Parathyroid Computed Tomography

4D SPECT/CT: A Hybrid Approach to Primary Hyperparathyroidism

Our rationale was to review the imaging options for patients with primary hyperparathyroidism and to advocate for judicious use of 4-dimensional (4D) SPECT/CT to visualize diseased parathyroid glands in patients with complex medical profiles or in whom other imaging modalities fail. We review the advantages and disadvantages of traditional imaging modalities used in preoperative assessment of patients with primary hyperparathyroidism: ultrasound, SPECT, and 4D CT. We describe a scheme for optimizing and individualizing preoperative imaging of patients with hyperfunctioning parathyroid glands using traditional modalities in tandem with 4D SPECT/CT. Using the input from radiologists, endocrinologists, and surgeons, we apply patient criteria such as large body habitus, concomitant multiglandular disease, multinodular thyroid disease, confusing previous imaging, and unsuccessful previous surgery to create an imaging paradigm that uses 4D SPECT/CT yet is cost-effective, accurate, and limits extraneous radiation exposure. 4D SPECT/CT capitalizes on the strengths of SPECT and 4D CT and addresses limitations that exist when these modalities are used in isolation. In select patients with complicated clinical parameters, preoperative imaging with 4D SPECT/CT can improve accuracy yet remain cost-effective.

Opportunistic Parathyroid Gland Assessment on Routine CT Could Decrease Morbidity from Undiagnosed Primary Hyperparathyroidism

RATIONALE AND OBJECTIVES

Gaps in primary hyperparathyroidism diagnosis are well-documented. End-organ damage correlates with disease duration and often occurs before diagnosis. We hypothesize that opportunistic parathyroid gland assessment on routine CT could decrease existing diagnosis gaps. Our purpose is to assess for enlarged parathyroid glands on contrast-enhanced CT acquired prior to biochemical screening and subsequent development of related morbidity.

MATERIALS AND METHODS

This retrospective study included consecutive patients with primary hyperparathyroidism undergoing parathyroidectomy with contrast-enhanced CT including the lower neck and upper chest acquired prior to biochemical screening. One neuroradiologist retrospectively evaluated all CTs for enlarged (estimated weight greater than 60 mg) parathyroid glands. Gold standard operative and pathology reports were correlated with CT findings, and medical records were reviewed for development of primary hyperparathyroidism-related comorbidities.

RESULTS

The sample comprised 38 patients (30 women, 8 men, median age 60 years) with 70 CTs of interest. The neuroradiologist identified 32 putative enlarged parathyroid glands (median estimated weight 307 mg) in 29 (76%) patients on CTs predating biochemical screening by a median of 30 months. Putative enlarged parathyroid glands on CT corresponded to pathologically proven parathyroid lesions in 26 (90%) patients. Of 26 patients with retrospectively identified pathologically proven parathyroid lesions, 12 (46%) developed at least 1 renal, bone, or neurocognitive comorbidity between CT and subsequent biochemical screening.

CONCLUSION

Enlarged parathyroid glands are frequently visible on routine CTs acquired years prior to primary hyperparathyroidism diagnosis. Biochemical screening based on enlarged glands could potentially prevent associated morbidity in almost half of such patients.