Different spectral hounsfield unit curve and high-energy virtual monochromatic image characteristics of squamous cell carcinoma compared with nonossified thyroid cartilage.
OBJECTIVE
The attenuation of normal nonossified thyroid cartilage can be similar to that of head and neck squamous cell carcinoma on CT. We compared dual-energy CT spectral Hounsfield unit attenuation characteristics of nonossified thyroid cartilage with that of squamous cell carcinoma to determine the optimal virtual monochromatic image reconstruction energy levels for distinguishing tumor from normal nonossified thyroid cartilage.


METHODS
Dual-energy CT scans from 30 patients with histopathology-proved squamous cell carcinoma at different primary sites (laryngeal and nonlaryngeal) and 10 healthy patients were evaluated. Patients were scanned with a 64-section single-source scanner with fast-kilovolt (peak) switching, and scans were reconstructed at different virtual monochromatic energy levels ranging from 40 to 140 keV. Spectral attenuation curves of tumor and nonossified thyroid cartilage were quantitatively evaluated and compared. Any part of the tumor invading the cartilage, when present, was excluded from ROI analysis to avoid cross-contamination from areas where there could be a mixture of cartilage and invading tumor.


RESULTS
Normal nonossified thyroid cartilage had a characteristic, predictable spectral attenuation curve that was different from that of tumors. The greatest difference in attenuation of nonossified cartilage compared with tumor was on virtual monochromatic images of ≥95 keV (P < .0001), with sharp contrast between the relatively high attenuation of nonossified cartilage compared with that of tumor.


CONCLUSIONS
Head and neck squamous cell carcinoma has significantly different attenuation on virtual monochromatic images of ≥95 keV, compared with nonossified thyroid cartilage.
From the Department of Radiology (R.F., M.L., S.L.), Jewish General Hospital, McGill University, Montreal, Quebec, Canada rforghani@jg.mcgill.ca.
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Forghani
From the Department of Radiology (R.F., M.L., S.L.), Jewish General Hospital, McGill University, Montreal, Quebec, Canada.
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Levental
Department of Radiology (R.G.), Massachusetts General Hospital.
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Gupta
From the Department of Radiology (R.F., M.L., S.L.), Jewish General Hospital, McGill University, Montreal, Quebec, Canada.
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Lam
Department of Radiology (N.D., H.D.C.), Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts.
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Dadfar
Department of Radiology (N.D., H.D.C.), Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts.
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Curtin
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002294:Carcinoma, Squamous Cell / Q000473:pathology*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D007822:Laryngeal Neoplasms / Q000473:pathology; D008297:Male; D008875:Middle Aged; D010039:Otorhinolaryngologic Neoplasms / Q000473:pathology*; D012680:Sensitivity and Specificity; D012984:Software; D013957:Thyroid Cartilage / Q000473:pathology*; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014584:User-Computer Interface