Susceptibility Etching on MRI in Patients with Microangiopathy

We detected a novel imaging sign, which consists of a specific imaging pattern of diffuse susceptibility effect, delineating the cortical-subcortical junction on high-resolution susceptibility-weighted images (SWIs). We describe magnetic resonance imaging findings in 10 patients with "susceptibility etching" and possible association with their abnormal coagulation profile.

A retrospective case series study with a search for cases that demonstrated susceptibility effect at the cortical-subcortical junction on SWI sequences was performed. The patients' respective coagulation profiles including prothrombin time, partial thromboplastin time, fibrinogen, D-dimer values, and platelet counts were reviewed. In addition, clinical history and neurological deficits were recorded.

We identified 10 patients with the "susceptibility etching" pattern at the cortical-subcortical junction. All patients were acutely ill and had a significantly elevated D-dimer (4,309 mcg/L to >10,000 mcg/L) with variably reduced platelet count. Two patients had reduced fibrinogen and 5 patients had prolonged international normalized ratio. Of the 10 patients, 4 died during hospitalization, within a few days of imaging. Pathology of 1 patient at autopsy demonstrated findings suggestive of a microvascular thrombotic or embolic event without overt parenchymal microhemorrhage.

In this preliminary case series, we describe patients with "susceptibility etching" on SWI who were also found to have profound coagulation impairment. While other comorbities may also contribute to this novel sign, we suggest that a possible etiology may be secondary to microvascular in situ formation of fine thrombi and/or emboli lodged into an area of vascular caliber reduction and maybe related to thrombotic microangiopathy.