For single- gland disease, reported sensitivities and PPVs range from 92% to 94% [30,38] and 88% to 92% [38,39], respectively. For MGD, reported sensitivities and PPVs range from 43% to 67% [39,40] and 89% to 100%, respectively [32,39]. A data-driven rationale for the noncontrast CT phase has been provided (eg, differentiation of parathyroid from thyroid tissue): 22% of parathyroid lesions have an enhancement pattern similar to thyroid on arterial and venous phases and therefore may be missed if the noncontrast phase were excluded [30]. However, a few retrospective reports suggest that eliminating the noncontrast CT phase may not adversely affect test performance [41-43]. The largest retrospective study (278 patients) of CT neck with IV contrast (without the noncontrast phase) reports sensitivity of 55% and PPV of 57% among patients with single-gland disease, and sensitivity of 23% and PPV of 19% among patients with MGD [44]. Several studies have directly compared the performance of neck CT without and with IV contrast to ultrasound (US) and to nuclear medicine scans within the same patient population. Most of these studies found the performance of neck CT without and with IV contrast to be superior [29,31,38,40]; however, a prospective study of 91 patients found neck CT without and with IV contrast (58% sensitivity, 88% PPV) to be inferior to dual isotope (sestamibi and I-123) pinhole subtraction scintigraphy (93% sensitivity, 98% PPV) [45]. MRI Neck MRI neck is an emerging technique for PHPT preoperative localization and may be performed without IV contrast, with IV contrast, or without and with IV contrast. Most studies evaluating the performance of MRI neck for preoperative localization in the setting of PHPT are retrospective and include fewer than 50 patients. As the initial imaging study, the sensitivity of MRI neck without and with IV contrast performed at 1.5T has been reported to be between 64% and 79% [46-48].
Parathyroid Adenoma. For single- gland disease, reported sensitivities and PPVs range from 92% to 94% [30,38] and 88% to 92% [38,39], respectively. For MGD, reported sensitivities and PPVs range from 43% to 67% [39,40] and 89% to 100%, respectively [32,39]. A data-driven rationale for the noncontrast CT phase has been provided (eg, differentiation of parathyroid from thyroid tissue): 22% of parathyroid lesions have an enhancement pattern similar to thyroid on arterial and venous phases and therefore may be missed if the noncontrast phase were excluded [30]. However, a few retrospective reports suggest that eliminating the noncontrast CT phase may not adversely affect test performance [41-43]. The largest retrospective study (278 patients) of CT neck with IV contrast (without the noncontrast phase) reports sensitivity of 55% and PPV of 57% among patients with single-gland disease, and sensitivity of 23% and PPV of 19% among patients with MGD [44]. Several studies have directly compared the performance of neck CT without and with IV contrast to ultrasound (US) and to nuclear medicine scans within the same patient population. Most of these studies found the performance of neck CT without and with IV contrast to be superior [29,31,38,40]; however, a prospective study of 91 patients found neck CT without and with IV contrast (58% sensitivity, 88% PPV) to be inferior to dual isotope (sestamibi and I-123) pinhole subtraction scintigraphy (93% sensitivity, 98% PPV) [45]. MRI Neck MRI neck is an emerging technique for PHPT preoperative localization and may be performed without IV contrast, with IV contrast, or without and with IV contrast. Most studies evaluating the performance of MRI neck for preoperative localization in the setting of PHPT are retrospective and include fewer than 50 patients. As the initial imaging study, the sensitivity of MRI neck without and with IV contrast performed at 1.5T has been reported to be between 64% and 79% [46-48].