Detection of post-exercise stunning by early gated SPECT myocardial perfusion imaging: results from the IAEA multi-center study.

BACKGROUND: Transient post-ischemic LV dysfunction due to myocardial stunning in patients with coronary artery disease can be missed by conventional gated SPECT (GSPECT) acquisitions. The aim of this IAEA-sponsored multi-center study was to determine whether early post-exercise imaging is more likely to detect stunning than conventional without adversely affecting image quality or perfusion information. METHODS AND RESULTS: Patients undergoing exercise/rest GSPECT were enrolled in this international multicenter study. Post-exercise studies were acquired at 15 ± 5 minutes after radiotracer injection (Stress-1) and repeated at 60 ± 15 minutes (Stress-2). Rest studies (R) were acquired at 60 minutes post injection. A core laboratory quantitatively assessed perfusion pattern and LV blinded to the acquisition time. Ischemia was defined as summed stress score (SDS) ≥4, and stunning was defined as the difference between rest and post-stress LVEF (Δ-LVEF). In the 229 patients enrolled into the study, both image quality and perfusion information were similar between Stress-1 and Stress-2. Post-stress LVEF was associated with both ischemia and time of acquisition, with a significant correlation between SDS and Δ-LVEF, which was stronger at Stress-1 than Stress-2 in the ischemic compared to the non-ischemic population (r = 0.23 vs 0.08, P = 0.10). CONCLUSIONS: Early post-exercise imaging is feasible, and can potentially improve the detection of post-ischemic stunning without compromising image quality and perfusion data.

The early years of nuclear medicine: A Retelling.

Nuclear medicine history has its share of captivating personalities, controversial claims, and forgotten pioneers. Publications and documents that came out relatively recently, provide us with new perspectives on its history. Primary sourced material might contradict some of the long-held beliefs of the reader who only has a casual familiarity with the events, including basics such as who discovered radioactivity. Because of the nature of the specialty, the importance of the contributions of colleagues in related fields, like physics and chemistry, cannot be overstated. Many of the important discoveries were marked by serendipity, but the pioneers must be given credit for having the necessary insights to interpret the new phenomena correctly, sometimes turning perceived "failure" into novel scientific principles. In addition, most of our pioneers had to deal with inadequate facilities and funding, religious and racial discrimination, and even misogynism. The early history of nuclear medicine is presented in this article as a series of its most interesting anecdotes, from the early work on radioactivity, to the conception of the tracer principle, until the development of radioactive iodine therapy.

Comparison of Fixed versus Calculated Activity of Radioiodine for the Treatment of Graves Disease in Adults.

BACKGROUND: Radioactive iodine as a treatment modality has been shown in several studies to be a safe and effective therapy for Graves disease. However, there is still no uniformity regarding optimal dosing method. The aim of this study is to compare the efficacy of calculated and fixed dosing of radioiodine for the treatment of Graves disease. METHODS: A hundred twenty-two patients diagnosed with Graves disease were randomized to receive either fixed or calculated dose of radioiodine. Those randomized to fixed activity received either low fixed activity at 9.9 mCi for thyroid gland size <40 g or high fixed activity at 14.9 mCi for thyroid gland size 40 to 80 g, and those grouped to calculated activity received 160 µCi/g of thyroid tissue adjusted for 24 hours radioiodine uptake. Thyroid function tests (free thyroxine [T4] and thyroid stimulating hormone [TSH]) were monitored at 10, 16, and 24 weeks after radioactive iodine therapy. The primary outcome, treatment failure was defined as persistently elevated free T4 and low TSH. RESULTS: Of the 122 patients randomized, 56 in the fixed dose group and 56 in the calculated dose group completed the follow-up. At the end of 6 months, the percentage of treatment failure was 37.50% in the calculated dose group versus 19.64% in the fixed dose group with a relative risk of 0.53 (95% confidence interval, 0.28 to 0.98) favoring the fixed dose group. CONCLUSION: Fixed dose radioiodine has a significantly lower incidence of persistent hyperthyroidism at 6 months post-radioactive therapy.

Clinical utility of left ventricular ejection fraction reserve by stress thallium-201 myocardial gated single photon computed tomography among patients with and suspected coronary artery disease

BACKGROUND: Coronary microcirculation impairment with sequential decrease in cardiac function is reflected by abnormal left ventricular ejection fraction reserve (LVEFR),which precedes diagnostic evidence of myocardial insult. However, prognostic utility of LVEFR is less, if not least explored. The aim of this study was to evaluate the clinical utility of LVEFR in predicting major cardiac events (MACE) among patients with and suspected coronary artery disease (CAD).MATERIALS AND METHODS: A retrospective cohort study of 245 patients who underwent stress thallium-201 myocardial perfusion scan (MPS) was conducted. The patients were categorized as having normal or abnormal perfusion scan. Each group was subdivided into normal and abnormal LVEFR groups. All subjects were followed up for any major adverse cardiac events 36 months after MPS through review of hospital records.RESULTS: There was an overall increase in the likelihood of cardiac events with abnormal LVEFR (i.e., odds ratio of 2.99,p=CONCLUSION: Abnormal LVEFR can be used as an independent predictor of cardiac events which can be observed in subjects with normal and abnormal perfusion scans alike.

Value of Tl-201 imaging in predicting therapeutic I-131 uptake in patients with thyroglobulin-positive but I-131 scan negative differentiated thyroid cancer

BACKGROUND: Serum thyroglobulin assays and I-131 imaging and routinely employed for the detection of remaining functioning thyroid tissue after surgery and radioiodine therapy. However, the sensitivity of I-131 is suboptimal resulting in cases of positive thyroglobulin test but negative I-131 imaging, potentially creating a dilemma in subsequent therapeutic management. Other radiopharmaceuticals, such as TI-201 may offer better sensitivity, although it is not clear whether this contributes to the decision-making for subsequent I-131therapy. This prospective cohort study aimed to determine if Tl-201 imaging identified thyroid tissues that will take up therapeutic I-131, and to help define its clinical utility.METHODS: Fourteen consecutive patients who underwent surgery for well-differentiated thyroid cancer, had I-131 therapy at least eight months previously, and with elevated thyroglobulin (>10 ng/mL) but negative pre-therapy (111 MBq) I-131 whole body scan (WBS), were enrolled in the study. WBS was done using 56.74 MBq of Tl-201. All patients had repeat I-131 ablation (3.7-7.4GBq) one to two months after Tl-201 imaging. Post-therapy WBS was done four to seven days after.RESULTS: All 14 patients had papillary thyroid carcinoma. Ten patients had a positive Tl-201 scan. Of the 14 subjects, only two had a positive post-therapy I-131 WBS, both whom had a positive Tl-201 scan. Thallium-201 scanning showed a fairly high sensitivity (71%) in demonstrating thyroid remnants or metastases using a thyroglobulin level of >10 ng/mL as standard. However, a positivel Tl-201 scan only has a predictive value of 20% for subsequent uptake of therapeutic I-131 as shown in the post-therapy scan.CONCLUSION: Thallium-201 uptake correlates poorly with therapeutic I-131 uptake in thyroglobulin-positive, but I-131 scan-negative, differentiated thyroid cancer patients. Results of this study suggest that the presence of thyroid remnants and metastases on Tl-201 imaging is inappropriate as a basis for subsequent I-131 therapy.

Prognostic value of coronary flow reserve (CFR) by dipyridamole single-photon emission computed tomography (SPECT) sestamibi imaging in predicting future cardiac events

OBJECTIVES: Impairment of coronary flow reserve (CFR) precedes preclinical atherosclerosis. However, data are lacking regarding its prognostic utility using SPECT imaging. Thus, this study aimed to determine the clinical utility of CFR by sestamibi imaging in predicting future cardiac events in patients with normal and abnormal myocardial perfusion scan (MPS). METHODS: This was a prospective cohort study of 54 consecutive adult patients with suspected coronary artery disease referred to Nuclear Medicine Division, Philippine Heart Center for dipyridamole technetium-99m sestamibi SPECT MPS from August 2012 to September 2013. Patients with normal (summed stress score, SSS 4) perfusion scans were further subdivided based on their CFR whether normal (CFR> 2) or abnormal (CFR RESULTS: A prospective cohort of 54 consecutive patients with no known CAD, were enrolled in the study. Abnormal MPI revealed significantly lower CFR (1.64 + 0.47 vs. 1.19 + 0.36, p=0.005). The annual cardiac event rate increased in the presence of reduced CFR in spite of a normal MPI (from 0% to 6.9%), and was even higher when both MPI and CFR were abnormal (from 0% to 34.7%). In Kaplan-Meier analysis, patients with abnormal perfusion revealed-significantly higher incidence of cardiac events compared with normal perfusion (chi-square 4.93, p=0.027). There was a trend towards increased incidence of cardiac events in patients with abnormal CFR; however, this did not reach statistical significance (chi-square 0.61, p=0.434). CONCLUSION: A low CFR was associated with an increased incidence of MACE, particularly in the presence of abnormal perfusion findings.

Quantitative parameters in Tc-99m pertechnetate thyroid scintigraphy predict increased gland uptake function

BACKGROUND/OBJECTIVE: Direct measurement of gland uptake function is done by determining radioactive iodine uptake (RAID) values. Scintigraphic parameters in 99mTc0-4 thyroid scan have been shown to be moderately correlated with FT4 levels. This study aims to correlate these scintigrahic parameters with RAIU values and determine the cutoff that will predict increased gland uptake function.METHODOLOGY: Patients referred for thyroid scan and RAI uptake at the Philippine Heart Center were included in the study. RAW. values were correlated with thyroid salivary gland ratio, thyroid to background ratio, thyroid count and acquision time. These values were obtained by drawing appropriate regions of interest in the thyroid, salivary gland and the background.RESULTS: The four parameters were strongly correlated with RAI uptake values. The cut-off for the thyroid salivary gland ratio, thyroid to background ratio, total thyroid count and acquisition time that best predicts increased gland uptake were > 9.3, > 9.8, > 108134 counts, and CONCLUSION: The four scrim/graphic parameters can be used in determining the activity of the gland using thyroid imaging alone in the absence of RA1U values.

Myocardial perfusion scintigraphy in transposition of the great arteries after an arterial switch operation in infants

An abnormal myocardial perfusion is not uncommon in congenital heart defects (CHD). Many case reports and prospective studies were done describing myocardial peOision scintigraphy (MPS)findings after an arterial switch operation (ASO) among transposition of the great arteries (TCA), but to the best of the authors' knowledge, none have cited MPS findings in the immediate post-operative petiod. This paper aims to show two ckfferent clinicalthuatiomts in which (MPS) was used in the assessment of myocarchalfiinction in TCA immediatelyfollowing an arterial switch operation. Two male infants; aged 2 months and 4 months; both diagnosed with transposition of the great arteries presenting with past-operative morbidities after an arterial switch operation were referred to the Department of Nuclear Medicine/or evaluation. The younger infant was ditty discharged improved with an earlier magical intervention in contrast to the other who expired Bothpatients revealed a scintigraphic picture of myocarcbal ischemia and left ventricular a54ifiniction with concomitant right ventricular hypertrophy MPS .findings and reflective clinical pictures of patients with corrected congenital disease are yet to be/illy elticidated,.from the expected natural course after the stag/Cal intervention and long term complications ofsuch cases. The two cases present an invaluable avenue of non-invasive diagnostic modality using-MPS to assess probable pathologic mechanisms that occur after an arterial switch operation, and perhaps suggest incremental value not only in the post-operative period but in the preoperative scenario in the prognostication of these patients.

Association of coronary flow reserve by dipyridamole technetium-99m sestamibi single photon emission computed tomography with perfusion findings and risk factors for coronary artery disease

BACKGROUND: Blunting of coronary flow reserve (CFR) may precede overt ischemia. The study aimed to correlate CFR with perfusion findings and risk factors for coronary artery disease (CAD).METHODS: Fifty-four consecutive patients underwent dipyridamole-rest technetium-99m sestamibi single photon emission computed tomography (SPECT) on two separate days. CFR was computed as the quotient of myocardial blood flow (MBF= global tissue perfusion divided by arterial input function) at stress and at rest.RESULTS: CFR was significantly lower in patients with abnormal perfusion vs normals (p=0.005). Reduced CFR was noted in 83% of patients with normal SPECT. Lower CFR was seen in hypertensive patients with left ventricular hypertrophy (LVH) compared to those without LVH (p=0.029); likewise in DM vs no DM (p=0.121). Independent predictors of reduced CFR were age and extent of ischemia. CONCLUSION: Abnormal perfusion is associated with reduced CFR. In those with normal perfusion, there is a high prevalence of reduced CFR, which may be attributed to the presence of risk factors for CAD and LVH.

Left ventricular mass correlation between quantitative ECG-gated myocardial SPECT (QGS) and echocardiography

Left ventricular mass (LV mass) is an independent prognostic indicator of cardiovascular complications, and its regression due to therapy translates to positive clinical outcomes. Good correlation of LV mass between qualitative ECG-gated SPECT (OGS) and echocardiography has been reported, and this study aims to verify if such relationship applies in the local setting. Forty-five consecutive patients with normal myocardial perfusion SPECT and recent plain echocardiograms done in the same institution were retrospectively analyzed. Results show a significant correlation (y = 0.296x + 75.962, r = 0.491, p = 0.001) between the LV mass of the two imaging modalities, which was also observed in the TI-201  group (y= 0.256x + 80.325, r_=_0.442, p = 0.006), but not in the Tc-99m sestamibi group (y= 0.402x + 63.456, r_=_0.443, p = 0.272). The mean LV mass by OGS (122.0 ± 26.9) is significantly smaller compared with the mean LV mass by echo cardiography (155.5 ± 44.6), and the difference between the two procedures (mean ± SD: 39.7 ± 32.6, p

Diagnostic value of antithyroglobulin antibodies in the detection of recurrent differentiated thyroid carcinoma: A meta-analysis

The aim of this study is to determine the diagnostic accuracy of antithyroglobulin antibodies in predicting recurrent differentiated thyroid carcinoma. We searched PubMed (1990-2010) and Google Scholar (1990-2010). Citation searches, manual searches and screening of references of f included studies were done. Diagnostic studies that utilized antithyroglobulin antibodies as a predictor of recurrent differentiated thyroid carcinoma. The authors searched citations that correlated with the criteria using a data collection form generated in Review Manager 5 (REVMAN 5). The methodological quality was then assessed using Quality Assessment of Studies of Diagnostic Accuracy (QUADAS). Hierarchical summary receiver operating characteristic (HSROC) mete-analytical tool was used to estimate summary receiver operating characteristic (ROC) curves. Eight studies with 2116 participants with 182 patients with recurrent differentiated thyroid carcinoma were included. Pooled sensitivity and specifically were 63% and 79% respectively. SROC shows an overall are under the curve (AUC) of 0.712. Antithyroglobulin antibody has ability to predict recurrent differentiated thyroid carcinoma.

Relationship of body mass index and related anthropometric measurements on the image quality of thallium-201 and technetium-99m sestamibi myocardial perfusion imaging

The study aims to determine the relationship of body mass index (BMI) and related anthropometric measurements on the image quality of Tl-201 and Tc-99m sestamibi myocardial perfusion scans (MPS). A total of 163 scans were analyzed. A blinded experienced physician performed visual analysis on the scans image quality on two different occasions. Quantitative parameter used was the heart-to-lung ratio (HLR). Regression analysis was done to determine the association of HLR with BMI and myocardial tracer uptake, ROC curves were generated to establish BMI and HLR cut-off points. Increasing BMI was associated with visually poorer images in the Tl-201 MPS group (p 0.003) but not for the Tc-99m MPS group (p 0.065). It was also associated with decrease HLR and myocardial tracer upatake for both tracers (p <0.001). ROC curves revealed BMI cut-off points of 28 (Tl-201 p 0.000; Tc99m sestamibi p 0.004) for both procedures; HR cut-off values of 3.0 for Tl-201 )p 0.295) and 2.5 for Tc-99m sestamibi (p 0.875). the image quality of Tl-201 scans begins to deteriorate at a BMI of 28 and HLR of 3.0 with myocardial count density reduction (less than or equal to 6000 counts) translating to visually poorer images. On the other hand , image quality of Tc-99m sestamibi scans also tend to deteriorate similarly at a BMI of 28. However, in contrast to Tl-201, the lower HLR cut-off of 2.5 suggests a relatively higher myocardial count density (greater than or equal to 9000 counts) rendering the image quality to be still satisfactory for subjective assessment.

University of the Philippines-Philippine General Hospital revised clinical practice guidelines for the management of well-differentiated thyroid carcinoma of follicular cell origin / Journal of the ASEAN Federation of Endocrine Societies

In an effort to unify treatment approaches to patients with well-differentiated thyroid cancer of follicular cell origin, the Section of Endocrinology, Section of Nuclear Medicine, Department of Surgery, and Department of Otorhinolaryngology of the Philippine General Hospital formulated and published a clinical practice guideline on the management of well-differentiated thyroid cancer in 2008. In recognition of the new literature on thyroid cancer, as well as the questions that have arisen from the use of the guideline, the group reconvened in 2011 to review and update the clinical practice guideline designed for patients seen at the Philippine General Hospital. This article summarizes the latest revisions and recommendations.

Resolving hypoplastic dilemma: Lung perfusion scintigraphy in a case of congenital cystic adenomatoid malformation (CCAM)

Congenital cystic adenomatoid malformation is a rare bronchopulmonary malformation resulting from an arrest in lung development between 4th and 7th week of fetal life. It typically presents as respiratory distress in the neonatal period and recurrent pulmonary infections in adults; and is sometimes associated with other congenital abnormalities [especially CCAM Type II]. Chest roentgenograms and CT scan are the usual modalities of choice in its initial evaluation and histopathology done post-operatively establishes the diagnosis. Ventilation-Perfusion [VQ] scintigraphy is of paramount importance in the routine assessment of CCAM patients but is often disregarded. This paper presents the incremental value of doing a lung perfusion scintigraphy and aims to emphasize the significance of performing a VQ scan in such cases.

Whole body bone scintigraphy correlation in a case of multiple extramedullary plasmacytoma

Multiple extramedullary (soft tissue) plasmacytoma is a rare neoplasm of plasma cells. This is a case of a 63-year-old male who presented with back pain and a one month history of a painful, progressively growing mass at the right anterior chest wall. Since radiographs and computed tomography of the chest showed lytic lesions on the ribs and L4 compression deformity, the patient was referred for whole body bone scintigraphy to evaluate the remainder of the skeleton. Bone scintigraphy revealed osteoblastic lesions and osteolytic lesions in the thoracic cage. Diagnosis of plasmacytoma was established by biopsy and confirmation of microscopic characteristics and immunohistochemical staining.

Bridging crossroads of congenital lobar emphysema--Lung perfusion scintigraphy: A guide towards the right path

Congenital lobar emphysema (CLE) is a life-threatening but potentially reversible lung abnormality of unknown etiology that can present a diagnostic dilemma. Imaging procedures are helpful for early diagnosis. This paper aims to present the scintigraphic features of CLE in a two-year-old male in correlation with other diagnostic modalities. Lung perfusion scintigraphy revealed globally diminished perfusion to the left lung. High Resolution Computed Tomography (HRCT) of the chest showed intrinsic narrowing of the distal left mainstem bronchus. CT scan of the Pulmonary Arteries (CTPA) showed a small left main pulmonary artery. Lung perfusion scintigraphy in CLE is characterized by markedly attenuated vascularity of the involved lobe with consequent decreased perfusion, and increased to normal perfusion in the unaffected lobe. It plays a vital role in the early diagnosis and management of pediatric pulmonary diseases presenting with a diagnostic dilemma, particularly in cases where it can preclude more invasive diagnostic procedures.

Anomalous origin of the left coronary artery arising from the pulmonary artery: Myocardial perfusion scintigraphy findings

Anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) is a rare congenital cardiac disease with serious complications. This is a case of a three-year-old female who was initially diagnosed and managed as a case of dilated cardiomyopathy. A 2-D echocardiogram showed the left main coronary artery to be coming from the pulmonary artery. The patient was referred for myocardial perfusion scintigraphy (MPS) to determine viability prior to surgical revascularization. MPS showed absent myocardial perfusion in the apex and apical anterior segments and thinned-out perfused myocardium in the midventricular to basal anterior segment and apical to basal inferior and lateral walls. This is consistent with markedly reduced perfusion in the segments supplied by the anomalous left coronary artery distribution. While echo cardiography and angiography are used to diagnose ALCAPA, the roles of MPS are to provide information regarding the viability of the areas supplied by the anomalous left coronary artery and to assess postoperative myocardial perfusion.

Myocardial perfusion scintigraphy in tetralogy of fallot prior to total correction of a non-patent shunt

This paper presents a clinical situation in which a Technetium 99m sestamibi myocardial perfusion scintigraphy (MPS) with dipyridamole was used as part of the preoperative evaluation in a 15 year old female with Tetralogy of Fallot. MPS revealed no evident inducible myocardial ischemia, depressed LV wall function and RVH but with good RV function. There are many different techniques for imaging and studying patients with Tetralogy of Fallot (TOF). Echocardiography, ventriculography and invasive angiography remain the mainstay in its evaluation. However, the presence of coronary anomalies in these patients is very common and has negative effect on myocardial perfusion, either preoperatively or postoperatively. Hence, MPS plays an essential role in providing complete assessment in this group of patients.

Value of post-therapy whole body scintigraphy in predicting the need for subsequent radioactive iodine therapy in patients with well-differentiated thyroid carcinoma

INTRODUCTION: Patients with well-differentiated thyroid carcinoma (WDTC) may require more than one session of radioactive iodine therapy (RAIT). This study was conducted to determine if post-therapy whole body scintigraphy (PTWBS) can identify patients who will require repeat RAIT due to persistent disease. METHOD: The records of patients with WDTC who were referred to the Philippine General Hospital for RAIT from 2005-2007 were reviewed in this retrospective cohort study. PTWBS results (number of remnants, area of remnants, and presence of metastasis) of patients who had repeat RAIT (based on laboratory and clinical evidence of persistent disease) were compared with those of patients who did not have repeat RAIT. Multiple logistic regression analysis was done. RESULTS: Forty-five of 99 patients in the study [45%, 95% Confidence Interval (CI): 35 had repeat RAIT. Thirty-six of 38 patients (95%) with metastases on PTWBS required repeat RAIT, while only 9 of 61 patients (15%) with no scan evidence of metastases required subsequent therapy. Controlling for age group (age), the odds ratio was 102 (95% CI: 20 . Positive and negative predictive values were 95 and 85% respectively. The same results were obtained using metastases alone as a predictor. Twenty-six patients had extra-cervical metastases by PTWBS and all required repeat RAIT. The number and aggregate size of thyroid remnants by PTWBS, however, were not found to be predictive of the need for repeat therapy. CONCLUSION: The presence of functioning metastases seen on PTWBS was highly predictive of the need for repeat RAIT.

Nitroglycerine-augmented myocardial perfusion scintigraphy for the assessment of prognosis and myocardial viability

The aims of this study were to determine the prognostic value and the accuracy of nitrate-augmented Tc-99m myocardial SPECT for myocardial viability detection. Patients with angiographic CAD and LV wall motion abnormality by MUGA were included in the study. Rest Tc-99m sestamibi SPECT MPS was performed on two consecutive days, once with 0.6 mg sublingual nitroglycerin and once without. Perfusion was graded semi-quantitatively. Reversibility score was calculated as the difference between nitrate-augmented and rest imaging perfusion scores. Repeat rest SPECT MPS was performed after at least 6 months and all patients were followed up for at least 12 months to determine the occurrence of cardiac events. Thirty-five patients were included in the study. Five patients died from myocardial infarction during the follow-up period. Eleven patients had follow-up SPECT, with five of them done after revascularization. Defect score improved significantly after revascularization compared without revascularization (7.4 versus 0.3, p=0.02). Reversibility scores correlated poorly with the subsequent occurrence of cardiac events in patients treated medically. There was no significant increase in LVEF detected after revascularization even if the patients had a positive reversibility score. By this parameter, nitrate-augmented MPS could not accurately assess myocardial viability. However, with nitrate-augmentation, defect scores significantly improved and were more predictive of post-revascularization scores compared to the rest scores. These suggest the possibility for enhanced detection of potentially viable myocardium with nitrate MPS. And due to its simplicity and safety, the routine use of nitrate-augmentation in clinical practice may be recommended.