less than 5% with a major reduction in cholesterol emboli) and indications of endoprosthesis increase (71% of stenting with half of it in direct stenting technique). This course will give practical tools for imaging acquisition, specifically 3D imaging, for indications and management of lesion in accordance to symptoms and morphology.

Risk factors of early and late complications in patients undergoing endovascular aneurysm repair

OBJECTIVES

to identify pre-operative factors that could predict complications following from transluminal repair of abdominal aortic aneurysms (AAA).

METHODS

during a 5-year period, 96 consecutive patients underwent elective endovascular treatment of a AAA. In all patients, helical CT and/or Magnetic Resonance Imaging (MRI), and plain abdominal roentgenogram were performed at 1, 3, 6, 12, 18, and 24 months and yearly thereafter. Angiography was performed systematically 1 year after the stent-graft implantation, or earlier if helical CT or MRI diagnosed an increase in the maximal transverse diameter or a high flow endoleak.

RESULTS

early (<30 days) morbidity (12%) was significantly increased by pre-operative renal insufficiency (p < 0.01). Early mortality (2%) correlated with ASA score (p = 0.01). Median follow-up was 27 months (range 3-66). Mortality (12%) during follow-up was correlated to the pre-operative coronary status (p = 0.01). A type I endoleak was diagnosed in 18 patients (19%). Common iliac artery diameter was correlated with the presence of type I endoleak (p < 0.001). A type II endoleak was diagnosed in 47 (49%) patients. The diagnostic of type II endoleak was significantly increased (p = 0.001) in patients with pre-operative patent IMA associated with more than four patent lumbar arteries. The anatomic characteristics of the aneurysm were correlated to the additional endovascular procedures during stentgraft implantation (p = 0.01), and to the implantation of a complementary iliac limb extension during follow-up (p = 0.01).

CONCLUSIONS

the risk factors determined by this statistical analysis could help surgeons to select more accurately patients suitable for endovascular treatment.

Percutaneous endovascular treatment for stenoses and occlusions of infrarenal aorta and aortoiliac bifurcation: midterm results

OBJECTIVE

evaluation and comparison of the endovascular treatment of isolated aortic and aortoiliac atherosclerotic lesions (stenoses and occlusions).

METHODS

a percutaneous endovascular procedure was performed in 52 patients (38 men and 14 women) with a mean age of 52 years (range, 25-85 years). The baseline angiogram showed 35 aortic lesions (31 stenoses, 4 occlusions) and 17 aortoiliac lesions (14 stenoses, 3 occlusions). Percutaneous techniques used in this series included variable combinations of transluminal angioplasty and stenting. All stents placements were performed over-the-wire using the transfemoral route (most often bilateral approach). Clinical examination and Duplex-scan were performed at discharge, 1 month, 6 months, 12 months, and then yearly.

RESULTS

technical success was 100% for aortic and aortoiliac lesions. Angiographic success rates were comparable for aortic (91%) and aortoiliac (94%) lesions. No death occurred during or early after the endovascular intervention. Duplex-scan confirmed 100% patency rate at discharge. There was no significant difference between the aortic (94%) and aortoiliac (96%) groups regarding immediate clinical improvement. Mean follow-up was 34+/-31 months (range, 0-130 months). The cumulative primary patency rate at 36 months was 85% in the aortic group and 86% in the aortoiliac group. Clinical success, defined as a symptom-free status at the end of follow-up, was also similar in both groups.

CONCLUSION

endovascular treatment of isolated aortic lesions of the infra-renal aorta has favorable outcomes comparable to those of aortoiliac lesions.

Stent-graft repair of the thoracic aorta: short-term results

The purpose of this study was to evaluate clinical feasibility and immediate outcome of stent-graft repair of the thoracic aorta. From December 1999 to January 2001, a total of 14 patients underwent stent-graft repair of the thoracic aorta. The underlying etiologies were traumatic rupture of the aortic isthmus in four cases, Stanford type B dissection in four, thoracic aortic aneurysm in three, penetrating atherosclerotic ulcer in two cases, and postoperative aortoesophageal fistula in one case. Stent-graft placement was performed under angiographic control in all cases in association with transesophageal echography in seven cases. The procedure was performed under emergency conditions in five cases. Thirteen patients presented contraindications for surgery. Stent-graft placement was successful in all cases. No further surgery has been performed in any case. Thus we conclude that endovascular treatment of the thoracic aorta using stent grafts is a promising therapeutic modality in patients with contraindications for conventional surgical treatment.

Endovascular treatment of peripheral artery disease with expanded PTFE-covered nitinol stents: interim analysis from a prospective controlled study

PURPOSE

Current covered peripheral stent designs have significant drawbacks in terms of stent delivery characteristics and flexibility. The aim of this study was to analyze the technical performance, safety and initial clinical efficacy of expanded polytetrafluoroethylene (PTFE)-covered nitinol stents for arteriosclerotic peripheral artery disease.

METHODS

Eighty-two patients underwent implantation of PTFE-covered nitinol stents for iliac and/or femoral obstructions. The study was conducted prospectively in seven European centers and one Canadian center. Patients were controlled clinically and by duplex ultrasound follow-up. Data up to discharge were collected in 79 patients. Seventy-four patients have thus far received 1 month follow-up and 32 patients, 6 month follow-up examinations.

RESULTS

The average lesion length measured 47 mm for the common and external iliac arteries and 50 mm for the femoral arteries. The mean severity of the stenoses was reduced from 94% to 4% in the iliac arteries and from 98% to 7% in the femoral arteries after stent placement and dilatation. One device deviation (inadvertent stent misplacement) and one puncture-related severe adverse event with formation of a pseudoaneurysm occurred. There were occlusions of the stent in five patients. No infections were noticed.

CONCLUSION

The interim analysis of this trial using PTFE-covered nitinol stents indicates that a strategy using primary implantation of this stent type is technically feasible, has an acceptable safety profile and is effective from a short-term perspective.

[Important of magnetic resonance angiography with gadolinium injection in pulmonary vein diseases]

The study of the pulmonary veins by echocardiography is sometimes difficult especially when the ultrasonic window is restricted. Conventional angiography is the classic reference examination but it exposes the patient to ionising radiation and requires the injection of an iodine contrast product. Another technique that can provide the essential information is magnetic resonance angiography (MRA) with injection of gadolinium. It was performed in 9 patients for suspected congenital or acquired anomalies of the pulmonary veins between June 1999 and December 2001. The patient's ages varied from 1 month to 10 years. The examinations were carried out on a 1.5 T Vision machine (Siemens, Erlangen, Germany) without "cardiac gating" or apnoea after parental consent. MRA with gadolinium injection showed 5 drainage anomalies (3 partial pulmonary venous refluxes in the superior vena cava, 2 scimitar syndromes) and 3 stenoses (one due to compression by an aneurysm of the left pulmonary artery, a second secondary to pericardial agenesis, and a third secondary to hypoplasia of an isolated vein). MRA allowed three dimensional visualisation of these anomalies. This is a rapid, non-invasive and certain imaging technique which does not expose the patient to ionising radiation. It is therefore of significance in the investigation of anomalies of the pulmonary veins complementing echocardiography, and could in future replace cardiac catheterisation.

Rupture of an aneurysm of the coronary sinus of Valsalva: diagnosis by helical CT angiography

A 75-year-old man presented with a 5-day history of upper chest discomfort. On auscultation, there was a systolic murmur in the left parasternal area that radiated to the apex. Electrocardiography showed flat T waves in the anterior precordial leads. Chest X ray revealed mediastinal enlargement. Transthoracic echocardiography showed a dilated proximal ascending aorta with moderate aortic regurgitation. A contrast-enhanced helical CT scan, performed to eliminate an aortic dissection, showed a ruptured left coronary sinus of Valsalva aneurysm, confirmed at surgery. This case highlights the fact that helical CT, in patients with suspected aortic dissection, may reveal other pathology that accounts for the clinical presentation.

Embolization of type II endoleaks after aortic stent-graft implantation: technique and immediate results

PURPOSE

We report the procedural details and immediate results of treatment of type II endoleaks after aortic stent-graft implantation.

METHODS

In a consecutive series of patients who had either Vangard (n = 53) or Talent (n = 7) aortic stent-grafts implanted, type II endoleaks were confirmed by means of angiography in 18 patients, with a mean (+/- SD) age of 69 +/- 11 years; 16 patients had Vangard stent-grafts, and two patients had Talent stent-grafts. After superselective catheterization of the feeding vessel, with 3F microcatheters, and liberal injections of vasodilators, embolization was performed with either a mixture of biologic glue and Lipiodol (n = 16) or Microcoils (n = 2).

RESULTS

The procedure was performed through the femoral artery in 16 patients and through the brachial artery in the remaining two patients. Overall, superselective catheterization and embolization were successfully undertaken in 17 (94.4%) of 18 patients. In the remaining patient, superselective catheterization proved impossible. This patient was treated with an injection of microparticles completed by means of embolization of biologic glue more proximally in an iliolumbar branch. During follow-up (mean, 13.3 months) after embolization, the aneurysm sac shrank in 13 (72.2%) of 18 patients. A new type II endoleak was diagnosed on helical computed tomography or magnetic resonance imaging in two (11.1%) of 18 patients.

CONCLUSION

Percutaneous embolization is a safe and effective technique for treatment of type II endoleaks. However, despite these initially promising results, large long-term follow-up studies will be required to confirm its efficiency.

[Recurrent edema of the face and neck in a chronically hemodialyzed patient]

We report the case of a patient undergoing long-term hemodialysis admitted to hospital for diagnosis of recurrent face and neck edema influenced by dialysis sessions with paroxysmal dyspnea. We considered the possible role of allergy to ethylene oxide and to formaldehyde without diagnostic confirmation. Dialyzer complement activation was suspected but changing the dialyzer did not improve the symptoms. Anti-histaminic and corticosteroid therapy did not modify symptoms. A mild hemithoracic collateral circulation occurred and led to the discovery of a superior vena cava syndrome. Computed tomography and bilateral upper limb contrast venography visualized a thrombus in the superior vena cava extending into the right venous brachiocephalic arm from the central vein catheter. A stent was inserted into the superior vena cava which, together with anticoagulant therapy, led to rapid resolution of the symptoms. Superior vena cava syndrome related to a central catheter and hypersensitivity reactions should always be considered as possible causes of recurrent face and neck edema in patients on long-term hemodialysis.

[Are demographic characteristics of hypertensive patients different with renal artery stenosis?]

Atheromatous renal disease is more and more involved in end stage renal failure in polyatheromatous patients. The goal of this work was to study the demographic differences between hypertensive patients with renal artery stenosis (RAS) or without RAS.

METHOD

Between November 1995 and July 1997, 49 hypertensive patients were included consecutively for a suspicion of RAS. Age, sex, hypertension history, tabagism, cardiovascular heredity, body mass index, diabetes history, hypercholesterolemia, kalmia, serum creatinine, creatinine clearance, systolic blood pressure (SBP), diastolic blood pressure (DBP) and pulse pressure (PP) were studied. A renal echo-doppler and a renal TDM were performed in all patients. A renal arteriography was performed in 23 patients with a RAS suspicion after the two morphologic exams. The demographic characteristics of both clinical groups control (group 1) and patients with unilateral RAS (group 2), were compared.

STATISTICS

Descriptive analysis, Wilcoxon test, Khi 2 test, spearman correlation (p < 0.05).

RESULTS

Group 2 patients were significantly older than group 1 patients (p = 0.008) with a mean age difference of 8 years. Creatinine clearance was lower in patients suffering from RAS with a mean difference of 23 mL/min between groups 1 and 2 (p = 0.0007) but we also had to take into account the negative correlation existing between creatinine clearance and age (r = 0.63; p = 0.0001) when interpreting these results. The DBP was lower (p = 0.03) and the PP higher (p = 0.01) in group 2. The SBP was higher in group 2 but this result was not significant. Mean differences in SBP and PP between group 1 and group 2 were 6 mmHg and 15 mm Hg respectively. Smoking was more common in group 2 (p = 0.04). The history of hypertension, cardiovascular heredity, sex ratio (M/F), body mass index and prevalence of diabetic were comparable between the two clinical groups.

CONCLUSION

Although there were demographic differences between the two clinical groups, no clinical or biological variable could be used alone to identify which patients suffered from renal stenosis, because the distribution of these variables did not differ significantly between the two groups and the effective was small. Then, we thought that Krijnen's predictive rule is interesting in the screening of hypertensive patients with RAS suspicion.

[Method of studying renal morphology in hypertensive patients with and without renal artery stenosis]

Although the size of the kidney is still the most commonly used as morphological parameter, it is not enough sensitive for early detection of ischemic nephropathy.

PURPOSE

To study a novel method of renal morphology analysis using spiral computed tomography angiography (CTA) in hypertensive patients with or without unilateral atheromatous renal artery stenosis (RAS).

METHODS

Forty-nine hypertensive patients suspected RAS underwent spiral CTA. Arteriography showed significant RAS in 26 patients. Renal length, 3 upper and 3 lower cortical thicknesses were measured in 46 control kidneys (C) i.e. 23 patients without RAS (group 1), in 26 stenosed (S) and in 26 opposite kidneys (OPP) i.e. 26 patients with unilateral RAS (group 2). Mean cortical thickness (MCT), cortical area (CA), medullary length (ML) were calculated in the same groups. The reproducibility and agreement of measurements were investigated in two groups. The demographic parameters (age, sex, bodymass index, and history of hypertension) were correlated with morphological parameters in group 1.

RESULTS

The reproducibility and agreement of measurements were confirmed (R2 = 0.53 to 0.93) except for anterosuperior thickness. The C kidneys were of comparable morphology: MCT (mm) = 9.1 +/- 0.6; 9.2 +/- 1.0, CA (mm2) = 950 +/- 119; 934 +/- 157, ML (mm) = 85 +/- 11. In group of Opp kidneys, MCT = 7.9 +/- 1.4 mm, CA = 806 +/- 210 mm2, ML = 84 +/- 13 mm. In group of S kidneys, MCT = 6.6 +/- 1.6 mm, CA = 612 +/- 193 mm2, ML = 77 +/- 14 mm. Demographic parameters were not correlated to renal morphology.

CONCLUSION

Spiral CTA is a suitable method to study renal morphology. Cortical thickness and medullary length could be used to obtain a reliable diagnosis of early ischemic nephropathy.

Prospective evaluation of magnetic resonance imaging after endovascular treatment of infrarenal aortic aneurysms

OBJECTIVES

to evaluate the sensitivity and specificity of magnetic resonance imaging (MRI) in the detection of type II endoleaks during follow-up after endovascular treatment of intra-renal aortic aneurysms.

DESIGN

prospective study.

MATERIAL AND METHODS

between March 1996 and November 1999, 31 patients with infra-renal aortic aneurysms who underwent stentgraft implantation were followed with helical CT and MRI, including magnetic resonance angiography (MRA), at 1 and 6 months after the procedure. Arteriography was performed between 6 and 12 months after intervention. The parameters studied included the change in the maximum anteroposterior and transverse diameters, the nature of the signal on T1 and T2 weighted sequences (homogeneous vs heterogeneous), the presence or absence of Gadolinium uptake on MRI or of contrast uptake on helical CT (early and late phases) in the sac of the aneurysm. On MRA, stentgraft patency and endoleak detection were studied.

RESULTS

arteriography demonstrated an endoleak in 19 patients (18 type II, and 1 type I endoleak). MRI at 6 months detected 18/19 endoleaks on T1 weighted sequences after injection of Gadoliniumj; there were 2 false positives. MRA sequences confirmed stentgraft patency in all patients, but did not diagnose type II endoleaks. Helical CT (late phase) at 6 months detected 10/19 endoleaks; there was 1 false positive. The sensitivity of MRI after injection of Gadolinium and of helical CT for the detection of type II endoleaks were 94% and 50% (p=0.003) respectively. The mean maximal anteroposterior and transverse diameters were similar on MRI and on helical CT at 1 month and at 6 months.

CONCLUSION

MRI after injection of Gadolinium is more sensitive than helical CT in the detection of type II endoleaks after stentgraft implantation. Its more widespread use may permit earlier intervention in such patients.

[Endovascular therapy of renal artery stenosis: technical results with the Palmaz-Corinthian stent]

OBJECTIVE

To evaluate the technical performance and delivery characteristics of the Palmaz-Corinthian stent for endovascular therapy of atherosclerotic renovascular disease.

METHODS

61 patients underwent implantation of 76 Palmaz-Corinthian (PC) stents in 72 arteries. 50 original PC and 26 PC stents with the modified IQ-design were employed. The indications comprised primary stenting of ostial (n = 49) or truncal (n = 1) stenosis or occlusion (n = 3), and selective stenting following complicated (dissection, n = 4) or unsuccessful (n = 8) angioplasty. The remaining stents were placed in patients with recurrent stenosis (n = 5) or acute aortic dissection (n = 2) involving the renal artery. Mean severity and length of stenosis were 81.3% and 9.8 mm, respectively. 39 lesions were rated eccentric or calcified. Data on technical success, complication rate, delivery characteristics and ease of placement compared to standard renal stents were retrieved from a prospective multicenter registry.

RESULTS

Stent delivery was successful in all patients, major complications were not reported. Stent placement was suboptimal in 7 of 72 cases: 4 stents were located too distally in the renal artery, necessitating proximal coaxial overstenting in 2 cases. The distal part of the stenosis was incompletely covered and the orifice of a segmental branch inappropriately overstented in one case each. One stent was dislodged from the balloon, resulting in stent protrusion in the aortic lumen. Significant residual stenosis after stenting was not observed. Overall stent deliverability, trackability and potential repositioning inside the stenosis were rated positive, radio-opacity was rated superior for the IQ design.

CONCLUSION

Technical performance and delivery characteristics of the Palmaz-Corinthian stent have been significantly improved compared to the Palmaz design, allowing mostly correct placement in renal artery stenoses with a low complication rate.

Rare variations in renal anatomy and blood supply: CT appearances and embryological background. A pictorial essay

Helical CT angiography is increasingly used for the evaluation of the kidneys and the renal vessels. Knowledge of the potential variants in renal and renal vascular anatomy and of their appearances on helical CT are thus indispensable for radiologists who perform and interpret such examinations. We report six cases of anatomic variants that we encountered in our tertiary referral centre over the past 5 years, during which time we have performed 4850 helical CT angiograms, including 1432 renal artery examinations. These represent rarer anomalies in renal vascularization, most of which were associated with renal malformations (horseshoe kidney with or without cortical torsion, renal malrotation, single kidney, and thoracic origin of a renal artery). We present the helical CT findings and discuss the possible embryological mechanisms and the practical implications of these abnormalities for the radiologist.

Diagnosis and treatment of type II endoleak after stent placement for exclusion of an abdominal aortic aneurysm

After endovascular treatment of AAA, regular clinical and radiologic surveillance is necessary for early diagnosis and treatment of mid-term and long-term complications. The purpose of this report was to evaluate the efficacy of magnetic resonance imaging (MRI) in screening for type II endoleaks and assessing the results of treatment by embolization. From March 1996 to November 1999, 64 patients with uncomplicated infrarenal abdominal aortic aneurysm (AAA) were treated by endovascular exclusion with a covered aortic stent. Radiological surveillance included plain abdominal roentgenogram (PAR), CT scan, and pelvioabdominal MRI at 1 month, 3 months, 6 months, and every 6 months thereafter. Arteriography was performed routinely after 1 year or sooner if an endoleak was suspected. Based on the results of this study, MRI seems to be more sensitive than CT scanning for detection of type II endoleaks. The negative predictive value of MRI is also better. In this series, all endoleaks were treated by embolization. In most cases, the maximum transverse diameter and maximum anteroposterior diameter decreased after embolization. Further follow-up will be necessary to confirm these findings.

Mechanical thrombectomy in patients with deep venous thrombosis

PURPOSE

To report our experience with mechanical thrombectomy in proximal deep vein thrombosis (DVT).

METHODS

Eighteen patients with a mean (+/- SD) age of 37.6 +/- 16.1 years who presented with DVT in the iliac and femoral vein (n = 3), inferior vena cava (n = 5), or inferior vena cava and iliac vein (n = 10), were treated with the Amplatz Thrombectomy Device after insertion of a temporary caval filter.

RESULTS

Successful recanalization was achieved in 15 of 18 patients (83%). Overall, the percentage of thrombus removed was 66 +/- 29%: 73 +/- 30% at caval level and 55 +/- 36% at iliofemoral level. Complementary interventions (seven patients) were balloon angioplasty (n = 2), angioplasty and stenting (n = 2), thrombo-aspiration alone (n = 1), thrombo-aspiration, balloon angioplasty, and permanent filter (n = 1), and permanent filter alone (n = 1). There was one in-hospital death. Follow-up was obtained at a mean of 29.6 months; three patients had died (two cancers, one myocardial infarction); 10 had no or minimal sequelae; one had post-phlebitic limb.

CONCLUSION

Mechanical thrombectomy is a potential therapeutic option in patients presenting with proximal DVT.

[Intravascular Doppler for the evaluation of renal blood flow: validation and demonstration of vessel reactivity]

AIM

To assess the feasibility and to demonstrate the potential clinical application of intravascular doppler in the evaluation of renal blood flow in patients with hypertension and normal renal arteries.

MATERIALS AND METHODS

Intravascular doppler was used to measure renal blood flow in 19 patients (34 kidneys) during arteriography to rule out renovascular hypertension. Arteriography showed no evidence of renal artery stenosis in any patient. Hemodynamic parameters, renal artery diameter, and doppler measurements were undertaken at baseline, after injection of a bolus (10 ml) of normal (0.9%) saline, and after injection of isosorbide dinitrate (1 mg diluted in 10 ml normal saline).

RESULTS

Repeated measurements of renal blood flow confirmed the reproducibility of the technique. Basal blood flow was similar in both right and left kidneys; injection of vehicle solution (10 ml normal saline) had no effect on doppler parameters. Injection of isosorbide dinitrate resulted in a significant increase in renal blood flow velocity reflecting an increase in renal blood flow; this demonstrates the existence of a renal flow reserve. The degree of increase in renal blood flow varied significantly between kidneys.

CONCLUSIONS

Intravascular doppler is a safe, effective, and reproducible technique for measurement of renal blood flow. It allows evaluation of variations in renal blood flow in response to diverse vasoactive drugs or other vasomotor stimuli. The present study demonstrated the heterogenous response of renal blood flow in response to vasodilator stimuli.

MR-guided balloon angioplasty of stenosed aorta: in vivo evaluation using near-standard instruments and a passive tracking technique

The purpose of this study was to assess the feasibility of magnetic resonance (MR)-guided balloon angioplasty of a stenosed aorta on an open low-field magnet using a passive tracking technique. Visualization of vessels and position of instruments were realized by using a fast low-angle shot (FLASH) sequence. Catheters and guidewire were prepared for susceptibility-based MR visualization. Standard balloon catheters were inflated with diluted gadolinium, and nitinol guidewires were modified by incorporation of iron oxide markers into their walls. After validation on a flow phantom, balloon angioplasty was performed on an in vivo model of arterial stenosis. Creation of abdominal aorta stenosis was realized in five piglets. MR-guided balloon angioplasty of the aorta was performed with success in all but one. In one of them, stent implantation was achieved in the descending aorta. Balloon angioplasty using a passive tracking technique is a simple concept that can be realized with near-standard instruments and any MR imaging system. This represents an advance toward MR-guided vascular interventions in the future.

Doppler flow wire evaluation of renal blood flow reserve in hypertensive patients with normal renal arteries

PURPOSE

To study the vasomotor responses of the renal microcirculation in patients with essential hypertension.

METHODS

We studied the reactivity of the renal microcirculation to papaverine, with intraarterial Doppler and quantitative arteriography, in 34 renal arteries of 19 hypertensive patients without significant renal artery stenosis. Isosorbide dinitrate was given to maximally dilate proximal renal arteries. APV (average peak blood flow velocity) was used as an index of renal blood flow.

RESULTS

Kidneys could be divided into two distinct subgroups based on their response to papaverine. An increase in APV of up to 55% occurred in 21 kidneys, an increase > 55% in 13 kidneys. Within each group the values were normally distributed. Both baseline APV and the effect of papaverine on mean velocity differed significantly between groups.

CONCLUSION

There seems to be a subgroup of patients with essential hypertension that has an impaired reactivity to papaverine, consistent with a functional impairment of the renal microcirculation. Further studies are required to determine whether this abnormality contributes to or results from elevated blood pressure.

Endovascular treatment for dissection of the descending aorta

Surgery for acute ischaemia complicating dissection of the descending aorta is associated with high mortality. We used an endovascular fenestration approach (scissor technique) to treat seven of 12 patients with ischaemic complications of descending aortic dissection; the remaining five patients were treated by stent implantation. Four of the 12 patients died (two in the fenestration group and two in the stenting group) in the days after the procedure. The remaining eight were symptom-free a mean of 9.4 (SD 8) months later. We suggest that the fenestration approach is a promising addition to endovascular treatment for patients with ischaemic complications of descending aortic dissection.

[Giant multifocal venous malformation with monomelic predominance]

INTRODUCTION

Venous malformations are usually easy to recognise. We describe one case in which the clinical aspect was suggestive of Maffucci's syndrome.

OBSERVATION

A 44-year-old male, had numerous angiomatous nodules which could be emptied by pressure since infancy. The progressive increase in volume of these lesions on the arms and forearms led to enormous deformation and major disability. The thoracic area and the right foot were also affected to a lesser degree. Two endobuccal lesions were also found on the clinical examination The cutaneous lesions were tender and occasionally hyperhidrosis was present. The presence of phleboliths on Xray and the presence of venous and capillary cavities with numerous thrombi confirmed the diagnosis of venous malformation. Following the failure of the Ethibloc(R) embolization, eight excisions were made in a two-year-period with a good functional result. Elastic strapping was then applied.

DISCUSSION

The diagnosis of venous malformation was based on clinical, radiological and histological findings. The absence of chondroma excluded the diagnosis of Maffucci's syndrome. Spindle cell hemangioendothelioma, "blue rubber bleb nevus" and glomangiomatosis were confirmed by the histological findings. The absence of port-wine stain or bone hypertrophy and the presence of multiple nodules excluded Klippel-Trenaunay syndrome. The presence of multifocal involvement with oral lesions, the severity of the deformation and the relative success of the surgical procedure make this case unusual.

Anatomic variation in the origin of the main renal arteries: spiral CTA evaluation

The aim of this study was to provide quantitative data on the origin and trajectory of the main renal arteries using spiral CT angiography and arteriography. Normal renal artery anatomy was assessed on spiral CT angiography (axial transverse sections and shaded-surface-display reconstructions) in 100 patients referred for renal arteriography who had no significant renal artery stenosis. Two hundred major renal arteries were studied. The vast majority of right (88 %) and left (87 %) renal arteries originated between the lower third of the first lumbar vertebra and the lower border of the second lumbar vertebra. In 50 patients both ostia were at the same level; in the remaining 50 patients, the right ostium was located above the left in 37 patients. On the right, the angle of origin varied from -10 to + 55 degrees (mean + 24 degrees ). On the left, the angle of origin varied from + 30 to -55 degrees (mean -11 degrees ). Spiral CT angiography provides additional anatomic data, notably regarding the angle of origin of the renal arteries, that is potentially useful for planning interventional procedures.