Impact of ultra-low dose CT acquisition on semi-automated RECIST tool in the evaluation of malignant focal liver lesions.

PURPOSE: To compare the evaluation of malignant focal liver lesions (FLLs) using a semi-automated RECIST tool with a standard and an ultra-low dose (ULD) computed tomography (CT) protocol. MATERIALS AND METHODS: Thirty-four patients with malignant FLLs underwent two abdominal-pelvic CT examinations one using a standard protocol and one using an ULD protocol. There were 23 men and 11 women with a mean age 64.3±14.4 (SD) years (range: 22-91 years). Dosimetric indicators were recorded, and effective dose was calculated for both examinations. Mean malignant FLL attenuation, image noise and contrast-to-noise-ratio (CNR) were compared. The largest malignant FLL per patient was evaluated using the semi-automated RECIST tool to determine longest axis length, longest orthogonal axis length, volume and World Health Organisation area. RESULTS: Dosimetric values were significantly reduced by -56% with ULD compared to standard protocol. No differences in mean malignant FLL attenuation values were found between the two protocols. Image noise was significantly increased for all locations (P<0.05) with ULD compared to standard protocol, and CNR was significantly reduced (P<0.05). On the 34 malignant FLLs analyzed, six semi-automated shapes non-concordant with radiologist's visual impression were highlighted with the software, including one FLL (1/34; 3%) with standard CT acquisition only, three FLLs (3/34; 9%) with ULD CT acquisition only and two FLLs (2/34; 6%) with both CT acquisitions. After manual editing, the concordance of the values of the studied criteria between both acquisitions was good and no significant difference was reported. CONCLUSION: Semi-automated RECIST tool demonstrates good performances using ULD CT protocol. It could be used in routine clinical practice with a ULD protocol for follow-up studies in patients with known malignant FLL.

Diagnostic performance of a low dose triple rule-out CT angiography using SAFIRE in emergency department.

OBJECTIVES: To compare the diagnostic performance of "triple rule out" CT angiography (TRO-CTA) at 100kVp using sinogram affirmed iterative reconstruction (SAFIRE) with TRO-CTA at 120kVp using filtered back projection (FBP) in patients with acute chest pain. METHODS: Consecutive non-prepared patients from a single radiological emergency department, referred for acute chest pain evaluation with TRO-CTA, were randomly assigned to two different TRO-CTA protocols. Fifty patients (66% men; mean age, 66.6±19.0 [SD] years [range: 24-97years]) had TRO-CTA at 120kVp with FBP and 97 patients (67% men; mean age, 62.8±17.9 [SD] years [range: 24-93years]) had TRO-CTA at 100kVp with SAFIRE. Two radiologists reviewed the TRO-CTA images for pathologic findings and degree of diagnostic confidence. Image noise, vessel attenuation value, signal-to-noise and contrast-to-noise ratios in five main thoracic arteries were measured for objective and subjective analysis. RESULTS: A total of 147 patients (98 men, 49 women; mean age, 64.7±18.4 [SD] [range, 24-97years) were included with good diagnostic confidence and equivalent pathological findings between the two TRO-CTA protocols. Objective and subjective analysis were identical between protocols and radiologists, except for vessel attenuation in the ascending aorta (P=0.02) and image noise in the pulmonary trunk (P=0.04). The effective radiation dose decreased significantly by 34% in the low dose TRO-CTA using SAFIRE protocol (5.7±2.7 vs 8.6±6.1mSv; P=4.7×10-6). CONCLUSIONS: Low dose TRO-CTA protocol using SAFIRE allows a high confidence diagnostic level with the benefit of a 34% radiation dose decrease compared with a standard TRO-CTA protocol using FBP.

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.

Dose reduction with iterative reconstruction in multi-detector CT: What is the impact on deformation of circular structures in phantom study?

OBJECTIVES: To evaluate the distortion of circular structures induced by the increased image noise related to dose reduction and to assess the effect of iterative reconstruction (IR). METHODS: MDCT acquisitions were performed with 120 kVp for 200/100/60/40/20mAs with 100%/50%/30%/20%/10% of dose. Raw data were reconstructed by filtered back projection (FBP) and with two IR strengths. Image quality indices referred to water and acrylic were measured on a quality image phantom. Areas, perimeters, circularity were measured on the circular inserts of 4.8, 7.9 and 11.1mm on a morphological phantom. RESULTS: Dose reduction resulted in increased image noise and in decreased signal to noise ratio and contrast to noise ratio. IR improved these indices for the same dose without affecting the signal (number CT) and spatial resolution (modulation transfer function). The values of area, perimeter and circularity were altered compared to the actual value and the inserts were visually deformed with the dose reduction. IR improved these three parameters. Image quality indices, areas, perimeters and circularity of inserts were similar between the acquisition at 100% of the dose in FBP, 50% in strength-3 and 30% in strength-5 with different curves of noise power spectrum. CONCLUSION: IR associated to 70% of dose reduction modifies the images smooth (NPS) but maintains adequate image quality indices without causing distortions of circular structures.

Which dose for what image? Iterative reconstruction for CT scan.

PURPOSE: To evaluate the potential of iterative reconstruction for reducing the dose given to the patient during abdominal CT scanning. MATERIALS AND METHODS: A double abdominal CT scan acquisition (Somatom Definition AS+ Siemens) performed without contrast administration at -30% and at -70% of the doses (mAs) was compared to the standard acquisition in 10 patients. The raw data were reconstructed by filtered back projection (FBP) and using the SAFIRE iterative reconstruction method (five levels of iteration). The signal, noise, signal-to-noise ratio (SNR) and the contrast-to-noise ratio (CNR) were compared for three regions of interest, including the kidney, psoas and abdominal fat. RESULTS: The signal in each region of interest was not modified based on the type of reconstruction. The noise level decreased significantly during the passage from the FBP to SAFIRE, as well as with the increase in the SAFIRE level. The SNR and CNR therefore increased with the use of iterative reconstructions. The increase in noise observed between the acquisition at -30% and that at -70% was compensated by the use of higher SAFIRE levels. CONCLUSION: Iterative reconstructions can be used to improve the SNR and CNR at a constant dose or to reduce the dose by keeping the same SNR and CNR on abdominal CT images.

Aortic dissection and malperfusion syndrome: a when, what and how-to guide.

Malperfusion syndrome is a complication of aortic dissection caused by branch-vessel involvement and resulting in end-organ ischaemic dysfunction. Clinical diagnosis is mandatory, and imaging plays a critical role in confirmation and treatment planning. Radiologists must focus on detecting complications (findings of aortic dilation, rupture, organ ischaemia, etc.) and defining vascular compromise and associated malperfusion mechanisms. All these factors guide the multidisciplinary discussion concerning patient management and the suitability of endovascular treatment. Application of dedicated imaging protocols is mandatory in order to answer clinical and anatomical questions. Endovascular therapy has taken a predominant role in the therapeutic management of malperfusion syndrome with aortic fenestration, peripheral stenting and stent-grafting, all of which are procedures within the domain of expertise of current interventional radiologists. The purpose of this editorial is to present a when, what and how-to guide for all radiologists who encounter complicated aortic dissection.

Applications of phase-contrast velocimetry sequences in cardiovascular imaging.

AIMS: To describe and illustrate the main applications of phase-contrast flow quantification in cardiovascular imaging. CONCLUSION: Phase-contrast velocimetry sequences provide an accurate, reliable, reproducible and non-invasive study of blood flow, information which is sometimes not available from other investigation methods. The haemodynamic information obtained from these complement MRI angiography images. They appear to have a range of clinical applications, firstly improving pathophysiological understanding but also contributing to the treatment and follow-up strategy after surgical or endovascular treatment.

[MR imaging of coronary arteries: noncontrast free-breathing whole heart acquisition with ultrafast 3D balanced gradient-echo technique]. / Imagerie par résonance magnétique des artères coronaires: acquisition "coeur entier", en respiration libre, sans injection d'agent de contraste et utilisant la séquence 3D en écho de gradient balancé ultrarapide.

The 3D balanced gradient-echo technique is described along with th eimaging protocol for MR imaging of th ecoronary arteries. A 3D volume with spatial resolution of 0.6 x 0.6 x 0.75 mm composed of 140 slices covering the whole heart is acquired over 10 minutes. The main advantage of this whole heart technique is the possibility to image the coronary arteries along their entire course in a single acquisition. Selection of the navigator positions, timing of image acquisition and its duration through the R-R interval are the main factors requiring optimization.

[Ankle brachial index measurement at the first visit for hypertension: a safe and very useful tool for aortic coarctation screening. A case report]. / L'index de pression systolique dans un premier bilan d'hypertension: outil diagnostique de choix de la coarctation aortique. Un cas rapporté.

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.

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.

[Hypertension revealing aneurysmal renal fibrodysplasia]. / Hypertension artérielle révélatrice d'une fibrodysplasie rénale anévrismale.

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.

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.