In 12 patients after mechanical thrombectomy, 54 ASPECTS regions ultimately developed infarction; 40/54 (74.1%) showed hyperattenuation on PCCT iodine maps, but only 15/40 (37.5%) were visually hyperattenuating on conventional brain-window images. Thus, iodine accumulation was frequently measurable before becoming visually apparent on routine grayscale CT.
PCCT iodine-map attenuation very accurately predicted conventional brain-window visibility (AUC 0.997). An internally derived threshold of 8.33 HU provided 100% sensitivity and 96% specificity; patient-level bootstrap analysis yielded a median cutoff of 11.69 HU with a 95% interval of 8.33–12.67 HU.
The relative brain-window attenuation increase also performed well (AUC 0.984; threshold 3.06%), but showed substantially greater cutoff variability. The practical implication is that direct iodine quantification may provide a more robust and reproducible marker of post-thrombectomy contrast staining than visual assessment alone, although the thresholds remain pilot estimates requiring external validation.
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Figure 1. Examples of IM hyperattenuating areas that are clearly hyperattenuating on BW images (a,b), only mildly hyperattenuating on BW images (c,d), or not clearly hyperattenuating on BW images (e,f).
Protocol
Detail | Value |
|---|
Scanner | NAEOTOM Alpha.Peak |
Scan area | Brain |
Reconstructions | Brain window, iodine map, virtual non-contrast |
Follow-up imaging | Non-contrast CT approximately 24 h after PCCT |
Reference for infarction extent | Follow-up CT using ASPECTS |
Hemorrhage assessment | Virtual non-contrast images |
ROI analysis | Three circular 10 mm² ROIs per affected ASPECTS region |
Reference ROI | Matching contralateral region at the same axial level |
Quantitative metric | Iodine-map attenuation and relative brain-window attenuation increase (%ΔHU) |
Threshold analysis | ROC analysis with patient-level clustered bootstrap resampling, 2000 iterations |
Key Results
Parameter | Main finding |
|---|
Study population | 12 patients, 54 ASPECTS regions with final infarction |
Iodine-map positive regions | 40/54 (74.1%) |
Visible on brain-window images | 15/40 (37.5%) |
Iodine-map threshold | 8.33 HU; AUC 0.997, sensitivity 100%, specificity 96.0% |
Relative BW threshold | 3.06%; AUC 0.984, sensitivity 100%, specificity 92.0% |
Inter-reader agreement | κ 0.81 for iodine maps; κ 0.86 for brain-window visibility |
Source:
Pali M-C, Mangesius S, Eisenschink CE, Deisl P, Neumann L, Knoflach M, Pechlaner R, Glodny B, Lenhart L, Gizewski ER, Grams AE. From Iodine Maps to Brain Window Images: Quantitative Visibility Thresholds of Iodine Staining Using Photon-Counting CT—A Retrospective Observational Study. Diagnostics. 2026;16(18):2915. doi:10.3390/diagnostics16182915.
