Gadolinium-enhanced Magnetic Resonance Angiography Research Articles

The use of ferumoxytol for high-resolution vascular imaging and troubleshooting for abdominal allografts.

Ferumoxytol is an ultrasmall superparamagnetic iron oxide which has been used as an off-label intravenous contrast agent for MRI. Unlike gadolinium-based contrast agents, ferumoxytol remains in the intravascular space with a long half-life of 14-21h. During the first several hours, it acts as a blood-pool agent and has minimal parenchymal enhancement. Studies have shown adequate intravascular signal for up to 72h after initial contrast bolus. Ferumoxytol has been shown to be safe, even in patients with renal failure. Ferumoxytol has shown promise in a variety of clinical settings. The exquisite resolution enabled by the long intravascular times and lack of background parenchymal enhancement is of particular interest in the vascular imaging of solid organ allografts. Ferumoxytol magnetic resonance angiography (MRA) may identify clinically actionable findings months before ultrasound, CT angiography, or Gadolinium-enhanced MRA. Ferumoxytol MRA is of particular benefit as a troubleshooting tool in the setting of equivocal ultrasound and CT imaging. In the following review, we highlight the use of ferumoxytol for high-resolution MR vascular imaging for abdominal solid organ allografts, with representative cases.

Minimizing table time in patients with claustrophobia using focused ferumoxytol-enhanced MR angiography (f-FEMRA): a feasibility study.

To assess the feasibility of a rapid, focused ferumoxytol-enhanced MR angiography (f-FEMRA) protocol in patients with claustrophobia. In this retrospective study, 13 patients with claustrophobia expressed reluctance to undergo conventional MR angiography, but agreed to a trial of up to 10 min in the scanner bore and underwent f-FEMRA. Thirteen matched control patients who underwent gadolinium-enhanced MR angiography (GEMRA) were identified for comparison of diagnostic image quality. For f-FEMRA, the time from localizer image acquisition to completion of the angiographic acquisition was measured. Two radiologists independently scored images on both f-FEMRA and GEMRA for arterial and venous image quality, motion artefact and diagnostic confidence using a 5-point scale, five being best. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) in the aorta and IVC were measured. The Wilcoxon rank-sum test, one-way ANOVA with Tukey correction and two-tailed t tests were utilized for statistical analyses. All scans were diagnostic and assessed with high confidence (scores ≥ 4). Average scan time for f-FEMRA was 6.27 min (range 3.56 to 10.12 min), with no significant difference between f-FEMRA and GEMRA in diagnostic confidence (4.86 ± 0.24 vs 4.69 ± 0.25, p = 0.13), arterial image quality (4.62 ± 0.57 vs 4.65 ± 0.49, p = 0.78) and motion artefact score (4.58 ± 0.49 vs 4.58 ± 0.28, p > 0.99). f-FEMRA scored significantly better for venous image quality than GEMRA (4.62 ± 0.42 vs 4.19 ± 0.56, p = 0.04). CNR in the IVC was significantly higher for steady-state f-FEMRA than GEMRA regardless of the enhancement phase (p < 0.05). Comprehensive vascular MR imaging of the thorax, abdomen and pelvis can be completed in as little as 5 min within the magnet bore using f-FEMRA, facilitating acceptance by patients with claustrophobia and streamlining workflow. A focused approach to vascular imaging with ferumoxytol can be performed in patients with claustrophobia, limiting time in the magnet bore to 10 min or less, while acquiring fully diagnostic images of the thorax, abdomen and pelvis.

Ferumoxytol-enhanced magnetic resonance angiography provides comparable vascular conspicuity to CT angiography in dogs with intrahepatic portosystemic shunts.

Computed tomography angiography (CTA) is currently the gold standard imaging modality for anatomically characterizing canine hepatic vascular anomalies; with conventional, gadolinium-enhanced MR angiography being less frequently utilized. However, both imaging modalities are limited by a brief, first pass peak of contrast medium in the vasculature that necessitates precisely timed image acquisition. A long-acting purely intravascular magnetic resonance imaging (MRI) contrast agent, ferumoxytol, offers the potential to reduce complexity of magnetic resonance angiography (MRA) protocol planning by ensuring diagnostic contrast medium concentration in all the vessels that are targeted for imaging. Aims of this prospective, pilot, methods comparison study were to develop an optimized MRA protocol using ferumoxytol in dogs with hepatic vascular anomalies, perform a dose escalation trial to compare image quality with four-dose regimens of ferumoxytol, and compare accuracy of vascular anatomic depiction based on the gold standard of CTA. Six dogs (10.7-36.1kg) with portosystemic shunts (four intrahepatic left divisional shunts and two intrahepatic right divisional shunts) were recruited for inclusion in the study. A dose-escalation trial was performed to compare image quality at four incremental dose levels of ferumoxytol (1, 2, 3, and 4mg/kg) and to compare the accuracy of vascular anatomic detection to CTA. Ferumoxytol contrast-enhanced MRA (CE-MRA) at 4mg/kg provided similar conspicuity of normal and abnormal vasculature compared to CTA with a minimal decrease in spatial resolution. Findings indicated that ferumoxytol holds promise for comprehensive, single breath hold CE-MRA of all abdominal vessels in dogs with portosystemic shunts. Background information provided in this study can be used to support development of other future applications such as intracranial and cardiac MRA, real-time imaging, flow quantification, and potentially sedated MRI imaging.

Gadolinium-enhanced magnetic resonance versus computed tomography angiography for renal artery stenosis: A systematic review and meta-analysis

Gadolinium-enhanced magnetic resonance angiography (MRA) and computed tomography angiography (CTA) are commonly used for diagnosing renal arterial stenosis (RAS); however, the diagnostic value is yet controversial. The aim of the study was to evaluate the diagnostic values of both methods. Electronic databases, including PubMed, Embase, and the Cochrane Library, were searched for studies, since inception until October 2017. A total of four articles involving 486 subjects were included in the analysis. The summary of sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and area under the receiver operating characteristic (ROC) (AUC) were 0.70, 0.82, 14.54, 0.29, 63.80, and 0.81 for MRA-based diagnosis of RAS, respectively. The pooled sensitivity, specificity, PLR, NLR, DOR, and AUC for CTA detecting RAS were 0.73, 0.96, 13.04, 0.29, 71.99, and 0.93, respectively. Gadolinium-enhanced MRA and CTA provide a satisfactory diagnostic accuracy, thereby playing a critical role in the diagnosis of RAS.

Game changers in vascular and endovascular surgery

Game changers in vascular and endovascular surgery

Diagnosis and management of systemic hypertension due to renovascular and aortic stenosis in patients with Williams-Beuren syndrome.

To describe the incidence, diagnosis, and management of systemic arterial hypertension related to renal artery stenosis in patients with Williams-Beuren syndrome. Sixty-five patients with Williams-Beuren syndrome were evaluated for hypertension. Enrolled patients underwent Doppler sonography of the renal arteries and Doppler echocardiography. Those with Doppler sonography-detected lesions or with normal Doppler sonography but severe hypertension underwent computed tomography or gadolinium-enhanced magnetic resonance angiography of the aorta and renal vessels. Patients needing vascular therapeutic intervention underwent conventional angiography. Systemic arterial hypertension was diagnosed in 21/65 patients with Williams-Beuren syndrome (32%; 13 male) with a mean age of 13.9 years (5mo-20yrs). In 8/21 patients renovascular hypertension was detected. Angioplasty was unsuccessful in five patients with renal artery stenosis, requiring additional treatment. Doppler echocardiography showed cardiac abnormalities in 16/21 (76%) hypertensive patients. Cardiac abnormalities and hypertension in patients with Williams-Beuren syndrome are common. Thus, thorough evaluation and follow-up are necessary to reduce cardiovascular risks and mortality of these patients.

Reference values of vessel diameters, stenosis prevalence, and arterial variations of the lower limb arteries in a male population sample using contrast-enhanced MR angiography.

IntroductionMorphological characterization of leg arteries is of significant importance to detect vascular remodeling triggered by atherosclerotic changes. We determined reference values of vessel diameters and assessed prevalence of stenosis and arterial variations of the lower limb arteries in a healthy male population sample.MethodsGadolinium-enhanced magnetic resonance angiography at 1.5 Tesla was performed in 756 male participants (median age = 52 years, range = 21–82 years) of the population-based Study of Health in Pomerania. Vessel diameters were measured in 9 predefined segments of the pelvic and leg arteries and 95th percentiles were used for upper reference values of means of left and right side arteries.ResultsReference values of vascular diameters decreased from proximal to distal arteries: common iliac = 1.18cm; internal iliac = 0.75cm; external iliac = 1.03cm; proximal femoral = 1.02cm; distal femoral = 0.77cm; popliteal = 0.69cm; anterior tibial = 0.42cm; posterior tibial = 0.38cm; fibular = 0.40cm. Body-surface area indexed reference values increased with age in all segments. A number of 53 subjects (7.0%) had at least one stenosis, mainly in the lower leg arteries anterior tibial (n = 28, 3.7%), posterior tibial (n = 18, 2.4%) and fibular (n = 20, 2.6%). The risk of stenosis increased considerably with age (odds ratio = 1.08; p<0.001). The most common arterial variant was type I-A in both legs (n = 620, 82%).ConclusionWe present reference values for different pelvic and leg artery segment diameters in men that decrease from proximal to distal and increase with age. Stenoses were most prevalent in lower leg arteries and type I-A was the most common variant in the lower leg.

Time-of-flight MR angiography in cerebral venous sinus thrombosis.

Recently, time-of-flight (TOF) and gadolinium-enhanced MR angiography (MRA) imaging have been used to demonstrate subacute intramural hematoma in cervical artery dissection and to detect intraplaque haemorrhage. Our aim was to perform an exploratory study to analyse if venous thrombus-related signal changes (potentially showing iso- or hyperintensity) in cerebral venous sinus thrombosis (CVST) could be observed on 3D-TOF MRA imaging. We analysed retrospectively MRIs of CVST patients in whom both contrast-enhanced MR venography (CEMRV) and 3D-TOF sequences were performed in the acute/subacute phase (i.e. <31days after symptom onset). The occluded sinus segments were defined on CEMRV. First, analyses of signal changes in occluded venous sinuses segments (defined by and unblinded to CEMRV) on native 3D-TOF images and morphological MRI sequences were performed. Second, a blinded (to CEMRV and other morphological MRI sequences) analysis was performed on 3D-TOF imaging assessing signal changes on 3D-TOF considering all sinus segments. Twenty-five CVST patients were included. 3D-TOF imaging showed signal changes (most often hyperintensity and less often isointensity) in 84% of the occluded sinus segments. Signal changes were observed in 91% of the occluded sinus segments on T1-weighted imaging, in 69% on T2-weighted imaging, in 68% on FLAIR, in 32% on DWI, and in 55% on T2*-weighted imaging. On blinded analysis, sensitivity of 3D-TOF sequences decreased to 80%, whereas specificity was only 65%. Abnormal signal in the venous sinuses on 3D-TOF may possibly help to suspect CVST, especially when CEMRV sequences lack.

The Role of Cardiovascular Magnetic Resonance in Congenital Heart Disease

The increasing prevalence of congenital heart disease (CHD) can be attributed to major improvements in diagnosis and treatment. Although echocardiography is the most commonly used imaging modality for diagnosis and follow up of subjects with CHD, the evolution of both cardiovascular magnetic resonance (MR) imaging and computed tomography (CT) does offer new ways to visualize the heart and the great vessels. The development of cardiovascular MR techniques such as spinecho and gradient-echo imaging, velocity-encoded phase contrast MR and gadolinium-enhanced MR angiography allow comprehensive assessment of cardiac anatomy and function. This provides information about the long-term sequelae of the underlying complex anatomy, hemodynamic assessment of residual post-operative lesions and complications of surgery. As much of the functional data in CHD patients is usually acquired with invasive X-ray angiography, non-invasive alternatives such as cardiovascular MR and CT are desirable. This review evaluates the role of both these modalities in the management of subjects with CHD, particularly detailing recent developments in imaging techniques as they relate to the various CHD diagnoses we commonly encounter in our practice.

Diagnostic value of contrast-enhanced magnetic resonance angiography in large-vessel vasculitis.

To evaluate contrast-enhanced magnetic resonance angiography (MRA) in diagnosis of inflammatory aortic involvement in patients with clinical suspicion of large-vessel vasculitis. Seventy-five patients, mean age 62 years (range 16-82 years), 44 female and 31 male, underwent gadolinium-enhanced MRA and were evaluated retrospectively. Thoracic MRA was performed in 32 patients, abdominal MRA in 7 patients and both thoracic and abdominal MRA in 36 patients. Temporal arterial biopsies were obtained from 22/75 patients. MRA positivity was defined as increased aortic wall signal in late gadolinium-enhanced axial turbo inversion recovery magnitude (TIRM) series. The influence of prior glucocorticoid intake on MRA outcome was evaluated. MRA was positive in 24/75 patients, with lesions located in the thorax in 7 patients, the abdomen in 5 and in both thorax and abdomen in 12. Probability for positive MRA after glucocorticoid intake for more than 5 days before MRA was reduced by 89.3%. Histology was negative in 3/10 MRA-positive patients and positive in 5/12 MRA-negative patients. All 5/12 histology positive / MRA-negative patients had glucocorticoids for >5 days prior to MRA and were diagnosed as having vasculitis. Positive predictive value for MRA was 92%, negative predictive value was 88%. Contrast-enhanced MRA reliably identifies large vessel vasculitis. Vasculitic signals in MRA are very sensitive to glucocorticoids, suggesting that MRA should be done before glucocorticoid treatment.

Feasibility of three-dimensional magnetic resonance angiography-fluoroscopy image fusion technique in guiding complex endovascular aortic procedures in patients with renal insufficiency

ObjectiveThree-dimensional image fusion of preoperative computed tomography (CT) angiography with fluoroscopy using intraoperative noncontrast cone-beam CT (CBCT) has been shown to improve endovascular procedures by reducing procedure length, radiation dose, and contrast media volume. However, patients with a contraindication to CT angiography (renal insufficiency, iodinated contrast allergy) may not benefit from this image fusion technique. The primary objective of this study was to evaluate the feasibility of magnetic resonance angiography (MRA) and fluoroscopy image fusion using noncontrast CBCT as a guidance tool during complex endovascular aortic procedures, especially in patients with renal insufficiency. MethodsAll endovascular aortic procedures done under MRA image fusion guidance at a single-center were retrospectively reviewed. The patients had moderate to severe renal insufficiency and underwent diagnostic contrast-enhanced magnetic resonance imaging after gadolinium or ferumoxytol injection. Relevant vascular landmarks electronically marked in MRA images were overlaid on real-time two-dimensional fluoroscopy for image guidance, after image fusion with noncontrast intraoperative CBCT. Technical success, time for image registration, procedure time, fluoroscopy time, number of digital subtraction angiography (DSA) acquisitions before stent deployment or vessel catheterization, and renal function before and after the procedure were recorded. The image fusion accuracy was qualitatively evaluated on a binary scale by three physicians after review of image data showing virtual landmarks from MRA on fluoroscopy. ResultsBetween November 2012 and March 2016, 10 patients underwent endovascular procedures for aortoiliac aneurysmal disease or aortic dissection using MRA image fusion guidance. All procedures were technically successful. A paired t-test analysis showed no difference between preimaging and postoperative renal function (P = .6). The mean time required for MRA-CBCT image fusion was 4:09 ± 01:31 min:sec. Total fluoroscopy time was 20.1 ± 6.9 minutes. Five of 10 patients (50%) underwent stent graft deployment without any predeployment DSA acquisition. Three of six vessels (50%) were cannulated under image fusion guidance without any precannulation DSA runs, and the remaining vessels were cannulated after one planning DSA acquisition. Qualitative evaluation showed 14 of 22 virtual landmarks (63.6%) from MRA overlaid on fluoroscopy were completely accurate, without the need for adjustment. Five of eight incorrect virtual landmarks (iliac and visceral arteries) resulted from vessel deformation caused by endovascular devices. ConclusionsFerumoxytol or gadolinium-enhanced MRA imaging and image fusion with fluoroscopy using noncontrast CBCT is feasible and allows patients with renal insufficiency to benefit from optimal guidance during complex endovascular aortic procedures, while preserving their residual renal function.

Bilateral Supernumerary Kidney

A 28-year-old woman suffered from bilateral flank pain recently. She had a history of repeat urinary tract infection for more than 5 years. Physical examination revealed no abnormalities and laboratory workup showed urine leukocytosis. Intravenous urography demonstrated four collecting systems and four renal shadows (Fig. 1A). Voiding cystourethrography showed no vesicoureteric reflux. MRI confirmed four separate kidneys (Fig. 1B) with four collecting systems and individual renal capsules (Fig. 1C), indicating supernumerary kidneys rather than duplication. Bilateral hydronephrosis at lower positioned kidneys were noted. Under the diagnosis of bilateral supernumerary kidney with repeat infection, the patient received antibiotic treatment (250 mg b.i.d, ciprofloxacin tablet) for seven days. The symptoms subsided and close follow up was provided at the outpatient department. Fig. 1 Images of the kidneys. (A) Intravenous urography shows four renal shadows (arrows) with four separate collecting systems. (B) Coronal T2-weighted magnetic resonance image shows bilateral supernumerary kidneys (arrows). The lower-positioned kidneys are ... Bilateral cases are extremely rare, with only seven reported in the English literature to our knowledge (1), and only one report, a unilateral case, has presented magnetic resonance imaging (MRI) (2). Bilateral supernumerary kidney is formed by aberrant embryologic division of the nephrogenic cord into two metanephric blastemas. The treatment depends on symptoms and the function of the supernumerary kidney. A high incidence of hydronephrosis, stones, pyelonephritis, and malignant changes has been reported (3,4). This abnormality requires close follow-up, and nephrectomy is an option when complications occur. The renal capsule has linear low signal intensity on T2-weighted MRI image and we can trace the entire capsule in the three plane images, so in this way it is much better than CT imaging. MR urography with T2-weighted images can also correctly demonstrate the collecting system, regardless of the renal function, and is also superior to CT. Capsules and collecting systems are key findings for differentiating supernumerary kidneys from renal duplication. If a patient is being considered for nephrectomy, gadolinium-enhanced MR angiography is suggested.

Comparing the Diagnostic Accuracy of Contrast-Enhanced Computed Tomographic Angiography and Gadolinium-Enhanced Magnetic Resonance Angiography for the Assessment of Hemodynamically Significant Transplant Renal Artery Stenosis

To compare diagnostic accuracy of contrast-enhanced computed tomographic angiography (CTA) and gadolinium-enhanced magnetic resonance angiography (MRA) for the assessment of hemodynamically significant transplant renal artery stenosis (TRAS). After institutional review board approval, records of 27 patients with TRAS confirmed on digital subtraction angiography (DSA) were retrospectively reviewed. A total of 13 patients had MRA and 14 had CTA before DSA. Two board-certified fellowship-trained radiologists, one each from interventional radiology and body imaging blindly reviewed the DSA and CTA or MRA data, respectively. Sensitivity (SN), specificity (SP), positive predictive value, and negative predictive value of MRA and CTA were estimated using 50% stenosis as the detection threshold for significant TRAS. These parameters were compared between modalities using the Fisher exact test. Bias between MRA or CTA imaging and DSA was tested using the Wilcoxon signed-rank test. Two patients were excluded from the MRA group owing to susceptibility artifacts obscuring the TRAS. The correlation between MRA and DSA measurements of stenosis was r = 0.57 (95% CI:-0.02, 0.87; P = 0.052) and between CTA and DSA measurements was r = 0.63 (95% CI: 0.14, 0.87; P = 0.015); the difference between the 2 techniques was not significant (P = 0.7). Both imaging modalities tended to underestimate the degree of stenosis when compared with DSA. MRA group (SN and SP: 56% and 100%, respectively) and CTA group (SN and SP: 81% and 67%, respectively). There were no significant differences in detection performance between modalities (P>0.3 for all measures). We did not find that either modality had any advantage over the other in terms of measuring or detecting significant stenosis. Accordingly, MRA may be preferred over CTA after positive color Doppler ultrasound screening when not contraindicated owing to lack of ionizing radiation or nephrotoxic iodinated contrast. However, susceptibility of artifacts owing to surgical clips at the anastomosis may limit diagnostic utility of MRA as found in 2 of 13 patients. Trend towards no significant difference between the CTA and enhanced MRA in the detection of hemodynamically significant TRAS.

Performance de la 18FDG-TEP dans le dépistage de paragangliome chez des patients porteurs d’une mutation SDHx

ObjectiveTo evaluate the performance of 18FDG-PET/CT for detecting infra-clinic paraganglioma (PGL) in SDHx mutation carriers (relatives). Patients and methodsSixty-six patients, from 13 distinct families underwent a genetic testing on the SHD genes between 2003 and 2012. Among the 45 patients with a mutation, 30 with a 18FDG-PET performed at initial work-up were included in this retrospective study. A gadolinium-enhanced magnetic resonance angiography of the neck (angio-MR) was performed in all cases, a thoracoabdominal-pelvic contrast-enhanced computed tomography (TAP-CT) in 25 cases, a TAP-MR in 20 cases, a 123I-metaiodo-benzylguanidine scintigraphy (123I-MIBG) in 20 cases and a somatostatin receptor scintigraphy (SRS) in 20 cases. Gold standard was histologic or composite (confirmation by another imaging method and follow-up). ResultsA tumor was found in five subjects: 2 abdominal PGL, 1 pheochromocytoma and 2 PGL of the neck. The sensitivity of 18FDG-PET was 100 %, of SRS was 80 %, of 123I-MIBG was 60 % and of anatomical imaging (association between angio-MR of the neck and TAP-CT and/or TAP-MR) was 100 %. Three false positive lesions were described: 2 with the 18FDG-PET imaging and 1 with the TAP-MR technique. Conclusion18FDG-PET/CT is an excellent tool for screening SDHx relatives and should be completed by an angio-MR of the neck if suspicion of abnormality. Association of angio-MR of the neck and TAP-MR has the advantage of being a non-irradiating imaging method but with limited access in some countries.

Gadolinium-enhanced magnetic resonance angiography in brain death

Confirmatory tests for the diagnosis of brain death in addition to clinical findings may shorten observation time required in some countries and may add certainty to the diagnosis under specific circumstances. The practicability of Gadolinium-enhanced magnetic resonance angiography to confirm cerebral circulatory arrest was assessed after the diagnosis of brain death in 15 patients using a 1.5 Tesla MRI scanner. In all 15 patients extracranial blood flow distal to the external carotid arteries was undisturbed. In 14 patients no contrast medium was noted within intracerebral vessels above the proximal level of the intracerebral arteries. In one patient more distal segments of the anterior and middle cerebral arteries (A3 and M3) were filled with contrast medium. Gadolinium-enhanced MRA may be considered conclusive evidence of cerebral circulatory arrest, when major intracranial vessels fail to fill with contrast medium while extracranial vessels show normal blood flow.

Magnetic resonance angiography vs. angiography in tetralogy of Fallot

: To determine whether gadolinium-enhanced three-dimensional magnetic resonance angiography can provide a noninvasive alternative to diagnostic catheterization for evaluation of pulmonary artery anatomy in tetralogy of Fallot. Thirty-five consecutive patients with tetralogy of Fallot, who attended the cardiology outpatient department between January 2008 and December 2009, were included in the study. There were 21 males and 14 females, with a mean age of 9 ± 4.15 years (range, 3-21 years). Thirty-two patients had tetralogy of Fallot with varying severities of valvular and infundibular stenosis. Three patients had tetralogy of Fallot with pulmonary atresia. All patients underwent both cardiac catheterization with X-ray angiography and 3-dimensional magnetic resonance angiography within one month. Measurements of right and left pulmonary arteries and aortopulmonary collaterals were equal by both methods. There was a good correlation between magnetic resonance angiography and catheterization measurements of branch pulmonary arteries. Gadolinium-enhanced three-dimensional magnetic resonance angiography can be used as a reliable noninvasive alternative to X-ray cineangiography for delineation of pulmonary arterial anatomy in sick infants and young children, obviating the need for catheterization.

A popliteal artery entrapment syndrome after by-pass surgery.

A 36-year-old male was admitted to our radiology department with a presentation of claudication on the left side for two weeks after femoral artery to tibial artery by-pass surgery. Upon physical examination, the left leg appeared pale and cold. Left magnetic resonance angiography (MRA) with gadolinium was performed from the superficial femoral arteries through the proximal portion of the popliteal fossa. The images included the bilateral popliteal arteries during dorsiflexion, plantar extension and neutral positions. There appeared to be a left venous graft that was patent. It arose from the proximal popliteal artery and traveled to the anterior tibial artery. The graft was patent at the visualized aspect. There appeared to be a mild to moderate degree of stenosis of the popliteal artery in the neutral position. There was severe stenosis of the same segment of the popliteal artery during knee extension. The popliteal artery was compressed by the slip of the medial head of the gastrocnemius, which arose more laterally than normal (Figure 1 A–C). Figure 1. 3D gadolinium-enhanced MRA images reveal the mild degree of stenosis of the popliteal artery in the neutral and dorsiflexion positions (A, B); there is severe stenosis of the same segment of the popliteal artery in the extension position (C). These images ... Popliteal artery entrapment syndrome (PAES) is a rare congenital vascular pathology caused by a compression of the popliteal artery by adjacent muscle and tendon structures. This condition is most commonly observed in young men with ischemic symptoms of the lower extremities. Extrinsic arterial compression causes chronic vascular micro trauma, early arteriosclerosis and thrombus formation, leading to distal ischemia [1, 2]. The classic presentation, which includes calf or foot claudication or pain on exertion, can have many other etiologies, including atherosclerosis, exertional compartment syndrome, and other musculoskeletal or neurogenic disorders. The most commonly used classification of PAES was described by Love and Whalen [3]. Our case had type III PAES. The incidence of popliteal entrapment has been described to be between 0.165% and 3.5% [2, 4]. Noninvasive tests, such as duplex ultrasound and axial imaging, including multi detector computed tomography angiography (MDCTA) or MRA, can help identify the anatomical abnormalities [1, 4]. In conclusion, MRA MDCTA is a safe, rapid, and noninvasive diagnostic imaging technique that enables clinicians to determine the underlying pathology and the complications of PAES.

Unenhanced 3D Turbo Spin-Echo MR Angiography of Lower Limbs in Peripheral Arterial Disease: A Comparative Study With Gadolinium-Enhanced MR Angiography

The purpose of this study was to assess the feasibility and diagnostic performance of an unenhanced MR angiography sequence (Syngo Native Space, Siemens Healthcare) to detect and quantify lower-limb peripheral arterial disease (PAD), with gadolinium-enhanced MR angiography (CE-MRA) as the reference standard. Fifty-one patients known to have lower-limb arteriopathy were included in this prospective study. For every patient, we performed Native sequence and CE-MRA on a 1.5-T system. We evaluated examination duration, image quality, and location, number, and severity of lesions. Examination duration was longer for Native sequence (mean, 39.6 min, vs 10 min for CE-MRA). Image quality was significantly better for CE-MRA, with 92% of images listed as good to excellent for CE-MRA, compared to 53% for Native. Sensitivity, specificity, negative predictive value (NPV), and accuracy of Native were respectively 75%, 95%, 89%, and 88% for all mixed levels; 52%, 97%, 88%, and 87% for aortoiliac level; 87%, 99%, 95%, and 92% for femoropopliteal level; and 82%, 87%, 87%, and 85% for subpopliteal level. If we considered only patients with Leriche and Fontaine stage II arteriopathy, Native results were slightly better, with respective specificities and NPVs of 96% and 91% for all mixed levels; 98% and 90% for aortoiliac level; 98% and 93% for femoropopliteal level; and 91% and 90% for subpopliteal level. Unenhanced MR angiography, cheaper than CE-MRA, showed in our study a good NPV, which suggests its utility as first-line test to screen for PAD, especially in patients at risk of nephrogenic systemic fibrosis.

946Free breathing 3D-navigator-guided, gadolinium-enhanced magnetic resonance angiography of pulmonary veins and the impact of heart rate and rhythm on image quality

946Free breathing 3D-navigator-guided, gadolinium-enhanced magnetic resonance angiography of pulmonary veins and the impact of heart rate and rhythm on image quality

Nephrogenic Systemic Fibrosis in a Patient With Renal Failure Demonstrating a “Reverse Superscan” on Bone Scintigraphy

Nephrogenic systemic fibrosis (NSF) has been linked to utilization of gadolinium-based contrast agents in patients with renal impairment. We present a 19-year-old female patient with end-stage renal failure presenting with joint pains and subcutaneous nodules. She had a prior gadolinium-enhanced magnetic resonance angiography when she was 14 years old. Clinical findings revealed firm subcutaneous nodules in both thighs. Whole-body bone scan demonstrates tracer uptake predominantly in the soft tissues and muscles of the extremities with minimal bony uptake. Incisional biopsy of the left thigh nodule revealed features of NSF with a total pathological score of 4, highly consistent with NSF.