Contrast-Enhanced Magnetic Resonance Imaging Based T1-Mapping And Extracellular Volume Fractions Are Associated With Peripheral Artery Disease

Background Extracellular volume fraction (ECV), measured with contrast-enhanced magnetic resonance imaging (CE-MRI), has been utilized to study myocardial fibrosis but its role in peripheral artery disease (PAD) remains unknown. We hypothesized that T1-mapping and ECV differ between PAD patients and matched-controls. Methods and Results A total of 37 individuals (18 PAD, 19 controls) underwent 3.0T CE-MRI at the mid-calf. T1-mapping was done before and after gadolinium contrast with a motion corrected Modified Look Locker Inversion Recovery (MOLLI) pulse sequence. T1 values were calculated with a 3-parameter Levenberg-Marquardt curve fitting algorithm. T1-maps were quantified in 5 calf muscle compartments (anterior [AM], lateral [LM], and deep posterior [DM] muscle groups; soleus [SM], and gastrocnemius [GM] muscles). Averaged peak blood pool T1 values were obtained from the posterior (PT) and anterior tibialis (AT); and peroneal artery (PE). PAD ECV was calculated for each muscle group. T1 values and ECV are heterogeneous across calf muscle compartments. Native peak T1 values of the AM, LM, and DM were significantly higher in PAD patients compared to controls (all p<0.028). ECV of the AM and SM were significantly higher in PAD patients compared to controls (AM: 26.4% (21.2, 31.6) vs. 17.3% (10.2, 25.1), p=0.046; SM: 22.7% (19.5, 27.8) vs. 13.8% (10.2, 19.1), p=0.020). Conclusions Native peak T1 values and ECV fractions of several calf muscle compartments are higher in PAD patients compared with matched-controls. These data suggest a potential utility of ECV to noninvasively determine skeletal muscle fibrosis in PAD. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This work was supported by funding from the National Institutes of Health (R01HL137763 and K25HL121149 both to GB) and the American Heart Association (13BGIA16720014 to GB). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Study participants provided informed consent, and the study obtained approval from the institutional review boards at the Houston Methodist Hospital and the Michael E. DeBakey Veterans Affairs Medical Center, Houston, TX. Ethical approval was given. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes The data supporting the findings of this study are available from the corresponding author upon reasonable request.