This study uses ROC analysis to compare scintimammography results with 99mTc.Sestamibi and 99mTc.Oxidronate as reported by 4 experienced nuclear medicine observers blind to the results of conventional triple assessment (TA) and the consensus score of 2 observers aware of TA results.
63 patients (124 breasts) attending a symptomatic clinic underwent both investigations within 5 days of each other. 10 minute planar lateral images (patient prone) followed by anterior (supine) images were acquired starting 5 minutes post injection of 740 MBq of each radiopharmaceutical. Observers scored each breast directly from the digital data using a 5 grade classification system; 1 = normal, 2 = probably normal/diffuse benign disease, 3 = equivocal, 4 = suspicious/probably malignant, 5 = highly probably malignant. Written guidance was provided together with a training set of example images for each of the classification scores.
Histological evidence of malignancy or benignity was obtained in 44 patients. Malignancy was otherwise excluded in the remaining patients either through negative investigations (scintimammography & TA results) or by follow-up of at least 6 months. Malignancy was present in 51% of patients (27% of breasts).
Both bivariate and area tests were used to determine the degree of statistical significance between ROC curves. No significant difference (p-values > 0.05) was demonstrated between observers for both radiopharmaceuticals. One observer demonstrated significantly improved reporting with Sestamibi as compared to Oxidronate; the remaining 3 observers approached a significant difference. However, there was no significant difference between radiopharmaceuticals for the consensus score. The Oxidronate ROC curve for the consensus score was significantly better than that for all 4 observers, whilst the Sestamibi ROC curves approach a significant difference. The pooled ROC curves created from the combined observer data demonstrated no significant difference as compared to consensus score ROCs for Sestamibi. However, the consensus Oxidronate ROC curve was significantly better than that from pooled data.
Blind reporting of Sestamibi scintimammography is superior to Oxidronate scintimammography in identifying breast malignancy. However, there is no significant difference between radiopharmaceuticals when reporting combines knowledge of TA results.
Mackie A, McCauley E, Cook AIM, Cadigan P, Bradford IMJ. Evaluation of 99mTc.Sestamibi versus 99mTc.Oxidronate Scintimammography by ROC Analysis. Poster presentation at the European Association of Nuclear Medicine Society, Paris, Sept. 2000 Eur J Nuc Med 2000; 27 (8) : PS_476.
Dr. Alison Mackie, Durham Unit, Durham. Tel: +44 (0)191-333-2219.
Regional Medical Physics Department, Newcastle General Hospital, Newcastle upon Tyne, NE4 6BE, UK.
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