Abstract
ObjectivesAccurate pre-operative imaging of parathyroid adenomas (PAs) is essential for successful minimally invasive surgery; however, rates of non-localizing PAs can be as high as 18 %. Multiphasic dual-energy CT (DECT) has the potential to increase accuracy of PA detection by enabling creation of paired material maps and spectral tissue characterization. This study prospectively evaluated the utility of 3-phase DECT for PA identification in patients with failed localizatio n via standard imaging.MethodsPatients with primary hyperparathyroidism and non-localizing PAs underwent a 3 phase post-contrast DECT scan acquired at 25, 55, and 85 s. The scans were prospectively evaluated by two head and neck radiologists. Pre-operative localization was compared to intraoperative localization and final histopathology. A post-hoc DECT spectral density characterization was performed on pathologically-proven PAs.ResultsOut of 29 patients with primary hyperparathyroidism and non-localized PAs, DECT identified candidates in 26. Of the 23 patients who underwent parathyroidectomy, DECT provided precise anatomic localization in 20 patients (PPV = 87.0 %), one with multi-gland disease. The virtual unenhanced images were not found to be useful for diagnosis but successful diagnosis was made without an unenhanced phase regardless. Spectral analysis demonstrated a distinct spectral Hounsfield attenuation curve for PAs compared to lymph nodes on arterial phase images.Conclusion3-phase DECT without an unenhanced phase is a feasible salvage imaging modality for previously non-localizing parathyroid adenomas. Optimal interpretation is achieved based on a combination of perfusion characteristics and other morphologic features. Advanced spectral DECT analysis has the potential for further increasing accuracy of PA identification in the future.
Highlights
Accurate pre-operative localization of parathyroid adenomas (PAs) is essential for successful minimally invasive surgery
We prospectively evaluated the utility of multiphasic dual-energy CT (DECT) for PA localization in a group of patients having discordant or unidentified PAs on a workup consisting at a minimum of ultrasound and sestamibi
The most common presenting complaint was asymptomatic incidental hypercalcemia with elevated parathyroid hormone, but presentations ranged from osteopenia to renal failure (Table 1)
Summary
Accurate pre-operative localization of parathyroid adenomas (PAs) is essential for successful minimally invasive surgery. The addition of SPECT or SPECT/CT may further increase sensitivity for PAs to approximately 90 % or more according to some studies [2, 4], but that has not been the experience in our institution. PAs have more rapid and greater arterial phase enhancement and a more rapid rate of contrast wash-out compared to the normal thyroid gland [5]. Lymph nodes are typically hypoenhancing compared to PAs on arterial phase images, but demonstrate slow progressive enhancement on more delayed images, a pattern different from typical PAs [5]. One of the concerns about 4D-CT is radiation exposure because of multiple acquisitions To this end, there are reports demonstrating that not all of the phases described in the original 4D-CT protocol may be necessary for accurate PA localization [11, 12]. Whereas one approach is to eliminate one or more phases from conventional multiphasic CT, another approach is to use more advanced techniques such as dual-energy CT for increasing the diagnostic yield and potentially reducing the number of acquisition needed for a diagnostic exam
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
