Controversy exists concerning the advantages and appropriateness of current imaging modalities of the localization of parathyroid tumors. We conducted a prospective, blinded study to compare the efficacy of 3 different imaging modalities in 40 patients with primary hyperparathyroidism (HPT). Patients with HPT were examined preoperatively by computer‐assisted thallium‐201/technetium‐99m scintigraphy (TTS), high‐resolution (GE 9800) computed tomography (CT), and high‐resolution (7.5 MHz) real‐time sonography (US). Each study was performed and interpreted independently. These patients then had a neck exploration and parathyroidectomy which allowed for clinical correlation of pathologic findings with the imaging results. Overall sensitivities of the 3 imaging modalities were TTS‐72%, CT‐72%, and US‐57%, with specificities of TTS‐93%, CT‐92%, and US‐96%. For lesions located below the thyroid (thymic tongue and mediastinum), sensitivities were TTS‐86%, CT‐29%, and US‐20%, all with specificities of 100%. In those HPT patients presenting with prior failed neck explorations, parathyroid tumors were detected with sensitivities of TTS‐88%, CT‐57%, and US‐67%, with specificities of 100%, 71%, and 100%, respectively. TTS with subsequent CT appears to be an optimal imaging strategy for HPT patients with prior failed neck explorations or suspected lesions below the thyroid. Since surgeons experienced in parathyroid surgery have a cure rate of 93% or greater in HPT patients without prior neck exploration, these imaging modalities may not be cost‐effective and thus not indicated for these patients.

Twenty-two patients with primary hyperparathyroidism underwent high-resolution magnetic resonance (MR) imaging with local (surface) coils for preoperative localization of enlarged parathyroid glands. The MR studies were interpreted prospectively and the results compared with findings at surgery and the results of computed tomography (CT), ultrasonography (US), and thallium-technetium scintigraphy (TTS). The sensitivity and specificity of MR imaging were .74 and .88, respectively. The sensitivity/specificity for the other modalities were as follows: 74/.95 for CT, .59/.82 for US, and .82/.98 for TTS. Enlarged parathyroid glands displayed a medium-intensity signal on T1-weighted images and a marked increase in intensity on T2-weighted images, but the degree of increase varied considerably.

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