Faculty Bibliography

BACKGROUND:The reported rate of incidental parathyroidectomy (IP) during thyroid surgery is between 5.2 and 21.6 %. Current literature reports wide discrepancy in incidence, risk factors, and outcomes. Thus study was designed to address definitively the topic of IP and identify associated risk factors and clinical outcomes with this multi-institutional study. METHODS:This retrospective cohort study included 1767 total thyroidectomies that occurred between 1995 and 2014 at two academic centers. Pathologic reports were reviewed for the presence of unintentionally removed parathyroid glands. Demographics, potential risk factors, and postoperative calcium levels were compared with matched control group. Logistic regression, t tests, and Chi squared tests were used when appropriate. RESULTS:IP occurred in 286 (16.2 %) of thyroidectomies. Risk factors for IP were: malignancy, neck dissection, and lymph node metastases (p = 0.005, <0.001, and <0.001). Fifty-three (19.2 %) of IPs were intrathyroidal. Those with IP were more likely to have postoperative biochemical (65.6 vs. 42.0 %; p < 0.001) and symptomatic (13.4 vs. 8.1 %; p = 0.044) hypocalcemia than controls. The number of parathyroids identified intraoperatively was inversely correlated with the number of parathyroid glands in the specimen (p < 0.001). CONCLUSIONS:Our findings indicate that malignancy, lymph node dissection, and metastatic nodal disease are risk factors for IP. Patients with IP were more likely to have postoperative biochemical and symptomatic hypocalcemia than controls, showing that there is a physiologic consequence to IP. Additionally, intraoperative surgeon identification of parathyroid glands results in a lower incidence of IP, highlighting the importance of awareness of parathyroid anatomy during thyroid surgery.

PURPOSE/OBJECTIVE:The great spatial and temporal resolution of positron emission tomography might provide the answer for patients with primary hyperparathyroidism (pHPT) and non-localized parathyroid glands. We performed a systematic review of the evidence regarding all investigated tracers. METHODS:A study was considered eligible when the following criteria were met: (1) adults ≥17 years old with non-familial pHPT, (2) evaluation of at least one PET isotope, and (3) post-surgical and pathological diagnosis as the gold standard. Performance was expressed in sensitivity and PPV. RESULTS:of 51 % (p = 0.01) for all 14 studies. Pooled PPV ranged from 91 to 100 % with a pooled estimate of 98 % (95 % CI 96-100 %). Of the other investigated tracers, 18-FCH seems the most promising with high diagnostic performance. CONCLUSIONS:The results of our meta-analysis show that 11C-MET PET has an overall good sensitivity and PPV and may be considered a reliable second-line imaging modality to enable minimally invasive parathyroidectomy. Our literature review suggests that 18F-FCH PET may produce even greater accuracy and should be further investigated using both low-dose CT and MRI for anatomical correlation.

BACKGROUND:Preoperative imaging in patients with primary hyperparathyroidism and a previous parathyroid operation is essential; however, performance of conventional imaging is poor in this subgroup. Magnetic resonance imaging appears to be a good alternative, though overall evidence remains scarce. We retrospectively investigated the performance of magnetic resonance imaging in patients with and without a previous parathyroid operation, with a separate comparison for dynamic gadolinium-enhanced magnetic resonance imaging. METHODS:All patients undergoing magnetic resonance imaging prior to parathyroidectomy for primary hyperparathyroidism (first time or recurrent) between January 2000 and August 2015 at a high-volume, tertiary care, referral center for endocrine operations were included. We compared the sensitivity and positive predictive value of magnetic resonance imaging with conventional ultrasound and sestamibi on a per-lesion level. RESULTS:A total of 3,450 patients underwent parathyroidectomy, of which 84 patients with recurrent (n = 10) or persistent (n = 74) disease and 41 patients with a primary operation were included. Magnetic resonance imaging had a sensitivity and positive predictive value of 79.9% and 84.7%, respectively, and performance was good in both patients with and without a previous parathyroid operation. Adding magnetic resonance imaging to the combination of ultrasound and sestamibi resulted in a significant increase in sensitivity from 75.2% to 91.5%. Dynamic magnetic resonance imaging produced excellent results in the reoperative group, with sensitivity and a positive predictive value of 90.1%. CONCLUSION:Technologic advances have enabled faster and more accurate magnetic resonance imaging protocols, making magnetic resonance imaging an excellent alternative modality without associated ionizing radiation. Our study shows that the sensitivity of multimodality imaging for parathyroid adenomas improved significantly with the use of conventional and dynamic magnetic resonance imaging, even in the case of recurrent or persistent disease.

BACKGROUND:The extent of thyroidectomy for low-risk well-differentiated thyroid cancer (WDTC) remains controversial. Historically, total thyroidectomy (TT) has been recommended for WDTC ≥1 cm in size. However, recent National Comprehensive Cancer Network and American Thyroid Association guidelines recognize unilateral thyroid lobectomy as a viable alternative for 1-4 cm cancers due to their otherwise favorable prognosis, with TT remaining the preferred option for tumors with unfavorable pathological characteristics. This study sought to determine how often a completion TT would be recommended based on these guidelines if lobectomy was initially performed in patients with 1-4 cm WDTC without preoperatively known risk factors. METHODS:Patients who underwent thyroidectomy for 1-4 cm WDTC (January 2000 to January 2010) were retrospectively reviewed. Patients with preoperatively known high-risk characteristics, including gross extrathyroidal extension (ETE) on preoperative imaging, clinically apparent lymph node metastases, distant metastases, history of radiation, and positive family history, were excluded. The pathology specimens from the cancer-containing lobe were evaluated for features that would lead to a recommendation for TT based on current guidelines, including aggressive histology, vascular invasion, microscopic ETE, positive margins, and any positive lymph nodes within the specimen. RESULTS:Of 1000 consecutive patients operated for WDTC, 287 would have been eligible for lobectomy as the initial operation. The mean age in this cohort was 45 years, and 80% were women. Aggressive tall-cell variant histology was found in one patient (0.5%), angio-invasion in 34 (12%), ETE in 48 (17%), positive margins in 51 (18%), and positive lymph nodes in 49 (18%) patients. Completion TT would have been recommended in 122/287 (43%) patients. Even in those with 1-2 cm cancers, completion TT would have been recommended in 52/143 (36%) patients. CONCLUSIONS:Nearly half of the patients with 1-4 cm WDTC who are eligible for lobectomy under current guidelines would require completion TT based on pathological characteristics of the initial lobe. Surgeons, endocrinologists, and patients need to balance the relative benefits, risks, and costs of initial TT versus the possible need for reoperative completion TT.

BACKGROUND:Incomplete surgical resection with gross positive tumor margin increases the risk of recurrence in patients with well-differentiated thyroid cancer (WDTC); however, it is not clear whether a microscopic positive margin found only on final pathology has similar implications on patient outcomes. METHODS:We conducted a single-institution retrospective review of all patients undergoing total thyroidectomy for T1-T2 WDTC (January 2000-January 2010). Factors that may influence the risk of locoregional recurrence or distant metastasis were evaluated by univariate and multivariate analysis. RESULTS:Of 1000 consecutive patients undergoing surgical resection for WDTC, 684 T1-T2 cancers were included. Mean age was 46 years and 81 % were women. Of this total cohort, 78 (11 %) patients had microscopic positive margins. Radioactive iodine (RAI) was administered in 47/78 (60 %) patients with positive margins versus 312/606 (51 %) patients without positive margins. After a mean follow-up of 46 months, 53 (8 %) patients developed recurrent disease (1 local and 52 nodal). On multivariate analysis, nodal metastases (N1, odds ratio [OR] 7.7) and contralateral multifocality (OR 3.7) were independent risk factors for recurrent disease. A microscopic positive margin was not a risk factor for recurrence. CONCLUSIONS:A microscopic positive margin found only on final pathological analysis does not increase the risk of recurrence in T1-T2 WDTC. Clinicians should interpret such pathology findings accordingly when considering further surveillance and treatment decisions such as the use of RAI ablation.

BACKGROUND: Adrenal venous sampling is an important lateralization study for primary aldosteronism, but inability to cannulate the right adrenal vein is not uncommon and interpreted as a failed study. We challenged this notion by examining whether data from incomplete left-sided adrenal venous sampling could accurately predict lateralization. METHODS: Sixty-two adrenal venous sampling studies from 2007 to 2014 at 2 tertiary-care institutions were reviewed. For this analysis, data from the right adrenal vein were excluded. The study variable was the aldosterone:cortisol ratio of the left adrenal vein compared with the inferior vena cava (LAV/IVC). Scatterplot analysis identified high and low LAV/IVC cutoffs that predicted accurately unilateral disease in 1 institutional cohort and validated in the second cohort. RESULTS: Thirty-six studies of adrenal venous sampling were evaluated at the first institution and divided into 3 diagnostic categories: unilateral-left (n = 14), unilateral-right (n = 12), and bilateral (n = 10). Cutoff values of the ratios of LAV/IVC of >/= 5.5 and