Percentage arterial enhancement on 2D CT in the diagnosis of primary hyperparathyroidism: A prospective validation study and potential pitfalls.

BACKGROUND: Parathyroid lesions are identified by subjective enhancement and washout patterns on computed tomography (CT). We have previously proposed "percentage arterial enhancement" (PAE) as an objective index and now aim to validate its performance prospectively. METHODS: Dual-phase CT was performed in 40 consecutive primary hyperparathyroidism patients. PAE was calculated as [{arterial phase Hounsfield unit (HU)-unenhanced phase HU}/unenhanced phase HU] × 100. PAE > 128.9% was considered parathyroid. RESULTS: PAE had 94.2% sensitivity, 100% positive predictive value (PPV) in lateralization, and sensitivity and PPV of 93.9% in quadrant localization of single-gland disease. PAE failed to identify two lesions: an intrathyroidal parathyroid carcinoma in the background of multinodular goiter and another lower enhancing cystic parathyroid adenoma. PAE had 60% sensitivity, and 100% PPV to identify multigland disease. The mean effective dose was 2.74 mSV. CONCLUSIONS: PAE is a specific CT index for parathyroid lesions with less radiation exposure. Areas of caution include intrathyroidal and cystic lesions.

Preoperative prediction of parathyroid carcinoma in an Asian Indian cohort.

BACKGROUND: Parathyroid carcinoma (PC) requires preoperative prediction for appropriate surgical management. Differentiation from symptomatic primary hyperparathyroidism (sPHPT) cohort is difficult. METHODS: Patients with sPHPT from a tertiary-care center, Western India, including Cohort-A (n = 19 [10/M; 9/F]) with PC and Cohort-B (n = 93 [33/M; 60/F] with benign parathyroid lesions) were compared to derive predictors for differential diagnosis. RESULTS: There were no differences in clinical or biochemical parameters between the two cohorts. Comparison of CECT parameters showed that irregular shape, tumor heterogeneity, infiltration, short/long-axis ratio >0.76, and long-diameter >30 mm had high negative-predictive value and intratumoral calcification had 100% positive-predictive value to diagnose PC; whereas there were no differences in contrast-enhancement patterns. Long diameter, short/long-axis ratio, and heterogeneity were significant predictors on multivariate analysis. CONCLUSION: It is difficult to predict diagnosis of PC in an Indian sPHPT cohort based on clinical and biochemical parameters, whereas CECT parathyroid-based parameters can aid in diagnosis.

Tumor induced osteomalacia in head and neck region: single center experience and systematic review.

Tumor-induced osteomalacia in the head and neck region remains a challenging diagnosis to manage. Literature pertaining to management and outcome details remains sparse. We describe two cohorts: cohort 1 included seven patients from a single center in Western India with tumors located in paranasal sinuses (n = 3), intracranial (n = 2) and maxilla (n = 2). The unique features from our series is the management of persistent disease with radiation therapy (n = 2) and peptide receptor radionuclide therapy (PRRT) (n = 1). Cohort two has 163 patients identified from 109 publications for systematic review. Paranasal sinuses, mandible, intracranial disease, maxilla and oral cavity, in descending order, are reportedly common tumor sites. Within this cohort, mean age was 46 ± 14 years at presentation with 44.1% having local symptoms. Duration of symptoms varied from 1 to 240 months. Pre-surgery mean serum phosphorus was 1.4 ± 0.4 mg/dL and median FGF-23 levels were 3.6 (IQR:1.8-6.8) times of normal upper limit of normal. Majority (97.5%) were managed primarily with surgical excision; however, primary radiotherapy (n = 2) and surgery combined with radiotherapy (n = 2) were also reported. Twenty patients had persistent disease while nine patients had recurrence, more commonly noted with intracranial and oral cavity tumors. Surgery was the most common second mode of treatment employed succeeded by radiotherapy. Four patients had metastatic disease. The most common histopathological diagnosis reported is PMT mixed connective tissue, while the newer terminology 'PMT mixed epithelial and connective tissue type' has been described in 15 patients.

Percentage arterial enhancement: An objective index for accurate identification of parathyroid adenoma/hyperplasia in primary hyperparathyroidism.

BACKGROUND: Radiation exposure to neck by four-dimensional computerized tomography (4DCT) is relatively high and limits its use as a first-line investigation in evaluation of primary hyperparathyroidism (PHPT). Radiation exposure can be reduced by restricting the number of CT phases. Our aim was to study the performance of 4DCT in cohort of surgery-naïve PHPT patients, and to evaluate percentage enhancement as an objective radiological index to discriminate parathyroid lesions (adenoma/hyperplasia) from thyroid tissue and lymph nodes. MATERIALS AND METHOD: Retrospective study of 49 PHPT patients {(44 single-gland diseases (SGD) and five multiple-gland disease (MGD)} who underwent 4DCT (unenhanced, early arterial, early venous and delayed venous phase) pre-operatively. Two radiologists who were blinded to surgical location of parathyroid lesions examined the scans. Attenuation values were recorded for parathyroid lesions (n=50), thyroid gland (n=50) and lymph nodes (n=12) in different phases. Percentage enhancement for different phases was calculated as "(HU in a specific enhanced phase-HU in unenhanced phase)/HU in unenhanced phase" ×100. RESULTS: Inter-rater reliability between the two radiologists was 0.83 (Cohen's kappa). In SGD, sensitivity and PPV were 93.18% and 98.8% for lateralization, and 89.77% and 95.18% for quadrant localization, respectively. In MGD, 4DCT showed 50% sensitivity and 100% PPV. Percentage arterial enhancement showed highest area under curve (AUC=0.992) for differentiation of parathyroid lesions from thyroid tissue and lymph nodes. A cut-off value of 128.9% showed 95.8% sensitivity and 100% specificity for the identification of parathyroid lesions. CONCLUSIONS: We propose that percentage arterial enhancement can be used as an objective radiological index for accurate identification of parathyroid adenoma/hyperplasia.