Computed Tomographic Distinction of Intimal and Medial Calcification in the Intracranial Internal Carotid Artery

Abstract

BackgroundIntracranial internal carotid artery (iICA) calcification is associated with stroke and is often seen as a proxy of atherosclerosis of the intima. However, it was recently shown that these calcifications are predominantly located in the tunica media and internal elastic lamina (medial calcification). Intimal and medial calcifications are thought to have a different pathogenesis and clinical consequences and can only be distinguished through ex vivo histological analysis. Therefore, our aim was to develop CT scoring method to distinguish intimal and medial iICA calcification in vivo.MethodsFirst, in both iICAs of 16 cerebral autopsy patients the intimal and/or medial calcification area was histologically assessed (142 slides). Brain CT images of these patients were matched to the corresponding histological slides to develop a CT score that determines intimal or medial calcification dominance. Second, performance of the CT score was assessed in these 16 patients. Third, reproducibility was tested in a separate cohort.ResultsFirst, CT features of the score were circularity (absent, dot(s), <90°, 90–270° or 270–360°), thickness (absent, ≥1.5mm, or <1.5mm), and morphology (indistinguishable, irregular/patchy or continuous). A high sum of features represented medial and a lower sum intimal calcifications. Second, in the 16 patients the concordance between the CT score and the dominant calcification type was reasonable. Third, the score showed good reproducibility (kappa: 0.72 proportion of agreement: 0.82) between the categories intimal, medial or absent/indistinguishable.ConclusionsThe developed CT score shows good reproducibility and can differentiate reasonably well between intimal and medial calcification dominance in the iICA, allowing for further (epidemiological) studies on iICA calcification.

Risk factors for atherosclerotic and medial arterial calcification of the intracranial internal carotid artery

“…For all patients, the presence, morphologic characteristics and severity of iICA calcifications were scored on the thin slice CT data by one of three readers with at least 2 years of experience reading CT images. (PdJ, JdV, RK) The agreement between the readers was previously found to be good, with kappa's ranging from 0.70 to 0.80 [13]. The readers were blinded to the clinical data.…”

“…Based on the total score (range 0e11 points) the calcifications were defined as dominantly intimal (score <7 points), dominantly medial (score 7 points), indistinguishable (continuity of calcification unclassifiable, due to the presence of only very small amounts of calcification), or absent ( Fig. 1) [13]. Furthermore the severity of the calcifications was scored in a four-tier system (none, mild, moderate, severe) as previously described by Woodcock and colleagues [15].…”

“…However, these studies did not take the different localizations of calcification in the vascular wall into account. Based on a comparison with histopathology, we recently described a computed tomography (CT) scoring system that can determine the dominant calcification type in the iICA [13]. This scoring system allows us to evaluate the effect of risk factors on the different dominant calcification types.…”

Clipping treatment of posterior communicating artery aneurysms associated with arteriosclerosis and calcification: A single center study of 136�cases

“…One method that may be used to treat intracranial small aneurysms is with simple surgical clipping, as, due to the sufficient operative field, the middle cerebral artery and anterior communicating artery aneurysms may be clipped with little difficulty (4). In addition to the size and location of the aneurysms, the outcome is also associated with the extent of arteriosclerosis and calcification of the parent artery and aneurysm neck (5,6). When aneurysms occur in hardened and calcified arteries, aneurysm clipping is difficult, particularly in cases of aneurysms of the posterior communicating artery (PCoA), due to their low position and wide neck (6,7).…”

“…In addition to the size and location of the aneurysms, the outcome is also associated with the extent of arteriosclerosis and calcification of the parent artery and aneurysm neck (5,6). When aneurysms occur in hardened and calcified arteries, aneurysm clipping is difficult, particularly in cases of aneurysms of the posterior communicating artery (PCoA), due to their low position and wide neck (6,7). The hard, calcified aneurysm neck frequently may not allow for complete closure of the clip blades, which may therefore require the use of the aneurysm clip compression technique (8).…”