Iodine-stained fragmented thromboembolism

Abstract

Aim Iodine-stained fragmented thromboembolism (ISFT) is a rare phenomenon encountered in the immediate aftermath of mechanical thrombectomy or rarely as a complication of post–carotid stenting. The aim was to describe the imaging appearance and discuss its pathophysiology. Method This is a retrospective review of patients who underwent mechanical thrombectomy for acute stroke at a single institution over the period of one year. All patients underwent the standard acute stroke imaging protocol (CT head, CT angiogram (CTA) and CT brain perfusion) and when clinically appropriate followed by catheter angiogram and mechanical thrombectomy. ISFT was defined as an arterial luminal filling defect with Hounsfield density equal to or greater than iodine seen on the biplanar CT or conventional CT. The presence and location of ISFT were documented. Standard CT angiogram (CTA) or magnetic resonance angiogram (MRA) was performed 24–48 hours after the neurointerventional procedure to assess for recanalization, volume of infarction and the fate of the ISFT. Results ISFTs were identified in eight (five males and three females, age range 18–80 years) out of 49 patients in the following locations: distal M1 ( n = 1), M2 ( n = 4), M3 ( n = 1), A1 ( n = 1), distal A2 ( n = 1). ISFT and vessel recanalization occurred in five patients on follow-up. ISFT and vessel occlusion persisted in two patients. Conclusion ISFT is likely the result of mechanical disruption of a thromboembolus, and porosity of the thromboembolus fragment may transiently retain iodinated contrast. Recognition of this entity may be important to aid detection of residual thromboembolism and avoid misinterpretation as calcified thromboembolism.

Connecting the DOTs: a novel imaging sign on flat-panel detector CT indicating distal vessel occlusions after thrombectomy

“…The presence of a punctiform hyperdense signal on immediate post-interventional FPDCT has been described previously. 12 In a small retrospective series (n=49), eight patients showed punctiform hyperdense signal increase on FPDCT performed immediately after EVT. The authors defined this as iodine-stained fragmented thromboembolism (ISFT), hypothesizing that the most likely explanation for their findings is a penetration of contrast into the distal thromboembolism that had occurred during the intervention, or represents stasis of residual contrast proximal to the thromboemboli.…”

“…The authors defined this as iodine-stained fragmented thromboembolism (ISFT), hypothesizing that the most likely explanation for their findings is a penetration of contrast into the distal thromboembolism that had occurred during the intervention, or represents stasis of residual contrast proximal to the thromboemboli. 12 In the present study, we have defined the DOT sign as a punctiform or tubular hyperdense signal in the course of an intracranial artery in the target territory. We also found the DOT sign to be frequent, being present in half of the entire cohort.…”

“…11 Recently, a case series suggested focal vascular hyperdensities on flat-panel detector CT (FPDCT) as an imaging correlate of remaining distal vessel occlusions after EVT. 12 Contrast staining of fragmented thrombi or contrast stagnation proximal to the clot have been proposed as pathophysiological explanations. 12 A systematic evaluation of this imaging finding, however, was never performed.…”

“…12 Contrast staining of fragmented thrombi or contrast stagnation proximal to the clot have been proposed as pathophysiological explanations. 12 A systematic evaluation of this imaging finding, however, was never performed. We aimed to assess the prevalence of focal vascular hyperdensities, together with its association to baseline characteristics and reperfusion success.…”

“…The most likely reasons for the difference in prevalence between these two studies seem to be: study design (retrospective cohort vs case series), reading process (independent core lab vs two neuroradiologists), study period with improved imaging quality on new generation angiography systems (2022 vs 2016), FPDCT slice thickness (1 vs 3 mm), and operational definitions of the post-interventional FPDCT findings (DOT sign: punctiform or tubular hyperdense signal increase in the course of an intracranial artery within the initial EVT target territory vs ISFT: luminal filling defect with greater Hounsfield density compared with the contralateral side). 12 The exact pathophysiological explanation for the DOT sign remains unclear and needs to be investigated in further studies. Both contrast stagnation proximal to the occlusion and penetration of contrast material into the thrombus need to be considered.…”