Contrast-enhanced MR Angiography of Peripheral Arteries including Pedal Vessels at 1.0 T: Feasibility Study with Dedicated Peripheral Angiography Coil

Time-resolved dual-station calf-foot three-dimensional bolus chase MR angiography with fluoroscopic tracking

PURPOSE

To refine, adapt, and evaluate the technical aspects of fluoroscopic tracking for generating dual-station high-spatial-resolution MR angiograms of the calves and feet using a single injection of contrast material.

MATERIALS AND METHODS

Nine subjects (seven healthy volunteers followed by two patients) were imaged using a two-station calf-foot three-dimensional time-resolved bolus chase MR angiography protocol which provided <1.0 mm(3) spatial resolution throughout and 2.5- and 6.6-s frame times at the calf and foot stations, respectively. Real-time reconstruction of calf station time frames allowed visually guided triggering of table advance to the foot station. The studies were independently read and scored by two radiologists in six image quality categories.

RESULTS

On average, overall diagnostic quality at the calf and foot stations was good-to-excellent, the calf arteries and all but the smallest foot arteries had good-to-excellent signal and sharpness, artifact and venous contamination were minor, and signal continuity across the inter-station interface was good.

CONCLUSION

The feasibility of fluoroscopic tracking has been demonstrated as an efficient approach for high spatiotemporal imaging of the arteries of the calves and feet with good-to-excellent diagnostic quality and low degrading venous contamination.

Contrast-enhanced magnetic resonance angiography following subintimal recanalization

PURPOSE

To describe the appearance of lower extremity runoff vessels following subintimal recanalization (SIR) on contrast-enhanced magnetic resonance angiography (ceMRA) and compare 2 different ceMRA techniques.

METHODS

A total of 6 patients underwent stepping table 3-dimensional (3D) ceMRA and time-resolved 2-dimensional (2D) MRA within 1 to 3 days (mean 1.83 days) following SIR. The 2 techniques were compared with intra-arterial digital subtraction angiography (DSA).

RESULTS

A total of 15 arteries were recanalized in 6 patients. Three-dimensional ceMRA allowed evaluation of patency in all segments above the knee. Postprocedural hyperemia impaired the assessment of the trifurcation vessels on 3D ceMRA. Due to its higher temporal resolution 2D MRA was not affected by venous contamination and allowed reliable confirmation of patency of the recanalized vessels.

CONCLUSIONS

Diagnostic MRA studies of the lower extremity runoff vessels following SIR is possible, but a hybrid technique using a stepping table MR DSA and a time-resolved sequence like 2D MRA of the calf station is necessary for runoff assessment.

Value of MDCT angiography in developing treatment strategies for critical limb ischemia

OBJECTIVE

The purpose of this study was to assess the value of MDCT angiography in the development of strategies for the treatment of patients with critical limb ischemia.

MATERIALS AND METHODS

During a 12-month period, 150 patients were referred to our department for CT angiography of the peripheral arteries. All patients (n = 28) with clinical stage IV peripheral arterial occlusive disease were included in this retrospective study. The treatment reports, discharge summaries, and follow-up examinations were reviewed to ascertain the number of patients correctly treated on the basis of the CT angiographic findings.

RESULTS

After CT angiography, endovascular treatment was indicated for eight patients, surgical revascularization for four patients, and a combined endovascular and surgical approach for two patients. That the correct treatment decision had been made in all 14 cases was confirmed on the basis of successful endovascular or surgical revascularization. In eight patients, medical treatment was indicated, and one patient underwent amputation at the level of the thigh. Five patients were referred for complementary digital subtraction angiography, but no additional findings were made. During follow-up, three of the original 28 patients were in grave general condition and died within 7 weeks after CT angiography. Thirteen patients needed no additional treatment during the follow-up period through January 2008. After a median treatment-free interval of 381 days, 12 patients underwent additional revascularization because of clinical progression of disease.

CONCLUSION

MDCT angiographic findings lead to accurate recommendations for the management of critical limb ischemia. Thus CT angiography seems to be an important technique for the management of stage IV peripheral arterial occlusive disease in patients without absolute contraindications to CT angiography.

Intra-arterial MR-angiography on an open-bore MR-scanner compared to digital-subtraction angiography of the infra-popliteal runoff in patients with peripheral arterial occlusive disease

PURPOSE

To evaluate the diagnostic value of contrast-enhanced intra-arterial 3D-MR-angiography (IA-MRA) of the infra-popliteal arteries in an open-bore magnet. Number, severity of arterial lesions, and artefacts were compared to routinely performed intra-arterial digital-subtraction angiography (IA-DSA) in patients suffering from symptomatic peripheral arterial occlusive disease (PAOD).

MATERIAL AND METHODS

Fifteen patients admitted for PAOD underwent percutaneous transluminal angioplasty (PTA) by IA-DSA. After PTA, IA-MRA of the infra-popliteal station was performed on an open-bore 1.5T MR-scanner applying a low dose intra-arterial contrast-enhanced 3D-gradient-echo-MRA with gadopentate dimeglumine. The reading was performed by three blinded readers distinguishing moderate (< or =50%), significant stenoses (51-99%) and vessel occlusions. Imaging artefacts were recorded and binary classified as not disturbing or compromising the observation of the arterial tree.

RESULTS

Overall IA-DSA revealed 36 moderate stenoses (< or =50%), 38 significant stenoses (51-99%), and 10 vessel occlusions. For the detection of significant stenoses and occlusions, the overall sensitivity, specificity, positive predictive value, negative predictive value and accuracy of IA-MRA were 96%, 83%, 88%, 94% and 90%. The only observed artefact was venous overlay in four stations. The readout was not hampered in any case.

CONCLUSION

Intra-arterial contrast-enhanced 3D-gradient-echo-MRA on an open-bore MR-scanner offers an acceptable diagnostic accuracy in diagnosing peripheral arterial occlusive disease in the infra-popliteal region and correlates well with DSA.

Effect of MDCT angiographic findings on the management of intermittent claudication

OBJECTIVE

The purpose of this study was to assess the reliability of treatment decisions based on MDCT angiographic findings of stage IIb peripheral arterial occlusive disease (PAOD).

MATERIALS AND METHODS

Fifty-eight patients with stage IIb PAOD underwent CT angiography of the abdominal aorta and runoff vessels for further treatment planning. Treatment reports, discharge summaries, and follow-up examinations were reviewed to determine the number of treatments correctly planned on the basis of CT angiographic findings.

RESULTS

On the basis of CT angiographic findings, endovascular treatment was indicated for 18 patients, surgical revascularization for nine patients, and a combined endovascular and surgical approach for two patients. Conservative treatment was indicated for 29 patients. On the basis of successful revascularization, the correctness of the treatment decision was confirmed in all but one patient (n = 28). The treatment plan was modified for one patient referred for surgical revascularization. In that patient, stenosis of the common femoral artery had been overlooked on CT angiography. Patients for whom conservative management was indicated on the basis of CT angiographic findings (n = 29) had a mean follow-up period of 501 days without needing revascularization treatment. This result was defined as indirect confirmation of the accuracy of the decision made with CT angiography.

CONCLUSION

The findings on MDCT angiography led to correct treatment recommendations for patients with claudication. Thus, CT angiography should be used in the management of PAOD.

16-MDCT Angiography of Aortoiliac and Lower Extremity Arteries: Comparison with Digital Subtraction Angiography

OBJECTIVE

The objective of our study was to prospectively compare CT angiography (CTA) performed on a 16-MDCT scanner and digital subtraction angiography (DSA) in patients with peripheral arterial disease.

SUBJECTS AND METHODS

CTA and DSA were compared in 50 patients. CTA was independently evaluated by two blinded observers. DSA was evaluated by two additional blinded observers in consensus. Consensus DSA served as the reference standard for comparisons with CTA in terms of diagnostic quality, grading of stenoocclusive lesions, visualization of collaterals, impact on patient management, and time required for analysis.

RESULTS

No significant differences in diagnostic quality were observed between CTA and DSA above the ankle; both CTA observers noted significantly better visualization of pedal arteries (70 and 72 segments, respectively) than on DSA (57 segments). Of 958 stenoocclusive lesions on DSA, CTA observers 1 and 2 detected 933 and 929 lesions, respectively. Sensitivity and specificity for the detection of hemodynamically relevant (> 50%) lesions was 93.3% and 96.5% for observer 1 and 90.1% and 95.6% for observer 2. Collaterals were seen at 150 arterial levels on DSA compared with 97 and 92 levels on CTA (p < 0.05, both observers). Patient management decisions based on CTA were equivalent to those based on DSA in 49 of the 50 patients.

CONCLUSION

CTA is an effective noninvasive alternative to DSA for the evaluation of peripheral arterial disease.

Magnetic Resonance Angiography in Infrapopliteal Arterial Disease

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.

Establishing a Cardiac Imaging Service

The tremendous progress in the field of cardiac imaging has drawn the interest of many radiologists, but has left them uncertain as to how obtain the training necessary to become expert practitioners. This review addresses the challenges in establishing a cardiac imaging service including equipment issues, training and credentialing issues, as well as referrals and reimbursement.

Gadobenate dimeglumine-enhanced MR angiography: Diagnostic performance of four doses for detection and grading of carotid, renal, and aorto-iliac stenoses compared to digital subtraction angiography

PURPOSE

To determine the diagnostic performance of contrast-enhanced MR angiography (CE-MRA) with four doses of gadobenate dimeglumine for detection of significant steno-occlusive disease of the carotid, renal, and pelvic vasculature.

MATERIALS AND METHODS

Eighty-four patients with suspected disease of the renal (n = 16), pelvic (n = 41), or carotid (n = 27) arteries underwent CE-MRA (3D-spoiled gradient-echo sequences) at 1.5T. CE-MRA was performed with gadobenate dimeglumine at 0.025, 0.05, 0.1, or 0.2 mmol/kg (23, 24, 19, and 18 patients, respectively) administered at 2 mL/sec. Accuracy, sensitivity, specificity, and positive and negative predictive values (PPV and NPV, respectively) for detection of significant disease (>50% stenosis or occlusion for renal/pelvic arteries; >70% stenosis or occlusion for carotid arteries) was determined by three fully blinded, independent radiologists using conventional digital subtraction angiography (DSA) as reference standard. All comparisons were tested statistically (ANOVA, chi-square, and Mantel-Haenszel tests as appropriate) and reader agreement (kappa) was assessed.

RESULTS

Values for accuracy, sensitivity, specificity, PPV, and NPV on CE-MRA were consistently higher for 0.1 mmol/kg gadobenate dimeglumine (accuracy = 95.2-97.3%, sensitivity = 84.2% (all readers), specificity = 96.9-99.2%, PPV = 80.0-94.1%, NPV = 97.6-97.7%). The greater accuracy of the 0.1 mmol/kg dose was significant (P < 0.01, all readers) compared to all other dose groups. Agreement between the three readers was good for all dose groups (kappa >/=0.58), with the highest percent agreement (85.7%) noted for the 0.1 mmol/kg dose.

CONCLUSION

Significantly better diagnostic performance on CE-MRA of the renal, pelvic, and carotid arteries is achieved with a gadobenate dimeglumine dose of 0.1 mmol/kg bodyweight.

Peripheral arteries in diabetic patients: standard bolus-chase and time-resolved MR angiography

PURPOSE

To prospectively determine the diagnostic performance of a combination of standard bolus-chase magnetic resonance (MR) angiography and MR angiography with time-resolved imaging of contrast kinetics (TRICKS) for depicting severity of peripheral vascular disease of the lower extremity, including the pedal arteries, in diabetic patients with digital subtraction angiography (DSA) as the reference standard.

MATERIALS AND METHODS

An ethical committee approved this study; written informed consent was obtained from patients. Standard three-station and TRICKS MR angiography of the calf and foot were performed in 31 consecutive diabetic patients (23 men, eight women; mean age, 67 years; range, 43-81 years). Two readers separately assessed images of arterial segments as diagnostic or nondiagnostic and graded stenosis. Results were compared with those at DSA when the corresponding arterial segments were considered diagnostic at DSA. Wilcoxon signed rank test was used to determine if a significant difference between imaging techniques existed, and kappa statistics were used to determine interobserver agreement.

RESULTS

The difference between standard MR angiography and DSA regarding the number of diagnostic segments in the thigh was not significant (P = .50). A significantly higher number of calf and foot segments was considered diagnostic at TRICKS MR angiography than at standard MR angiography (P < .025). Sixteen of 26 segments in the foot that were considered nondiagnostic at DSA were considered diagnostic at TRICKS MR angiography. Average sensitivity of standard MR angiography for depicting hemodynamically significant arterial stenosis was 84% (reader 1) and 83% (reader 2) in the thigh and 78% (reader 1) and 80% (reader 2) in the calf. For both readers, average specificity was 97% in the thigh and 90% in the calf. Sensitivity and specificity of TRICKS MR angiography in the calf and foot were improved compared with those at standard MR angiography.

CONCLUSION

TRICKS MR angiography of the distal calf and pedal vessels is superior to standard MR angiography regarding the number of diagnostic segments and assessment of the degree of luminal narrowing.

Diagnostic Accuracy of Multislice CT Angiography in Peripheral Arterial Disease

A systematic search of the PubMed and Medline databases of English literature was performed to determine the diagnostic accuracy of multislice computed tomographic (CT; MSCT) angiography in peripheral arterial disease (PAD) compared with digital subtraction angiography (DSA). Studies comparing MSCT angiography with DSA in peripheral vascular disease were included, and the diagnostic value of MSCT angiography in terms of sensitivity, specificity, and diagnostic accuracy was compared and analyzed. Ten studies (19 comparisons) met the criteria and were included for analysis. The pooled sensitivity, specificity, and accuracy rates were 92%, 91%, and 91%, respectively, at all arterial levels; 92%, 94%, and 93%, respectively, at aortoiliac arteries; 96%, 85%, and 92%, respectively, at femoropopliteal arteries; and 91%, 85%, and 87%, respectively, at infrapopliteal arteries. A significant difference was found in the sensitivity of MSCT angiography in PAD between four-slice CT and 16-slice CT, between aortoiliac and femoropopliteal arterial segments, and between femoropopliteal and infrapopliteal arterial segments (P<.05). This review demonstrates that MSCT angiography has a high diagnostic value and could be a reliable alternative to DSA in the diagnosis of PAD.

Magnetic Resonance Angiography of the Peripheral Vessels in Patients with Peripheral Arterial Occlusive Disease: When Is an Additional Conventional Angiography Required?

The purpose of this work was to find out how often the clinician asks for a conventional angiography (CA) in patients with peripheral arterial occlusive disease (PAOD) after a magnetic resonance angiography (MRA) has been performed and how often the CA reveals additional information for therapy planning. Quality criteria for the MRA were defined and tested to see whether they can predict the need for an additional CA. In this prospective study, 81 patients suffering from PAOD (Fontaine classification IIa, n = 13; IIb, n = 33; III, n = 10; IV, n = 25) were examined with a 1.5-T MR-scanner with dedicated coils using a step-by-step technique. The vascular surgeon decided whether he could plan the therapy on the basis of the MRA or if he needed an additional CA. The MRA was assessed in terms of the image quality of the MRA and regarding therapeutic management of the patient in a two-grade scale: sufficient and insufficient. In 27/81 (33%) patients, the clinician asked for a CA, which revealed new information in only 11 patients. The relative number of MRAs with insufficient image quality was significantly higher (p < 0.01) in the group with additional information on CA (8/11) compared to the group without additional information (0/16). The assessment of an MRA based on image quality and regarding therapeutic management of the patient might reduce the number of CAs for therapy planning in patients with PAOD.