Results
Baseline demographics and treatment plans for the 29 patients with sickle cell CNS vasculopathy prior to implementation of the MRA scanning protocol in May 2016 are listed in Table 1. Indications for chronic transfusion therapy included primary stroke prevention for 7 patients, secondary stroke prevention for 17 patients, and chronic pain for 2 patients.
MRAs were performed for routine screening, symptoms including headache, or focal neurologic findings. Pre- May 2016, 16/29 patient studies used TE <5msec whereas post May 2016, 26/29 patient studies used TE <5msec.
For 12 of the 29 patients (41%), some or all stenosis that was previously seen on pre- May 2016 MRA imaging was not identified on MRA imaging done post- May 2016. Figures 2 and 3 show examples of MRAs in two patients in whom vasculopathy was no longer visualized. In six patients, there was a decrease in the classification of CNS vasculopathy, however, their treatment was not impacted. These patients were not on disease modifying therapy, already had significant stenosis requiring transfusions, or had undergone curative bone marrow transplant.
In six patients (21%) there was complete resolution of previously seen CNS vasculopathy that lead to a change in treatment plan; all six patients were on chronic transfusion therapy for primary stroke prevention and after review of newer imaging showing no vasculopathy, this therapy was discontinued. Two patients had an increase in the degree of classification of stenosis, suggestive of the commonly seen progression of sickle cell CNS vasculopathy, without change in their treatment plan.
As seen in Figure 4, 24 patients (83%) were on chronic transfusion therapy prior to May 2016, while this number decreased to 18 (62%) after May 2016. For the McNemar analysis (Table 2), clinical treatment plans were categorized as “Transfusions” or “Not transfusions” both pre- and post- implementation of the scanning protocol. 18 patients remained in the same category of requiring transfusion therapy pre- and post- implementation. While six patients on chronic transfusion therapy were able to discontinue transfusion therapy, 0 patients required escalation in treatment plan (starting chronic transfusion therapy). Five patients with CNS vasculopathy remained off chronic transfusion therapy. The proportion of patients with change in treatment plan after the implementation of scanning protocol with TE < 5msec was found to be statistically significant (p = 0.0412).