Validation of MRI assessment of foot perfusion for improving treatment of patients with peripheral artery disease.

INTRODUCTION: Information on tissue perfusion in the foot is important when treating patients with chronic limb-threatening ischemia. This study aims to test the reliability of different magnetic resonance sequences when measuring perfusion in the foot. METHODS: Sixteen healthy volunteers had their right foot scanned in a test/retest study with six different magnetic resonance sequences (BOLD, multi-echo gradient echo (mGRE), 2D and 3D pCASL, PASL FAIR, and DWI with intravoxel incoherent motion (IVIM) with quantitative measurements of perfusion. For five sequences, cuff-induced ischemia followed by a hyperactive response was measured. Images of the feet were segmented into angiosomes and perfusion data were extracted from the five angiosomes. RESULTS: BOLD, PASL FAIR, mGRE, and DWI with IVIM had low mean differences between the first and second scans, while the results of 2D and 3D pCASL had the highest differences. Based on a paired t-test, BOLD, and FAIR were able to distinguish between perfusion and no perfusion in all angiosomes with p-values below 0.01. This was not the case with 2D and 3D pCASL with p-values above 0.05 in all angiosomes. The mGRE could not distinguish between perfusion and no perfusion in the lateral side of the foot. CONCLUSION: BOLD, mGRE, pASL FAIR, and DWI with IVIM seem to give more robust results compared to 2D and 3D pCASL. Further studies on patients with peripheral artery disease should explore if the sequences can have clinical relevance when assessing tissue ischemia and results of revascularization. IMPLICATIONS FOR PRACTICE: This study provides knowledge that could be used to improve the diagnosis of patient with chronic limb-threatening ischemia to explore tissue perfusion.

Incident reporting and level of MR safety education: A Danish national study.

INTRODUCTION: MR-safety remains a concern among MR professionals. We aimed to evaluate the extent of MR-related incidents using a national database and a questionnaire among MR professionals and to identify possible predictors for MR-related incidents. METHODS: MR-related incidents reported to a national database from 2015 to 2017 were scrutinized. A national online survey focussing on MR safety and education was performed. Quantitative analyses, descriptive statistics and regression analyses were used. RESULTS: The database included 196, 97 and 100 direct MR-related incidents in 2015, 2016 and 2017, respectively. Regarding the questionnaire, 208 MR professionals responded. Within the last year, 33% had been involved in an MR-related incident that was reported in the national database. At some time in their working life, 53% had been involved in an MR-related incident that was reported, but 25% had been involved in an incident that was not reported. The responses to the questionnaire reflected far more incidents than those reported to the database for all categories. Sixty-one percent of respondents indicated that external personnel in the MR environment are a safety risk. External personnel in the MR environment were found to be a predictor for reported and unreported MR-related incidents with odds ratio (OR) = 2.07; p = 0.033 and OR = 5.17; p = 0.0005 respectively. CONCLUSION: There seems to be severe underreporting of MR-related incidents. External personnel in the MR-environment and scanning patients in anaesthesia were found to be predictors for both reported and unreported MR-related incidents. Regulations regarding the minimum required MR safety education of different groups of MR professionals and external personnel are recommended. IMPLICATIONS FOR PRACTICE: Enforcing MR safety education and highlighting the importance of MR safety within hospital organisations would contribute to better patient and personnel safety.

A MRI-compatible stereotaxic localizer box enables high-precision stereotaxic procedures in pigs.

We present a nonmagnetic Plexiglas stereotaxic localizer box that can be fitted directly to the pig skull by aluminum screws, allowing stereotaxic MRI or ventriculography and subsequent high-precision stereotaxic procedures. The localizer box was used to target the subthalamic nucleus (STN) bilaterally in five female Göttingen minipigs. Stereotaxic markers were inserted in the pig skull, the head fixated in the localizer box by aluminum screws inserted bilaterally in the zygoma bone with the hard palate locked on a horizontal palate holder. MRI was obtained on a 3T-MR-imager revealing the relation between the inserted markers and the estimated STN-position, and thus the target coordinates. After the MRI, a stereotaxic frame with attached micromanipulator was locked on to the localizer box converting it into a stereotaxic device. The stereotaxic markers were exposed and used as starting point for the stereotaxic procedure, whereby a microelectrode for electrolytic lesioning was inserted in the STN. Postmortem histological analysis revealed 70% correct STN-targeting. The average distance from the lesion center to the STN center was 1.2 mm with a S.D. of 1.1 mm. The most displaced lesion being 3.6 mm from the STN center. We conclude that the described localizer box secure firm head fixation, allowing stereotaxic MRI and subsequent conversion into a stereotaxic device for high-precision stereotaxic procedures.