Mortality among patients undergoing dipyridamole 99mTc Sestamibi SPECT: impact of blunted heart rate response and abnormal scans

Background Blunted heart rate response (BHRR) caused by cardiac neuropathy associated with dipyridamole stress, has been linked to cardiovascular (CV) outcome events. Whether BHRR is necessarily associated with abnormal perfusion is unknown. The aim of the study was to assess the incremental prognostic value of BHRR in a single center population undergoing Dipyridamole 99mTc Sestamibi SPECT test (DSPECT) for predicting late CV events. Methods 388 patients (aged 73±10 years, 45% females, 51% with known coronary disease) that underwent DSPECT over 3 years period were included. Abnormal DSPECT and BHRR were evaluated in relation to late death. Results Mean follow up period was 1560±565 (15–2431) days. During follow up period, 90 patients died. Mode of death was CV in 20 and non-CV in 70. BHRR (<20% heart rate increase), abnormal DSPECT, post-stress LVEF <60% and reversible defects were observed in 63%, 41%, 23% and 20% of patients, respectively. BHRR (HR -2.41, p<0.0006) and abnormal DSPECT (HR-1.62, p=0.02) were predictors of all-cause death. BHRR had incremental prognostic value over abnormal DSPECT (Figure, p<0.0005). Multivariable analysis identified age, dyspnea, insulin treated diabetes mellitus and dialysis as independent predictors of death while DSPECT and BHRR did not. However, BHRR remained a significant predictor of CV death [HR 8.1 (1.06, 62.0), p<0.05]. Conclusions In this contemporary DSPECT cohort, BHRR and DSPECT failed to predict all-cause mortality. However, BHRR was an independent predictor of CV death. FUNDunding Acknowledgement Type of funding sources: None. BHRR stratifies abnormal DSPECT

Diagnostic value of simultaneous 99mTc-sestamibi/123I-BMIPP imaging parameters for predicting the improvement of left ventricular wall motion after acute myocardial infarction using CZT SPECT system

Background Although the presence of 99mTc-sestamibi/123I-BMIPP-mismatch, the reverse redistribution (RR) of 99mTc-sestamibi and RR of 123I-BMIPP in patients with acute myocardial infarction (AMI) are known to significant markers for predicting the improvement of LV wall motion in the infarcted territory in chronic phase, few studies were performed to analyze them by simultaneous dual-isotope imaging using cadmium-zinc-telluride (CZT) SPECT system. Purpose The purpose of this study was to evaluate whether the presence of 99mTc-sestamibi/123I-BMIPP-mismatch or RR of 99mTc-sestamibi, RR of 123I-BMIPP make better prediction of the improvement of LV wall motion in the infarcted territory. Methods We evaluated 42 consecutive patients with AMI who had undergone both dual-isotope SPECT in acute phase and stress myocardial SPECT using 99mTc-tracers in chronic phase by Discovery NM530c. The presence of 99mTc-sestamibi/123I-BMIPP-mismatch, RR of 99mTc-sestamibi and RR of 123I-BMIPP were determined using traditional definition. The improvement of LV wall motion in the infarcted territory from acute phase to chronic phase was assessed using QGS. Results Of 42 patients, the improvement of LV wall motion in the infarcted territory from acute phase to chronic phase was found in 29 patients. The presence of 99mTc-sestamibi/123I-BMIPP-mismatch and RR of 99mTc-sestamibi and RR of 123I-BMIPP were significantly linked to predict the improvement of LV wall motion (p=0.0001, p=0.0001 and p=0.002, respectively). To predict the improvement of LV wall motion in the infarcted territory in chronic phase, the presence of 99mTc-sestamibi/123I-BMIPP-mismatch showed sensitivity of 93%, specificity of 85% and accuracy of 91%, while RR of 99mTc-sestamibi and RR of 123I-BMIPP had sensitivities of 72%, 48%, specificities of 85%, 100% and accuracies of 76%, 64%, respectively. The multivariate discriminant analysis revealed that the combination of 99mTc-sestamibi/123I-BMIPP-mismatch, RR of 99mTc-sestamibi and RR of 123I-BMIPP best predicted the improvement of LV wall motion in the infarcted territory in chronic phase with sensitivity of 93%, specificity of 85% and accuracy of 91% (chi-square=40.6), compared with RR of 99mTc-sestamibi and RR of 123I-BMIPP only (sensitivity 79%, specificity 85% and accuracy of 81%, chi-square=16.9). Conclusions The addition of 99mTc-sestamibi/123I-BMIPP-mismatch on RR of 99mTc-sestamibi and RR of 123I-BMIPP in patients with AMI, help better predict the improvement of LV wall motion in the infarcted territory in chronic phase. FUNDunding Acknowledgement Type of funding sources: None.

The Evaluation of Left Ventricle Ischemic Extent in Patients with Significantly Suspicious Cardiovascular Disease by 99mTc-Sestamibi Dynamic SPECT/CT and Myocardial Perfusion Imaging: A Head-to-Head Comparison

Heart disease is the second most common cause of mortality in Taiwan, mainly coronary artery disease (CAD).Quantitative coronary blood flow has been collected by dynamic single-photon emission computed tomography (Dynamic SPECT/CT) for CAD diagnosis in previous studies. However, few studies defined the extent of left ventricle (LV) ischemia on Dynamic SPECT/CT for predicting significant coronary artery stenosis. This study evaluates the extent of LV ischemic blockage in patients suspected of CAD who were referred by cardiologists. A total of 181 patients with suspected CAD were enrolled. They underwent 99mTc-Sestamibi (MIBI) Dynamic SPECT/CT survey before cardiac intervention. Dynamic SPECT/CT has better sensitivity (88%), specificity (96%), and accuracy (94%) compared with those of semi-quantitative MIBI MPI (more than 10%). Results indicated that5% of the LV ischemic extent can yield positive PCI results (>70% stenosis in coronary arteries) compared with the moderate abnormal extent of at least 15% of LV. When the percentage of combined moderate abnormal extent and ischemia extent of LV reaches 27.3%, positive PCI results may be indicated. This study revealed Dynamic SPECT/CT has greater sensitivity, specificity, and accuracy as compared with MPI. Thus, the severity of abnormal perfusion extent of LV on Dynamic SPECT/CT might be beneficial to predict positive PCI results in patients with significant suspicion CAD.

Rare Case of Severe Hypercalcemia Secondary to Atypical Sestamibi Negative Parathyroid Cystic Adenoma

Primary hyperparathyroidism (PHPT) is defined as excessive secretion of parathyroid hormone (PTH) originating from the parathyroid gland. The most common cause is a single parathyroid adenoma which is typically solid. Cystic parathyroid adenomas (CPA) are the cause of about 1–2% of cases of primary hyperparathyroidism. It is known that cystic parathyroid adenomas are a result of degeneration of an existing parathyroid adenoma. SestaMIBI is an imaging study based on uptake of radioactive technetium99 and used to localize parathyroid adenomas. We describe an unusual case of severe hypercalcemia secondary to 99mTc sestaMIBI negative atypical parathyroid cystic adenoma. A 56-year-old male presented to our facility with nausea and vomiting. His past medical history included hypertension and hepatitis C with no history of fractures or kidney disease. Physical examination was normal. Upon admission the patient was afebrile with blood pressure of 170/120 mmHg and heart rate of 62 bpm. Chemistry showed Calcium of 14.5 mg/dL (8.6–10.2mg/dL), phosphorus 2.2 (2.7–4.5) mh/dL, magnesium 1.8 (1.7–2.6)mg/dL, intact PTH of 375 (15–65) pg/mL, PTH-related peptide <2.0 pmol/L(<2 pmol/L), 25-OH vitamin D of 19 ng/ml (30–80), Creatinine 1.22 (0.7–1.2)mg/dL, alkaline phosphatase 95 (40–129) units/L. He was started on aggressive hydration, calcitonin 4 units/kg, 4 mg of IV Zolendroninc acid. Neck sonogram revealed a large, complex, predominantly anechoic lesion with solid vascular components and thick internal septations in the inferior and medial aspect of the right thyroid lobe measuring 3 x 2 x 5.5 cm. Findings were confirmed with CT of the neck. Since Sestamibi scan (planar and SPECT/CT) did not show uptake in parathyroid glands, the cyst was thought to be of thyroid origin. Fine needle aspiration was not able to detect cellular material, but PTH was >100 pg/ml on the FNA sample. Otolaryngology service was consulted for parathyroidectomy. During the surgical treatment, the right upper parathyroid gland was removed with no changes in serum PTH. Next, the cystic lesion was removed with normalization of serum PTH (from 218 pg/ml to 35.2 pg/ml respectively). Intraoperative frozen section analysis was read as a cystic parathyroid adenoma. The final pathology report revealed cystic parathyroid tissue favoring parathyroid adenoma with focal atypia. Hypercalcemia resolved. Conclusions: Atypical cystic parathyroid adenomas are a rare cause of PHPT. 90% of parathyroid cysts are nonfunctional. Above mention is a case of a patient presenting with hypercalcemic crisis secondary to cystic parathyroid adenoma, which posed a diagnostic challenge as both neck ultrasound and 99mTc sestaMIBI scan were inconclusive. These findings should trigger suspicion for functional parathyroid lesions. Cystic components should be evaluated for PTH levels and if significantly elevated should be treated as a parathyroid adenoma.

A Case of an Ectopic Parathyroid Adenoma With a Concomitant 99mTc-sestamibi-avid Papillary Thyroid Carcinoma

Background: The evaluation and management of parathyroid adenomas have improved over the years. Localization of parathyroid adenomas in patients with primary hyperparathyroidism was simplified with the use of 99mTc-sestamibi scintigraphy. In the advent of minimally invasive parathyroid surgery, use of radionuclide probes reduced the need for neck exploration and intraoperative frozen section leading to fewer complications, shorter operative time and hospitalization and rapid postoperative recovery. However, limitations of these techniques should be taken into consideration in certain cases. Clinical Case: A 60 year-old female diagnosed with primary hyperparathyroidism presented with recurrent nephrolithiasis and osteoporosis. Initial laboratory evaluation showed elevated serum calcium and intact PTH (1.54 mmol/L and 146 pg/mL, respectively). 99mTc-sestamibi scintigraphy showed a sestamibi-avid focus in the inferior aspect of the right lobe suggestive of a parathyroid adenoma or hyperplasia. Pre-operative neck ultrasound showed non-specific thyroid parenchymal changes and nodules on both lobes with benign sonographic features. She underwent radionuclide-guided focused right parathyroidectomy. The identified enlarged right inferior parathyroid gland registered a highest reading of 70 cps on radionuclide probe. Post-operatively, repeat intact PTH level was still elevated (171.2 pg/mL). There was an interval non-demonstration of the sestamibi-avid focus in the inferior aspect of the right thyroid lobe with an increased sestamibi uptake in the left thyroid lobe compared to the previous parathyroid scan. Histopathologic examination showed a normocellular parathyroid gland and a multifocal papillary thyroid carcinoma. She underwent total thyroidectomy with central neck dissection and 4 parathyroid gland exploration with intraoperative parathyroid hormone assay. However, serial PTH monitoring after left inferior parathyroidectomy and after bilateral partial superior parathyroidectomy still showed elevated levels. Histopathologic examination showed mildly enlarged, normocellular parathyroid gland. The bilateral carotid sheath, retropharyngeal region and superior mediastinum were explored but no ectopic parathyroid tissues were seen. Post-operatively, calcium and PTH were still elevated (1.48 mmol/L and 200.5 pg/mL, respectively). Conclusion: This case highlights the predicaments in the management of parathyroid adenomas, recognizing the possibility of false-positive sestamibi scans due to malignant thyroid nodules and the possibility of the two diseases occurring concurrently, albeit rare.