Manisha Bahl MD, MPH, Presenter: Nothing to Disclose

Ali R. Sepahdari MD, Abstract Co-Author: Nothing to Disclose

Julie A. Sosa MD, Abstract Co-Author: Nothing to Disclose

Jenny K. Hoang MBBS, Abstract Co-Author: Nothing to Disclose

Prior to performing minimally-invasive parathyroidectomy, preoperative imaging is required to localize parathyroid adenomas with a high degree of confidence. Several signs on 4DCT can be used to determine degree of confidence. The purpose of this study is to evaluate the performance of a confidence grading system for parathyroid lesions on 4DCT.

We retrospectively reviewed preoperative 4DCT scans in 63 consecutive patients from November 2012 to December 2013 with pathologically-proven parathyroid adenomas or hyperplasia. Two radiologists reviewed the CT images to localize parathyroid lesions. Lesions detected on imaging and confirmed by surgery were categorized by a three-category confidence grading system based on four enhancement patterns (Types A-D) and three secondary signs. “Consistent with” was defined as Type A/B enhancement with >/=1 secondary findings. “Suspicious” was Type A/B enhancement without secondary findings or Type C/D enhancement with >/=1 secondary findings. “Possible” was Type C/D enhancement without secondary findings. The enhancement patterns required the lesion to be lower in attenuation than the thyroid gland on the noncontrast phase but differed on the arterial and delayed phases. Secondary findings were size >/=1 cm, a cystic component, and the polar vessel sign. We calculated and compared the prevalence and positive predictive values (PPV) of each grading system category.

63 patients had 75 lesions. 54 patients had single adenomas and nine patients had multigland disease with 21 lesions. The sensitivities for single gland and multigland disease were 94% and 52%, respectively. 74 lesions (including four false positives) could be categorized by the grading system. “Consistent with” was seen in 51% of lesions and had 100% PPV. “Suspicious” represented 37% of lesions and had 96% PPV. Finally, “possible” represented 11% of lesions and had the lowest PPV (73%).

A grading system allows radiologists to communicate the degree of confidence when a lesion is detected on 4DCT, which is valuable for preoperative planning. The proposed system performs as intended in that the highest confidence grade has the highest PPV and the lowest grade has the lowest PPV.

A 4DCT grading system can communicate degree of confidence for parathyroid adenomas, and detection of a lesion with the highest confidence grade may reduce the need for further imaging.

Bahl, M, Sepahdari, A, Sosa, J, Hoang, J, Parathyroid Adenomas and Hyperplasia on 4DCT: Grading System for Degree of Confidence.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14008382.html