Endovascular Mechanical Thrombectomy for Ischemic Stroke Treatment in the Setting of Aortic Dissection: Case Report.

Introduction: Acute ischemic stroke can occur in the setting of aortic dissection. Information concerning the utility of endovascular mechanical thrombectomy as an intervention for patients with aortic dissection who are experiencing an acute stroke due to large vessel occlusion is limited to a few case reports. Case series of patients presenting with this clinical situation are needed to further investigate the potential utility of this procedure when patients with acute ischemic stroke and aortic dissection are encountered. Case Presentation: We report a patient with a chronic Stanford type A aortic dissection with dissection extension into the left common carotid artery and left internal carotid artery who had a good clinical outcome following mechanical thrombectomy for a symptomatic middle cerebral artery occlusion. We also review other cases in which endovascular mechanical thrombectomy was conducted in patients with aortic dissection and acute ischemic stroke and discuss the potential risks and benefits of carotid artery stenting in this clinical situation. Conclusion: The rate of successful arterial recanalization in patients with aortic dissection, large vessel occlusion, and acute ischemic stroke treated with mechanical thrombectomy is high. The intervention has been associated with good neurological outcomes and a low rate of procedure-related complications. Additional case series are needed to help discern if our observations are present in a broader array of patients in order to identify which patients are most likely to benefit from mechanical thrombectomy.

Republished:Aspiration catheter failure leading to carotid-cavernous fistula during stroke thrombectomy.

Endovascular thrombectomy in acute ischaemic stroke commonly uses aspiration catheters, either alone or in combination with stent retrievers. The Penumbra Aspiration System (Penumbra, Alameda, California, USA) was first approved by the US Food and Drug Administration in 2007, with low reported device-related complications. We present a case of a previously unreported complication related to malfunction of a Penumbra aspiration catheter during stroke thrombectomy resulting in a carotid-cavernous fistula.

Aspiration catheter failure leading to carotid-cavernous fistula during stroke thrombectomy.

Endovascular thrombectomy in acute ischaemic stroke commonly uses aspiration catheters, either alone or in combination with stent retrievers. The Penumbra Aspiration System (Penumbra, Alameda, California, USA) was first approved by the US Food and Drug Administration in 2007, with low reported device-related complications. We present a case of a previously unreported complication related to malfunction of a Penumbra aspiration catheter during stroke thrombectomy resulting in a carotid-cavernous fistula.

Image-Guided Hypofractionated Proton Therapy in Early-Stage Non-Small Cell Lung Cancer: A Phase 2 Study.

PURPOSE: Due to the excellent outcomes with image-guided stereotactic body radiotherapy for patients with early-stage non-small cell lung cancer (NSCLC) and the low treatment-related toxicities using proton therapy (PT), we investigated treatment outcomes and toxicities when delivering hypofractionated PT. MATERIALS AND METHODS: Between 2009 and 2018, 22 patients with T1 to T2 N0M0 NSCLC (45% T1, 55% T2) received image-guided hypofractionated PT. The median age at diagnosis was 72 years (range, 58-90). Patients underwent 4-dimensional computed tomography simulation following fiducial marker placement, and daily image guidance was performed. Nine patients (41%) were treated with 48 GyRBE in 4 fractions for peripheral lesions, and 13 patients (59%) were treated with 60 GyRBE in 10 fractions for central lesions. Patients were assessed for CTCAEv4 toxicities with computed tomography imaging for tumor assessment. The primary endpoint was grade 3 to 5 toxicity at 1 year. RESULTS: The median follow-up for all patients was 3.5 years (range, 0.2-8.8 years). The overall survival rates at 3 and 5 years were 81% and 49%, respectively. Cause-specific survival rates at 3 and 5 years were 100% and 75%, respectively. The 3-year local, regional, and distant control rates were 86%, 85%, and 95%, respectively. Four patients experienced in-field recurrences between 18 and 45 months after treatment. One patient (5%) developed a late grade 3 bronchial stricture requiring hospitalization and stent. CONCLUSION: Image-guided hypofractionated PT for early-stage NSCLC provides promising local control and long-term survival with a low likelihood of toxicity. Regional nodal and distant relapses remain a problem.

Physical validation of UF-RIPSA: A rapid in-clinic peak skin dose mapping algorithm for fluoroscopically guided interventions.

PURPOSE: The purpose of this study was to experimentally validate UF-RIPSA, a rapid in-clinic peak skin dose mapping algorithm developed at the University of Florida using optically stimulated luminescent dosimeters (OSLDs) and tissue-equivalent phantoms. METHODS: The OSLDs used in this study were InLightTM Nanodot dosimeters by Landauer, Inc. The OSLDs were exposed to nine different beam qualities while either free-in-air or on the surface of a tissue equivalent phantom. The irradiation of the OSLDs was then modeled using Monte Carlo techniques to derive correction factors between free-in-air exposures and more complex irradiation geometries. A grid of OSLDs on the surface of a tissue equivalent phantom was irradiated with two fluoroscopic x ray fields generated by the Siemens Artis zee bi-plane fluoroscopic unit. The location of each OSLD within the grid was noted and its dose reading compared with UF-RIPSA results. RESULTS: With the use of Monte Carlo correction factors, the OSLD's response under complex irradiation geometries can be predicted from its free-in-air response. The predicted values had a percent error of -8.7% to +3.2% with a predicted value that was on average 5% below the measured value. Agreement within 9% was observed between the values of the OSLDs and RIPSA when irradiated directly on the phantom and within 14% when the beam first traverses the tabletop and pad. CONCLUSIONS: The UF-RIPSA only computes dose values to areas of irradiated skin determined to be directly within the x ray field since the algorithm is based upon ray tracing of the reported reference air kerma value, with subsequent corrections for air-to-tissue dose conversion, x ray backscatter, and table/pad attenuation. The UF-RIPSA algorithm thus does not include the dose contribution of scatter radiation from adjacent fields. Despite this limitation, UF-RIPSA is shown to be fairly robust when computing skin dose to patients undergoing fluoroscopically guided interventions.

Complicated Complication: How Interventional Radiologists Should Manage Acute Iatrogenic Cardiac Tamponade.

Computed tomography guided biopsies are common interventional procedures that are necessary for confirmation of imaging findings. Additionally, percutaneous biopsies are necessary for the elucidation of a patient's clinical findings with disease pathology. Though interventionists perform these procedures regularly without consequence, various complications may arise depending on the tissues biopsied. Examples of such complications may include hemorrhage, hematoma formation, or perforation of surrounding vessels. In the case of mediastinal biopsies, less common but higher-risk complications may include pneumothorax, perforation of arterial vessels, and damage to the cardiac tissues resulting in decompensation. Interventionists should understand the risks of performing these procedures and should be prepared to intervene if life-threatening complications arise. As interventional cardiologists are often prepared to manage decompensating cardiac complications, interventional radiologists must likewise anticipate the same to occur when conducting procedures that may affect cardiac tissues. The following case demonstrates a technique for correcting a complicated complication arising from a mediastinal biopsy, which resulted in a pericardial effusion and patient decompensation.

Hydro-marking Your Territory: Using a Novel Percutaneous Tagging System to Assist Pulmonary Nodule Identification During Video-assisted Thoracoscopic Surgery.

The management of lung cancer is highly dependent on surgical resection. There are different surgical managements that are utilized on a patient to patient basis. Small lung nodules are particularly difficult to resect and have a higher postoperative complication rate. Video-assisted thoracoscopic surgery is the preferred method of surgery over open thoracotomy, but requires the preoperative percutaneous placement of a marker to help the surgeon identify the nodule once conducting surgical resection. There are various methods to place percutaneous markers, but have reported complications. The following case will present the novel placement of a hydrogel tagging system on a small pulmonary nodule, demonstrating superiority to other methods of percutaneous marker placement.

A hybrid phantom system for patient skin and organ dosimetry in fluoroscopically guided interventions.

PURPOSE: The purpose of this study was to investigate calibrations for improved estimates of skin dose and to develop software for computing absorbed organ doses for fluoroscopically guided interventions (FGIs) with the use of radiation dose structured reports (RDSR) and the UF/NCI family of hybrid computational phantoms. METHODS AND MATERIALS: Institutional review board approval was obtained for this retrospective study in which ten RDSRs were selected for their high cumulative reference air kerma values. Skin doses were computed using the University of Florida's rapid in-clinic peak skin dose algorithm (or UF-RIPSA). Kerma-area product (KAP) meter calibrations and attenuation of the tabletop with pad were incorporated into the UF-RIPSA. To compute absorbed organ doses the RDSRs were coupled with software to develop Monte Carlo input decks for each irradiation event. The effects of spectrum matching were explored by modeling (a) a polychromatic x-ray energy beam made to match measured first half-value layers of aluminum, (b) an unmatched spectrum, (c) and a mono-energetic beam equivalent to the effective x-ray energy. The authors also considered the practicality of computing organ doses for each irradiation event within a RDSR. RESULTS: The KAP meter is highly dependent on the quality of the x-ray spectra. Monte Carlo based attenuation coefficients for configurations in which the beam is transmitted through the tabletop with pad reduced the amount by which the software overestimated skin doses. For absorbed organ dose computations, the average ratios of computed organ doses for a non-fitted to fitted spectrum and effective energy to fitted spectrum were 0.45 and 0.03, respectively. Monte Carlo simulations on average took 38 min per patient. All in-field organ tallies converged with a relative error of less than 1% and out-of-field organs tallies within 10% relative error. CONCLUSIONS: This work details changes to the UF-RIPSA software that include an expanded library of computational phantoms, attenuation coefficients for tabletop with pad, and calibration curves for the KAP meter. For the computation of absorbed organ dose, it is possible to model each irradiation event separately on a patient-dependent model that best morphometrically matches the patient, thus providing a full report of internal organ doses for FGI patients.

Preoperative Protective Endovascular Covered Stent Placement Followed by Surgery for Management of the Cervical Common and Internal Carotid Arteries with Tumor Encasement.

Objective The objective of this study was to report the outcomes on a preliminary cohort of patients with tumor encasement of either, or both, the cervical internal carotid artery (ICA) and common carotid artery (CCA) following preoperative covered stent placement and surgical resection. Setting This study was set at the University of Florida College of Medicine, Jacksonville, FL. Participants Subjects who received preoperative stenting of the cervical ICA/CCA before surgical resection of head and neck tumors between April 1, 2015, and July 31, 2015 were participated. Main Outcome Measures The outcomes assessed were resectability of tumors after stenting, histopathological assessment of specimen margins, complications associated with stenting. Results Five subjects received preoperative covered stent placement of the ICA/CCA before surgical resection. The mean age was 65.2 years. Median follow-up was 3.5 months. Excision of the adventitia from the stent was performed in all subjects. No intraoperative complications occurred. One vascular-related complication occurred in one subject who suffered occlusion of the stent, sustaining a ministroke. No involvement of tumor at the deep margin (inner surface of adventitia) of the resection was seen in any subjects. Conclusions Preoperative covered stent placement of the cervical ICA/CCA in the management of subjects with head and neck tumors who display encasement on preoperative imaging may represent a safe and effective treatment.

To nearly come full circle: Nonoperative management of high-grade IV-V blunt splenic trauma is safe using a protocol with routine angioembolization.

INTRODUCTION: Nonoperative management (NOM) of hemodynamically stable high-grade (IV-V) blunt splenic trauma remains controversial given the high failure rates (19%) that persist despite angioembolization (AE) protocols. The NOM protocol was modified in 2011 to include mandatory AE of all grade (IV-V) injuries without contrast blush (CB) along with selective AE of grade (I-V) with CB. The purpose of this study was to determine if this new AE (NAE) protocol significantly lowered the failure rates for grade (IV-V) injuries allowing for safe observation without surgery and if the exclusion of grade III injuries allowed for the prevention of unnecessary angiograms without affecting the overall failure rates. METHODS: The records of patients with blunt splenic trauma from January 2000 to October 2014 at a Level I trauma center were retrospectively reviewed. Patients were divided into two groups and failure of NOM (FNOM) rates compared: NAE protocol (2011-2014) with mandatory AE for all grade (IV-V) injuries without CB and selective AE for grade (I-V) with CB versus old AE (OAE) protocol (2000-2010) with selective AE for grade (I-V) with CB. RESULTS: Seven hundred twelve patients underwent NOM with 522 (73%) in the OAE group and 190 (27%) in the NAE group. Evolving from the OAE to the NAE strategy resulted in a significantly lower FNOM rate for the overall group (grade I-V) (OAE vs. NAE, 4% to 1%, p = 0.04) and the grade (IV-V) group (OAE vs. NAE, 19% vs. 3%, p = 0.01). Angiograms were avoided in 113 grade (I-III) injuries with no CB; these patients had NOM with observation alone and none failed. CONCLUSIONS: A protocol using mandatory AE of all high-grade (IV-V) injuries without CB and selective AE of grade (I-V) with CB may provide for optimum salvage with safe NOM of the high-grade injuries (IV-V) and limited unnecessary angiograms. LEVEL OF EVIDENCE: Therapeutic study, level IV.

At first blush: absence of computed tomography contrast extravasation in Grade IV or V adult blunt splenic trauma should not preclude angioembolization.

BACKGROUND: To clarify the role, indications, and outcomes for angioembolization (AE) of nonoperatively managed (NOM) splenic trauma, the implications of absent contrast blush (CB) on computed tomography of high-grade (IV-V) blunt splenic trauma (BST) in adults were analyzed. METHODS: All BST patients presenting at a single institution from July 2000 to December 2011 were retrospectively reviewed. Grade of injury (American Association for the Surgery of Trauma scale), CB on initial computed tomography, numbers of NOM and undergoing AE, and failures of NOM were analyzed. Statistical analysis was performed using χ(2). RESULTS: Of the 1,056 total BST patients, 556 (64%) were hemodynamically stable and eligible for NOM; 95 NOM patients (17%) had CB. AE was performed in 88 of these, with angiographic extravasation found in 86 (97.7%), and 3 of these 88 (3.4%) failed NOM. The remaining 7 CBs were observed without AE, of which 5 (71.4%) failed NOM (p = 0.0004). Of all 556 NOM patients, 51 (9.5%) had high-grade injuries without CB; 20 of these (39%) underwent AE, 17 (85.0%) underwent angiographic extravasation, and there were no NOM failures in this group. The other 31 high-grade injuries without CB or AE had 8 failures of NOM (26%) (p = 0.03). CONCLUSION: The strong correlation of CB with active bleeding on angiogram mandates AE for CB in all BST undergoing NOM. However, the absence of CB in high-grade (IV-V) BST does not reliably exclude active bleeding. This may be the reason for the high reported failure rates of NOM in high-grade (IV-V) BST because AE is not typically performed in the absence of CB. These data suggest that all hemodynamically stable high-grade (IV-V) BST in adults should undergo AE regardless of CB to optimize the success and safety of NOM. LEVEL OF EVIDENCE: Therapeutic study, level III.

Selective angiographic embolization of blunt splenic traumatic injuries in adults decreases failure rate of nonoperative management.

BACKGROUND: To determine whether angioembolization (AE) in hemodynamically stable adult patients with blunt splenic trauma (BST) at high risk for failure of nonoperative management (NOM) (contrast blush [CB] on computed tomography, high-grade IV-V injuries, or decreasing hemoglobin) results in lower failure rates than reported. METHODS: The records of patients with BST from July 2000 to December 2010 at a Level I trauma center were retrospectively reviewed using National Trauma Registry of the American College of Surgeons. Failure of NOM (FNOM) occurred if splenic surgery was required after attempted NOM. Logistic regression analysis was used to identify factors associated with FNOM. RESULTS: A total of 1,039 patients with BST were found. Pediatric patients (age <17 years), those who died in the emergency department, and those requiring immediate surgery for hemodynamic instability were excluded. Of the 539 (64% of all BST) hemodynamically stable patients who underwent NOM, 104 (19%) underwent AE and 435 (81%) were observed without AE (NO-AE). FNOM for the various groups were as follows: overall NOM (4%), NO-AE (4%), and AE (4%). There was no significant difference in FNOM for NO-AE versus AE for grades I to III: grade I (1% vs. 0%, p = 1), grade II (2% vs. 0%, p = 0.318), and grade III (5% vs. 0%, p = 0.562); however, a significant decrease in FNOM was noted with the addition of AE for grades IV to V: grade IV (23% vs. 3%, p = 0.04) and grade V (63% vs. 9%, p = 0.03). Statistically significant independent risk factors for FNOM were grade IV to V injuries and CB. CONCLUSION: Application of strictly defined selection criteria for NOM and AE in patients with BST resulted in one of the lowest overall FNOM rates (4%). Hemodynamically stable BST patients are candidates for NOM with selective AE for high-risk patients with grade IV to V injuries, CB on initial computed tomography, and/or decreasing hemoglobin levels. LEVEL OF EVIDENCE: III, therapeutic study.

Age does not affect outcomes of nonoperative management of blunt splenic trauma.

BACKGROUND: The purpose of this study was to examine the effect of age on the outcomes of nonoperative management (NOM) of blunt splenic trauma (BST). STUDY DESIGN: The records of patients with BST, from July 2000 to December 2010 at a level I trauma center, were retrospectively reviewed using NTRACS (National Trauma Registry of the American College of Surgeons). Patients were divided into 2 age groups: 17 to 55 years and greater than 55 years. Stepwise logistic regression analysis was used to identify risk factors associated with failure of nonoperative management (FNOM). RESULTS: There were 539 hemodynamically stable patients with BST who underwent NOM. Of these, 459 were age 55 or less, and 80 were greater than 55. Overall, there was no significant difference in FNOM rate for patients age 55 or less vs greater than 55 (4% vs 5%, p = 0.73). This also held true when FNOM was analyzed by each grade: I (1% vs 3%, p = 0.38), II (2% vs 0%, p = 1.0), III (4% vs 0%, p = 1.0), IV (8% vs 20%, p = 0.33), and V (21% vs 50%, p = 0.47). The addition of angioembolization (AE) to high grade IV to V injuries significantly lowered the FNOM rate: age 55 or less (6% AE vs 28% NO-AE, p = 0.02); with a trend toward significance for age greater than 55 (0% AE vs 60% NO-AE, p = 0.2). Age was not a statistically significant independent risk factor for FNOM (p = 0.37). CONCLUSIONS: Age does not affect outcomes of NOM of BST. High grade (IV to V) injuries are not a contraindication to NOM for patients older than 55. As experience with AE grows in patients with high grade injury and age greater than 55, it may prove to be a valuable adjunct to NOM in this group of patients.

Skin dose mapping for fluoroscopically guided interventions.

PURPOSE: To introduce a new skin dose mapping software system for interventional fluoroscopy dose assessment and to analyze the benefits and limitations of patient-phantom matching. METHODS: In this study, a new software system was developed for visualizing patient skin dose during interventional fluoroscopy procedures. The system works by translating the reference point air kerma to the location of the patient's skin, which is represented by a computational model. In order to orient the model with the x-ray source, geometric parameters found within the radiation dose structured report (RDSR) are used along with a limited number of in-clinic measurements. The output of the system is a visual indication of skin dose mapped onto an anthropomorphic model at a resolution of 5 mm. In order to determine if patient-dependent and patient-sculpted models increase accuracy, peak skin dose was calculated for each of 26 patient-specific models and compared with doses calculated using an elliptical stylized model, a reference hybrid model, a matched patient-dependent model and one patient-sculpted model. Results were analyzed in terms of a percent difference using the doses calculated using the patient-specific model as the true standard. RESULTS: Anthropometric matching, including the use of both patient-dependent and patient-sculpted phantoms, was shown most beneficial for left lateral and anterior-posterior projections. In these cases, the percent difference using a reference model was between 8 and 20%, using a patient-dependent model between 7 and 15%, and using a patient-sculpted model between 3 and 7%. Under the table tube configurations produced errors less than 5% in most situations due to the flattening affects of the table and pad, and the fact that table height is the main determination of source-to-skin distance for these configurations. In addition to these results, several skin dose maps were produced and a prototype display system was placed on the in-clinic monitor of an interventional fluoroscopy system. CONCLUSIONS: The skin dose mapping program developed in this work represents a new tool that, as the RDSR becomes available through automated export or real-time streaming, can provide the interventional physician information needed to modify behavior when clinically appropriate. The program is nonproprietary and transferable, and also functions independent to the software systems already installed on the control room workstation. The next step will be clinical implementation where the workflow will be optimized along with further analysis of real-time capabilities.

The influence of patient size on dose conversion coefficients: a hybrid phantom study for adult cardiac catheterization.

In this study, the influence of patient size on organ and effective dose conversion coefficients (DCCs) was investigated for a representative interventional fluoroscopic procedure-cardiac catheterization. The study was performed using hybrid phantoms representing an underweight, average and overweight American adult male. Reference body sizes were determined using the NHANES III database and parameterized based on standing height and total body mass. Organ and effective dose conversion coefficients were calculated for anterior-posterior, posterior-anterior, left anterior oblique and right anterior oblique projections using the Monte Carlo code MCNPX 2.5.0 with the metric dose area product being used as the normalization factor. Results show body size to have a clear influence on DCCs which increased noticeably when body size decreased. It was also shown that if patient size is neglected when choosing a DCC, the organ and effective dose will be underestimated to an underweight patient and will be overestimated to an underweight patient, with errors as large as 113% for certain projections. Results were further compared with those published for a KTMAN-2 Korean patient-specific tomographic phantom. The published DCCs aligned best with the hybrid phantom which most closely matched in overall body size. These results highlighted the need for and the advantages of phantom-patient matching, and it is recommended that hybrid phantoms be used to create a more diverse library of patient-dependent anthropomorphic phantoms for medical dose reconstruction.

Quantitative contrast enhanced magnetic resonance imaging for the evaluation of peripheral arterial disease: a comparative study versus standard digital angiography.

OBJECTIVE: The purpose of this study is to evaluate the accuracy of semiautomated analysis of contrast enhanced magnetic resonance angiography (MRA) in patients who have undergone standard angiographic evaluation for peripheral vascular disease (PVD). BACKGROUND: Magnetic resonance angiography is an important tool for evaluating PVD. Although this technique is both safe and noninvasive, the accuracy and reproducibility of quantitative measurements of disease severity using MRA in the clinical setting have not been fully investigated. METHODS: 43 lesions in 13 patients who underwent both MRA and digital subtraction angiography (DSA) of iliac and common femoral arteries within 6 months were analyzed using quantitative magnetic resonance angiography (QMRA) and quantitative vascular analysis (QVA). Analysis was repeated by a second operator and by the same operator in approximately 1 month time. RESULTS: QMRA underestimated percent diameter stenosis (%DS) compared to measurements made with QVA by 2.47%. Limits of agreement between the two methods were +/- 9.14%. Interobserver variability in measurements of %DS were +/- 12.58% for QMRA and +/- 10.04% for QVA. Intraobserver variability of %DS for QMRA was +/- 4.6% and for QVA was +/- 8.46%. CONCLUSIONS: QMRA displays a high level of agreement to QVA when used to determine stenosis severity in iliac and common femoral arteries. Similar levels of interobserver and intraobserver variability are present with each method. Overall, QMRA represents a useful method to quantify severity of PVD.

MR angiography of aortoiliac occlusive disease: a phase III study of the safety and effectiveness of the blood-pool contrast agent MS-325.

PURPOSE: To evaluate prospectively the safety and effectiveness of aortoiliac magnetic resonance (MR) angiography enhanced with MS-325 (gadofosveset trisodium) at a dose of 0.03 mmol/kg; effectiveness was defined as accuracy relative to the reference standard, conventional angiography. MATERIALS AND METHODS: Study was approved by institutional review boards of participating institutions, and required national approvals were obtained. Study protocol conformed to Good Clinical Practice guidelines, and informed patient consent was obtained. Patients with known or suspected peripheral vascular disease received 0.03 mmol/kg MS-325 for aortoiliac MR angiography. They were also examined with conventional angiography. MS-325-enhanced MR was evaluated for safety and effectiveness. Along with unenhanced two-dimensional time-of-flight MR angiography, it was compared with conventional angiography for presence of vascular stenosis. Student t tests were used to identify significant improvement in diagnostic sensitivity, specificity, and accuracy, as well as quantitative characterization of stenoses by three blinded readers. Correlations between readers of conventional angiograms were calculated and compared with MR results. RESULTS: In 174 patients, MS-325-enhanced MR angiography showed significant improvement (P < or = .001) in sensitivity, specificity, and accuracy for diagnosis of clinically significant (> or =50%) stenosis, compared with unenhanced MR. For all readers, areas under the receiver operating characteristic curve for both quantitative and qualitative measures of significant disease increased (P < .001) for MS-325-enhanced MR compared with time-of-flight MR. All readers also expressed higher confidence in diagnosis (P < .001) and found fewer images uninterpretable with MS-325 enhancement. All measures of interpretation accuracy approached corresponding measures of correlation between readers of conventional angiograms. Incidence of severe and serious adverse events with MS-325 was low. No patients were withdrawn from study due to adverse events or abnormalities in laboratory results. There were no clinically important trends in findings at hematology, blood chemistry, urinalysis, electrocardiography, or physical examination. CONCLUSION: MR angiography with MS-325 provides significant improvement in effectiveness over unenhanced MR (and minimal and transient side effects) at a dose of 0.03 mmol/kg and was safe and effective for MR evaluation of patients with aortoiliac occlusive disease.