MR angiography of the pedal arteries with gadobenate dimeglumine, a contrast agent with increased relaxivity, and comparison with selective intraarterial DSA

PURPOSE: To compare gadobenate dimeglumine (Gd-BOPTA)-enhanced MR angiography (i.e., contrast-enhanced MRA [CE-MRA]) of the pedal vasculature with selective digital subtraction angiography (DSA) in patients with peripheral arterial occlusive disease (PAOD). MATERIALS AND METHODS: A total of 22 patients with PAOD were prospectively examined at 1.5T. For contrast enhancement, 0.1 mmol/kg body weight of Gd-BOPTA were applied. MRA consisted of dynamic imaging with acquisition of six consecutive data sets. Acquisition time for each data set was 24 seconds, voxel size was 1.0 x 1.0 x 1.3 mm(3). A total of 20 out of 22 patient underwent selective DSA, two patients fine-needle DSA. DSA and MRA were performed within seven days. Image analysis was independently done by two observers with assessment of overall image quality, motion artifacts, detection of patent vessel segments of the distal calf and pedal vessels, and the number of patent metatarsal arteries. After four weeks, a consensus reading of DSA images was done. A second consensus reading of CE-MRA was performed after a further six weeks. RESULTS: Consensus readings of MRA and DSA revealed higher image quality and fewer motion artifacts for MRA (P = 0.021 and P = 0.008, respectively, sign test); interobserver agreement was good (kappa = 0.78) for image quality, and moderate (kappa = 0.46) for motion artifacts. There were no differences between CE-MRA and DSA in detecting patent vessel segments with a high degree of agreement (kappa = 0.89), and interobserver agreement for MRA was substantial (kappa = 0.89). Significantly more vessels were assessed as partially occluded on DSA than on CE-MRA (P = 0.004). There was a good agreement between DSA and CE-MRA for assessment of relevant vessel stenosis (kappa = 0.61); interobserver agreement for MRA was good (kappa = 0.65). CE-MRA detected significantly more patent metatarsal arteries than did DSA (P < 0.001). CONCLUSION: Gd-BOPTA-enhanced MRA is comparable to DSA for assessment of the pedal vasculature, and is able to delineate significantly more patent vessels without segmental occlusions and more metatarsal arteries than selective DSA.     

Triple-TWIST MRA: high spatial and temporal resolution MR angiography of the entire peripheral vascular system using a time-resolved 4D MRA technique

Objectives

Multi-station contrast-enhanced magnetic resonance angiography (MRA) is considered as the imaging investigation of first choice in patients suffering from peripheral arterial occlusive disease. In order to overcome venous overlay and to gain dynamic flow information as provided by digital subtraction angiography (DSA), we developed a triple injection protocol for high-resolution MRA of the entire peripheral vascular system, applying time-resolved (TR) four-dimensional (4D) MRA sequences.

Methods

Ten patients underwent three-station TR-MRA of the pelvis and lower extremities with DSA as reference standard. Both investigations were compared concerning stenosis on a segment-by-segment basis. Furthermore, 28 consecutive patients underwent the same MR-only imaging protocol. All images were evaluated concerning image quality (1 = non-diagnostic, 4 = excellent), venous overlay (from none up to substantial) and time to venous enhancement (very early/early/normal/late).

Results

Three-station TR-MRA proved feasible and was comparable with DSA in 282 vessel segments, with underestimation grade of stenosis in four segments and overestimation in four segments, respectively. In 32/38 patients no venous overlay was noted; in six patients there was mild venous overlay. Image quality was rated excellent or good in most cases.

Conclusions

TR-MRA provides morphological and functional information without any timing issues due to optimal arterial enhancement at high spatial resolution without venous overlay.

Key Points

? Contrast-enhanced MR angiography (MRA) has become widely accepted. ? Time-resolved (TR) MRA provides dynamic arterial flow information without venous overlay. ? TR-MRA and DSA show comparable results for assessment of stenosis. ? TR-MRA provides excellent-good image quality of the peripheral vascular system.     

Thrombus imaging in acute stroke: correlation of thrombus length on susceptibility-weighted imaging with endovascular reperfusion success

Objectives

Susceptibility-weighted imaging (SWI) enables visualization of thrombotic material in acute ischemic stroke. We aimed to validate the accuracy of thrombus depiction on SWI compared to time-of-flight MRA (TOF-MRA), first-pass gadolinium-enhanced MRA (GE-MRA) and digital subtraction angiography (DSA). Furthermore, we analysed the impact of thrombus length on reperfusion success with endovascular therapy.

Methods

Consecutive patients with acute ischemic stroke due to middle cerebral artery (MCA) occlusions undergoing endovascular recanalization were screened. Only patients with a pretreatment SWI were included. Thrombus visibility and location on SWI were compared to those on TOF-MRA, GE-MRA and DSA. The association between thrombus length on SWI and reperfusion success was studied.

Results

Eighty-four of the 88 patients included (95.5 %) showed an MCA thrombus on SWI. Strong correlations between thrombus location on SWI and that on TOF-MRA (Pearson’s correlation coefficient 0.918, P?<?0.001), GE-MRA (0.887, P?<?0.001) and DSA (0.841, P?<?0.001) were observed. Successful reperfusion was not significantly related to thrombus length on SWI (P?=?0.153; binary logistic regression).

Conclusions

In MCA occlusion thrombus location as seen on SWI correlates well with angiographic findings. In contrast to intravenous thrombolysis, thrombus length appears to have no impact on reperfusion success of endovascular therapy.

Key Points

? SWI helps in assessing location and length of thrombi in the MCA ? SWI, MRA and DSA are equivalent in detecting the MCA occlusion site ? SWI is superior in identifying the distal end of the thrombus ? Stent retrievers should be deployed over the distal thrombus end ? Thrombus length did not affect success of endovascular reperfusion guided by SWI     

Accuracy of 3 T MR angioraphy in vertebral artery stenosis and coincidence with other cerebrovascular stenoses

Introduction

Ostium of vertebral artery (VA) is a common site of pseudostenosis on contrast-enhanced MR angiography (CE-MRA). The purpose of this study was to determine the diagnostic accuracy of CE-MRA at 3 T in the evaluation of ostial stenosis of VA and to find associated coincidental stenoses using logistic regression analysis.

Methods

One hundred and thirty-five VA ostial regions from 72 patients who received CE-MRA of neck vessels, intracranial time of flight (TOF) MRA, and digital subtraction angiography (DSA) were retrospectively reviewed. The sensitivity and specificity of the CE-MRA in detection of ostial stenosis were calculated with reference standard of DSA. Ostial stenosis on MRA was correlated with coincidental lesions in intracranial and cervical arteries by logistic regression analysis.

Results

The sensitivity and specificity of the CE-MRA were 100% and 80.4% for detection of significant stenosis. In case of significant stenoses, CE-MRA showed a tendency of overestimation with a false-positive rate of 52.5%. Logistic regression analysis showed that the stenoses of middle cerebral artery (MCA) on TOF MRA was associated with significant stenoses of VA ostia (OR?=?5.84, 95% confidence intervals 1.41–24.17).

Conclusion

CE-MRA is sensitive in detection of VA ostial stenosis although it has high false-positive rate. True positive ostial stenosis should be considered in cases of coincidental stenoses of MCA on TOF MRA.     

Whole-body magnetic resonance angiography for presurgical planning of free-flap head and neck reconstruction

Objectives

Aim of the study was to evaluate if a whole-body magnetic resonance angiography (MRA) protocol meets the requirements to evaluate the donor and host site target vessels for planning of microvascular head and neck reconstructions.

Patients and methods

In 20 patients, scheduled for reconstruction of the mandible with fibular free flaps, contrast-enhanced whole-body MRA was performed prior to surgery. 32-Channel 1.5-T MR angiograms were acquired using a 2-step contrast (gadobutrol) injection scheme to visualize the arterial vasculature from head to feet. Maximum intensity projection and multiplanar reconstruction technique was employed to visualize MRA data. For image evaluation the arterial tree was divided into 51 segments. The presence of artefacts impairing diagnostic quality was noted. Evaluable segments were assessed regarding the presence of stenoses >50% diameter reduction, occlusions or aneurysms.

Results

No adverse reactions or complications occurred. Of 1020 vessel segments 1003 (98.3%) were evaluable. 36 stenoses >50%, 50 occlusions and one aneurysm were observed. In 21 of 40 lower limbs relevant atherosclerotic changes were depicted.

Conclusion

Whole-body MRA proved to be a suitable three-dimensional, noninvasive, nonionising modality for preoperative evaluation of the entire arterial vasculature.     

Magnetic resonance angiography in infrapopliteal arterial disease: prospective comparison of 1.5 and 3 Tesla magnetic resonance imaging

PURPOSE: To prospectively determine the accuracy of 1.5 Tesla (T) and 3 T magnetic resonance angiography (MRA) versus digital subtraction angiography (DSA) in the depiction of infrageniculate arteries in patients with symptomatic peripheral arterial disease. PATIENTS AND METHODS: A prospective 1.5 T, 3 T MRA, and DSA comparison was used to evaluate 360 vessel segments in 10 patients (15 limbs) with chronic symptomatic peripheral arterial disease. Selective DSA was performed within 30 days before both MRAs. The accuracy of 1.5 T and 3 T MRA was compared with DSA as the standard of reference by consensus agreement of 2 experienced readers. Signal-to-noise ratios (SNR) and signal-difference-to-noise ratios (SDNRs) were quantified. RESULTS: No significant difference in overall image quality, sufficiency for diagnosis, depiction of arterial anatomy, motion artifacts, and venous overlap was found comparing 1.5 T with 3 T MRA (P > 0.05 by Wilcoxon signed rank and as by Cohen k test). Overall sensitivity of 1.5 and 3 T MRA for detection of significant arterial stenosis was 79% and 82%, and specificity was 87% and 87% for both modalities, respectively. Interobserver agreement was excellent k > 0.8, P < 0.05) for 1.5 T as well as for 3 T MRA. SNR and SDNR were significantly increased using the 3 T system (average increase: 36.5%, P < 0.032 by t test, and 38.5%, P < 0.037 respectively). CONCLUSIONS: Despite marked improvement of SDNR, 3 T MRA does not yet provide a significantly higher accuracy in diagnostic imaging of atherosclerotic lesions below the knee joint as compared with 1.5 T MRA.     

Patency of runoff detected by MR angiography at 3.0 T with cuff-compression: a predictor of successful endovascular recanalization below the knee

Objectives

Our aim was to assess the reliability of detecting distal runoff vessels using contrast-enhanced MR angiography (CE-MRA) that were occult on digital subtraction angiography (DSA) for predicting the outcome of endovascular recanalization (ER).

Methods

This retrospective analysis comprised 63 patients with diabetes (98 limbs) who underwent ER for infrapopliteal lesions. Before ER, they underwent CE-MRA and DSA for peripheral arterial disease; runoff vessels were detected with CE-MRA, but not with DSA. Immediate and follow-up postoperative outcomes were assessed. Univariate analysis was performed to identify variables associated with successful ER.

Results

Successful ER was achieved in 85.7 % of limbs, and runoff score was significantly lower than in failure limbs (5.1?±?1.1 vs. 6.2?±?1.3; P?Restenosis/occlusion rate was higher for patients with CLI at 12 months (48.8 % vs. 96.3 % in claudication; P?P?Conclusion Runoff vessels detected using CE-MRA could indicate immediate success and better outcome of ER for infrapopliteal occlusions.

Key Points

? 3-T MRA with cuff compression displayed distal below-the-knee (BTK) runoffs better than DSA ? Detected runoffs indicate high recanalization rate and good clinical outcome ? Runoff display provides potential opportunity to perform other backup recanalization strategies     

Nonenhanced ECG-gated time-resolved 4D Steady-state free precession (SSFP) MR angiography (MRA) for assessment of cerebral collateral flow: comparison with digital subtraction angiography (DSA)

Objectives

To evaluate a nonenhanced time-resolved 4D SSFP MRA for dynamic visualization of intracranial collateral blood flow.

Methods

22 patients (59.0?±?11.8 years) with steno-occlusive disease of brain-supplying arteries were included in this study. 4D SSFP MRA of the intracranial arteries was acquired with 15 temporal phases and a temporal resolution of 115 ms using 1.5 T MR. Cerebral DSA served as the reference standard and was available in all patients.

Results

Nonenhanced 4D SSFP MRA allowed for detailed dynamic visualization of blood flow in the circle of Willis and its branches in 21 of 22 (95.5%) patients. Collateral flow was excluded with both 4D SSFP MRA and DSA in 4 patients. In 17 patients, DSA detected anterior collateral flow (n?=?8), posterior collateral flow via the right (n?=?8) and left (n?=?7) posterior communicating artery as well as patent EC-IC bypasses (n?=?8). 29 of 31 collateral flow pathways were visualized by 4D SSFP MRA. As compared to DSA, 4D SSFP MRA showed a high sensitivity (92.3%), specificity (100%), positive predictive value (100%) and negative predictive value (95.2%) for visualization of intracranial collateral flow.

Conclusions

4D SSFP MRA is a promising non-invasive imaging technique for dynamic visualization of intracranial collateral flow.     

ECG-Triggered Non-Contrast-Enhanced MR Angiography (TRANCE) versus Digital Subtraction Angiography (DSA) in patients with peripheral arterial occlusive disease of the lower extremities

Objective

To prospectively determine the diagnostic value of electrocardiography-triggered non-contrast-enhanced magnetic resonance angiography (TRANCE) of the lower extremities including the feet versus DSA.

Methods

All 43 patients with symptomatic peripheral arterial occlusive disease (PAOD) underwent TRANCE before DSA. Quality of MRA vessel depiction was rated by two independent radiologists on a 3-point scale. Arterial segments were graded for stenoses using a 4-point scale (grade 1: no stenosis; grade 2: moderate stenosis; grade 3: severe stenosis; grade 4: occlusion). Findings were compared with those of DSA.

Results

In the 731 vessel segments analysed, intra-arterial DSA revealed 283 stenoses: 33.6% moderate, 16.6% severe and 49.8% occlusions. TRANCE yielded a mean sensitivity, specificity, positive and negative predictive value and diagnostic accuracy to detect severe stenoses or occlusions of 95.6%, 97.4%, 87.2%, 99.2%, 97.1% for the thigh segments and 95.2%, 87.5%, 83.2%, 96.6%, 90.5% for the calf segments. Excellent overall image quality was observed for TRANCE in 91.4% versus 95.7% (DSA) for the thigh and in 60.7% versus 91.0% for the calves, while diagnostic quality of the pedal arteries was rated as insufficient.

Conclusion

TRANCE achieves high diagnostic accuracy in the thigh and calf regions, whereas the pedal arteries showed limited quality.     

Detection of Malignant Primary Hepatic Neoplasms with Gadobenate Dimeglumine (Gd-BOPTA) Enhanced T1-Weighted Hepatocyte Phase MR Imaging: Results of Off-site Blinded Review in a Phase-II Multicenter Trial

Objective

To investigate the efficacy of gadobenate dimeglumine (Gd-BOPTA) enhanced MR imaging for the detection of liver lesions in patients with primary malignant hepatic neoplasms.

Materials and Methods

Thirty-one patients with histologically proven primary malignancy of the liver were evaluated before and after administration of Gd-BOPTA at dose 0.05 or 0.10 mmol/kg. T1-weighted spin echo (T1W-SE) and gradient echo (T1W-GRE) images were evaluated for lesion number, location, size and confidence by three off-site independent reviewers and the findings were compared to reference standard imaging (intraoperative ultrasound, computed tomography during arterial portography or lipiodol computed tomography). Results were analyzed for significance using a two-sided McNemar''s test.

Results

More lesions were identified on Gd-BOPTA enhanced images than on unenhanced images and there was no significant difference in lesion detection between either concentration. The largest benefit was in detection of lesions under 1 cm in size (7 to 21, 9 to 15, 16 to 18 for reviewers A, B, C respectively). In 68% of the patients with more than one lesion, Gd-BOPTA increased the number of lesions detected.

Conclusion

Liver MR imaging after Gd-BOPTA increases the detection of liver lesions in patients with primary malignant hepatic neoplasm.     

Whole-body MR angiography using a novel 32-receiving-channel MR system with surface coil technology: first clinical experience

PURPOSE: To demonstrate the feasibility of detecting atherosclerotic vascular disease using an innovative magnetic resonance angiography (MRA) protocol in combination with a dedicated whole-body MR scanner with new surface coil technology. MATERIALS AND METHODS: A total of 10 volunteers and eight patients with peripheral arterial occlusive disease (PAOD) were examined at 1.5 T. Conventional digital subtraction angiography (DSA) of the symptomatic region was available as a reference standard in all eight patients. Depending on subjects' size, four to five three-dimensional data sets were acquired using an adapted injection protocol. Images were assessed independently by two readers for vascular pathology. Additionally, signal-to-noise ratios (SNRs) and contrast-to-noise ratios (CNRs) were measured. RESULTS: Whole-body MRA yielded excellent sensitivity and specificity of more than 95% for both readers with high interobserver agreement (k = 0.93). Surface coil signal reception rendered a high SNR (mean 151.28 +/- 54.04) and CNR (mean 120.75 +/- 46.47). Despite lower SNR and CNR of the cranial and cervical vessels, a two-step injection protocol exhibited less venous superposition and therefore proved to be superior compared to single-bolus injection. CONCLUSION: Our approach provides accurate noninvasive high-resolution imaging of systemic atherosclerotic disease, covering the arterial vasculature from intracranial arteries to distal runoff vessels. The recently introduced MR scanner and coil technology is feasible to significantly increase the performance of whole-body MRA.     

Role of whole-body diffusion-weighted MRI in detecting bone metastasis

Purpose

The aim of this study was to compare the results of whole-body diffusion-weighted magnetic resonance (DW-MR) imaging with staging based on computed tomography (CT) and nuclear scintigraphy using Tc99m results as the standard of reference.

Methods and materials

Seventeen patients with known malignant tumours were included in the study. The thorax and the abdomen were imaged using breath-hold diffusion-weighted imaging and T1-weighted imaging sequences in the coronal plane. Location and size of osseous metastases were documented by two experienced radiologists. Whole-body DW-MR imaging findings were compared with results obtained at skeletal scintigraphy and CT bone survey.

Results

The mean examination time for whole-body DW-MR imaging was 25.5 min. All bone metastases regardless of the size were identified with whole-body DW-MR imaging; MR imaging depicted more bone metastases than CT. Skeletal scintigraphy depicted osseous metastases in 13 patients (with greater sensitivity to the lower limb), whereas whole-body DW-MR imaging revealed osseous metastases in 13 patients (with greater sensitivity to the spine). DW-MR did not show good results for detection of rib cage metastases. The additional osseous metastases seen with MR imaging were confirmed at follow-up examinations and some had a change in therapy. MR identified 22 % more metastatic lesions when compared to bone scintigraphy and 119 % when compared to CT. Bone scintigraphy identified 80 % more metastatic lesions when compared to CT. On a per-patient basis, whole-body DW-MR imaging revealed sensitivity and specificity values of 100 %.

Conclusion

Whole-body DW-MR imaging was more sensitive in the detection of osseous metastases than were skeletal scintigraphy and CT bone survey.     

Peripheral arterial disease. Contrast-enhanced 3D MR angiography of the lower leg and foot compared with conventional angiography

PURPOSE: To determine whether contrast-enhanced 3D MR angiography (CE MRA) could replace digital subtraction angiography (DSA) for the evaluation of atherosclerotic peripheral vascular disease of the lower leg and foot. MATERIAL AND METHODS: Thirty-five patients with symptoms of atherosclerotic disease of the leg were examined prospectively with CE MRA of the foot and the lower legs as well as with DSA from the aorta to the pedal arches. The MRA technique was focused on optimal imaging of the arteries of the foot. RESULTS: The agreement between CE MRA and DSA for grading of stenosis was moderate to good (weighted kappa-values 0.48-0.80). The sensitivity of CE MRA for detection of significant stenosis (> or = 50%) was 92% and the specificity was 64% with DSA as gold standard. CONCLUSION: CE MRA is a fairly accurate method for the demonstration of atherosclerotic disease below the knee including the pedal arches. It can replace DSA for the assessment of distal arteries in patients with impaired renal function. However, image quality and resolution still needs to be improved before CE MRA can become the method of choice in all patients.     

Comparison between 64-row CT angiography and digital subtraction angiography in the study of lower extremities: personal experience

Purpose

This study was undertaken to evaluate the potential of 64-row multislice computed tomography (CT) versus digital subtraction angiography (DSA) in detecting significant lesions of lower-extremity inflow and runoff arteries.

Materials and methods

Fifty-three patients underwent 64-row multislice CT and DSA over a mean of 36 days. The vascular tree was divided into 33 segments. Three readers independently reviewed the axial CT scans and multiplanar oblique and two- and three-dimensional reconstructions (maximum intensity projection and volume rendering) images to assess degree of stenosis according to four categories: 1 (0%–49% stenosis); 2 (50%–99% stenosis); 3 (occluded); 4 (not evaluable). In all cases, DSA was performed by arterial catheterisation.

Results

In 53 patients, 1,440 segments were evaluated (infrarenal aorta and 16 arterial segments for each leg; 42 bilateral studies, 11 unilateral studies). Compared with DSA, CT angiography yielded 97.2% sensitivity, 97% specificity, 92.5% positive predictive value, 98.9% negative predictive value, 97.1% diagnostic accuracy and 95.4% concordance on the degree of stenosis.

Conclusions

Sixty-four-row multislice CT proved to be helpful in detecting haemodynamically significant lesions in peripheral arterial occlusive disease and improved the results obtained with 4- and 16-slice multidetector CT. In addition, owing to the high spatial resolution and rigorous technique, no variations in the data obtained below the knee were detected, overcoming a limitation of earlier generations of CT scanners.     

The value of magnetic resonance imaging for the detection of the bleeding source in non-traumatic intracerebral haemorrhages: a comparison with conventional digital subtraction angiography

Introduction

Conventional digital subtraction angiography (DSA) is currently regarded as the gold standard in detecting underlying vascular pathologies in patients with intracerebral haemorrhages (ICH). However, the use of magnetic resonance imaging (MRI) in the diagnostic workup of ICHs has considerably increased in recent years. Our aim was to evaluate the diagnostic accuracy and yield of MRI for the detection of the underlying aetiology in ICH patients.

Methods

Sixty-seven consecutive patients with an acute ICH who underwent MRI (including magnetic resonance angiography (MRA) and DSA during their diagnostic workup) were included in the study. Magnetic resonance images were retrospectively analysed by two independent neuroradiologists to determine the localisation and cause of the ICH. DSA was used as a reference standard.

Results

In seven patients (10.4%), a DSA-positive vascular aetiology was present (one aneurysm, four arteriovenous malformations, one dural arteriovenous fistula and one vasculitis). All of these cases were correctly diagnosed by both readers on MRI. In addition, MRI revealed the following probable bleeding causes in 39 of the 60 DSA-negative patients: cerebral amyloid angiopathy (17), cavernoma (9), arterial hypertension (8), haemorrhagic transformation of an ischaemic infarction (3) and malignant brain tumour with secondary ICH (2).

Conclusion

Performing MRI with MRA proved to be an accurate diagnostic tool in detecting vascular malformations in patients with ICH. In addition, MRI provided valuable information regarding DSA-negative ICH causes, and thus had a high diagnostic yield in ICH patients.     

Follow-up of coiled intracranial aneurysms: comparison of 3D time-of-flight and contrast-enhanced magnetic resonance angiography at 3T in a large, prospective series

Objectives

To compare 3D-TOF magnetic resonance angiography (MRA) and contrast-enhanced MRA (CE-MRA) sequences at 3T in the follow-up of coiled aneurysms with digital subtracted angiography (DSA) as the gold standard.

Methods

DSA, 3D-TOF and CE-MRA were performed in a prospective series of 126 aneurysms in 96 patients (57 female, 39 male; age: 25–75 years, mean: 51.3?±?11.3 years). The quality of aneurysm occlusion was assessed independently and anonymously by a core laboratory.

Results

Using DSA (gold standard technique), total occlusion was depicted in 57 aneurysms (45.2%), neck remnant in 34 aneurysms (27.0%) and aneurysm remnant in 35 aneurysms (27.8%). Sensitivity, specificity, positive predictive value and negative predictive value were very similar with 3D-TOF and CE-MRA. Visibility of coils was much better with 3D-TOF (95.2%) than with CE-MRA (23.0%) (P?P?=?0.012).

Conclusions

In this large prospective series of patients with coiled aneurysms, at 3T 3D-TOF MRA was equivalent to CE-MRA for the evaluation of aneurysm occlusion, but coil visibility was superior at 3D-TOF. Thus the use of 3D-TOF at 3T is recommended for the follow-up of coiled intracranial aneurysms.

Key Points

? Different Magnetic Resonance (MR) imaging techniques are used to evaluate intracranial aneurysms. ? At 3T MR, 3D-TOF and CE-MRA appear equivalent for evaluating coiled aneurysms.. ? Coils are better visualised on 3D-TOF than on CE-MRA. ? Combined analysis of 3D-TOF and CE-MRA does not seem helpful. ? At 3T, 3D-TOF techniques are recommended for monitoring patients with coiled aneurysms.     

First-pass contrast-enhanced renal MRA at 7 Tesla: initial results

Objective

The aim of this study was to assess the feasibility of first-pass contrast-enhanced renal MR angiography (MRA) at 7 T.

Methods

In vivo first-pass contrast-enhanced high-field examinations were obtained in eight healthy subjects on a 7-T whole-body MRI. A custom-built body transmit/receive radiofrequency (RF) coil and RF system suitable for RF shimming were used for image acquisition. For dynamic imaging, gadobutrol was injected intravenously and coronal unenhanced, arterial and venous data sets using a T1-weighted spoiled gradient-echo sequence were obtained. Qualitative image analysis and assessment of artefact impairment were performed by two senior radiologists using a five-point scale (5 = excellent, 1 = non-diagnostic). SNR and CNR of the perirenal abdominal aorta and both main renal arteries were assessed.

Results

Qualitative image evaluation revealed overall high-quality delineation of all assessed segments of the unenhanced arterial vasculature (mean_unenhanced 4.13). Nevertheless, the application of contrast agent revealed an improvement in vessel delineation of all the vessel segments assessed, confirmed by qualitative (mean_unenhanced 4.13 to mean_{contrast-enhanced} 4.85) and quantitative analysis (SNR mean_unenhanced 64.3 to mean_{contrast-enhanced} 98.4).

Conclusion

This study demonstrates the feasibility and current constraints of ultra-high-field contrast-enhanced renal MRA relative to unenhanced MRA.

Key Points

? First-pass contrast-enhanced renal MRA at 7 T is technically feasible. ? Unenhanced renal MRA offers inherent hyperintense delineation of renal arterial vasculature. ? Contrast media application improves vessel assessment of renal arteries at 7 T.     

MRI of intracranial vertebral artery dissection: evaluation of intramural haematoma using a black blood, variable-flip-angle 3D turbo spin-echo sequence

Introduction

We investigated the efficacy of three-dimensional black blood T1-weighted imaging (3D-BB-T1WI) using a variable refocusing flip angle turbo spin-echo sequence in the diagnosis of intracranial vertebral artery dissection (VAD).

Methods

Sixteen consecutive patients diagnosed with intracranial VAD underwent magnetic resonance imaging that included 3D time-of-flight-MRA, axial spin-echo T1-weighted images (SE-T1WI) and oblique coronal 3D-BB-T1WI sequences. The visualization, morphology and extent of intramural haematomas were assessed and compared among the sequences. Results obtained by digital subtraction angiography (DSA), 3D-angiography and/or 3D-CT angiography (CTA) were used as standards of reference.

Results

3D-BB-T1WI revealed intramural haematomas in all cases, whereas SE-T1WI and magnetic resonance angiography (MRA) failed to reveal a haematoma in one case and three cases, respectively. The mean visualization grading score for the intramural haematoma was the highest for 3D-BB-T1WI, and there was a statistically significant difference among the sequences (p?<?0.001). At least a portion of the intramural haematoma was distinguishable from the lumen on 3D-BB-T1WI, whereas the haematomas were entirely indistinguishable from intraluminal signals on MRA in two cases (12.5 %) and on SE-T1WI in one case (6.3 %). 3D-BB-T1WI revealed the characteristic crescent shape of the intramural haematoma in 14 cases (87.5 %), whereas SE-T1WI and MRA revealed a crescent shape in only 7 cases (43.8 %) and 8 cases (50 %), respectively. In a consensus reading, 3D-BB-T1WI was considered the most consistent sequence in representing the extent and morphology of the lesion in 14 cases (87.5 %), compared to DSA and CTA.

Conclusion

3D-BB-T1WI is a promising method to evaluate intramural haematoma in patients with suspected intracranial VAD.     

Accuracy of magnetic resonance imaging, magnetic resonance arthrography and computed tomography for the detection of chondral lesions of the knee

Purpose

To assess the diagnostic test accuracy of magnetic resonance imaging (MRI), magnetic resonance arthrography (MRA) and computed tomography arthrography (CTA) for the detection of chondral lesions of the patellofemoral and tibiofemoral joints.

Methods

A review of published and unpublished literature sources was conducted on 22nd September 2011. All studies assessing the diagnostic test accuracy (sensitivity/specificity) of MRI or MRA or CTA for the assessment of adults with chondral (cartilage) lesions of the knee (tibiofemoral/patellofemoral joints) with surgical comparison (arthroscopic or open) as the reference test were included. Data were analysed through meta-analysis.

Results

Twenty-seven studies assessing 2,592 knees from 2,509 patients were included. The findings indicated that whilst presenting a high specificity (0.95?C0.99), the sensitivity of MRA, MRI and CTA ranged from 0.70 to 0.80. MRA was superior to MRI and CTA for the detection of patellofemoral joint chondral lesions and that higher field-strength MRI scanner and grade four lesions were more accurately detected compared with lower field-strength and grade one lesions. There appeared no substantial difference in diagnostic accuracy between the interpretation from musculoskeletal and general radiologists when undertaking an MRI review of tibiofemoral and patellofemoral chondral lesions.

Conclusions

Specialist radiological imaging is specific for cartilage disease in the knee but has poorer sensitivity to determine the therapeutic options in this population. Due to this limitation, there remains little indication to replace the ??gold-standard?? arthroscopic investigation with MRI, MRA or CTA for the assessment of adults with chondral lesions of the knee.

Level of evidence

II.     

Contrast-enhanced MR angiography of the carotid and vertebrobasilar circulations

BACKGROUND AND PURPOSE: Contrast-enhanced MR angiography (CE MRA) is a proven diagnostic tool in evaluation of the carotid arteries; however, few studies have addressed its accuracy in the vertebrobasilar system. The purpose of this study was to assess the sensitivity and specificity of CE MRA compared with digital subtraction angiography (DSA) for detection of vertebrobasilar disease. METHODS: Forty patients with suspected atherosclerotic disease of the carotid and vertebrobasilar circulations underwent CE MRA on a 1.5 T MR imaging scanner by use of a coronal 3D gradient-echo pulse sequence after intravenous injection of gadolinium diethylene triamine penta-acetic acid. All patients had correlative DSA within a 1-month period. CE MRA images were randomized and then independently assessed by 2 observers who were blinded to the DSA results. DSA examinations were analyzed in a similar manner. Each observer was asked to report the presence or absence of clinically significant stenosis (>50%), occlusion, fistula, aneurysm, and dissection. The MRA findings were then correlated with DSA. RESULTS: The sensitivity and specificity of MRA for detection of disease in the entire carotid and vertebrobasilar systems were 90% and 97%, respectively; for the carotid system alone, the sensitivity and specificity were 94% and 97%, respectively; and for the vertebrobasilar system they were 88% and 98% respectively. The overall interobserver reliability was 98% (kappa = 0.92). CONCLUSION: CE MRA is accurate at detecting disease not only in the carotid vessels, but also in the vertebrobasilar circulation, and has the potential to provide a comprehensive and noninvasive evaluation of the head and neck arteries in a single study.