Anterior Planar Images Research Articles

Role of 99mTc-sestamibi SPECT in accurate selection of primary hyperparathyroid patients for minimally invasive radio-guided surgery

Dear Sir, We read with interest the recent paper by Rubello et al. entitled “Role of Tc-sestamibi SPECT in accurate selection of primary hyperparathyroid patients for minimally invasive radio-guided surgery” [1]. Minimally invasive radio-guided surgery (MIRS) is widely employed for primary hyperparathyroidism caused by a solitary parathyroid adenoma. Since an intraoperative gamma probe is used, significant sestamibi uptake by the adenoma is important [2, 3]. Obviously, as the authors underline, radiation attenuation problems may cause underestimation of the sestamibi uptake by adenomas in an anterior planar image, resulting in doubt as to the appropriateness of MIRS in some cases. In this regard the authors report an interesting finding, namely that the parathyroid to background (P/B) ratio derived from SPECT correlates well with the intrasurgery P/B ratio; this means that using SPECT it is possible to predict the intraoperative measurement obtained with the gamma probe, thus allowing better patient selection for MIRS. However, we believe that this finding is not going to have a significant impact on the selection of patients for MIRS since only patients with a high probability of having a solitary adenoma are candidates for MIRS [4]. In our experience most of these patients demonstrate a P/B ratio significantly higher than the threshold, referred to by the authors, of 1.2 in the anterior planar image and thus do not require any quantitative confirmation. In the case of deeply located adenomas, despite the relatively reduced sestamibi intensity in the anterior planar image, they will still be well recognised as parathyroid lesions and any doubt about the appropriateness for MIRS in those cases can be dispelled just by knowing that the adenoma is located deeply. In this regard we visually estimate the depth and at the same time take into account the attenuation effect on sestamibi uptake from adenomas by using oblique planar imaging in all cases, rather than the time-consuming and rather complicated SPECT technique. Oblique planar imaging is easy to perform and very valuable even when the adenoma is behind the thyroid gland [5, 6]. In the presented study the ratio derived from SPECT was useful in only 1/22 patients although 7/22 adenomas were deeply located. The quantification might possibly be useful in estimating the appropriateness of the sestamibi uptake for MIRS in a few borderline cases. However, trying to include these patients will inevitably increase the probability of multiple gland disease since it is well known that frequently only the largest gland is visible in hyperplasia, especially in the early stages, when the size of the other glands remains below the sensitivity of the techniques used [7, 8]. The result will then be that more operations will be changed to bilateral exploration assuming that rapid PTH measurement is available. In this regard, SPECT, because of its slightly better sensitivity compared with planar imaging, would be most useful not in selecting more patients but rather in excluding some on the basis of the identification of more than one parathyroid lesion in cases of multi-gland disease. Nevertheless, ultrasound can contribute this important information even better than SPECT. In conclusion, we believe that in the selection of eligible patients for MIRS, quantification is not needed and that performance of SPECT exclusively for this purpose is not justified. Eur J Nucl Med Mol Imaging (2007) 34:607–608 DOI 10.1007/s00259-006-0332-y

Serial hypoxia imaging with 99mTc-HL91 SPECT to predict radiotherapy response in non-small cell lung cancer

7143 Background: To evaluate the relationship between 99mTc-HL91 (99mTc labeled 4,9-diaza-3,3,10,10-tetramethyldodecan-2,11-dione dioxime) SPECT (single photon emission computed tomography) hypoxia imaging and the radiotherapy outcome and also to assess changes in tumor oxygenation during the course of treatment. Methods: 32 patients with pathologically proven non-small cell lung cancer received three-dimensional conformal radiotherapy were enrolled into the study. All patients were performed 99mTc-HL91 SPECT scanning at one or two days before radiotherapy. 18 patients were also performed during radiotherapy (30–40 Gy) and one or two days after radiotherapy. Anterior, posterior and lateral planar images were collected at 2 hours, 4 hours and 6 hours respectively after intravenous injection approximately 740MBq 99mTc-HL91. Regions of interest (ROIs) were drawn in the tumor and contralateral normal lung tissue and the radioactivity ratios of tumor to normal tissue (T/N) were calculated. Results: The relationship between T/N ratios at 4h images after injection which was shown as the best of three acquired images before radiotherapy and the response and over survival to radiotherapy were analyzed for all 32 patients. The results of 99mTc-HL91 imaging of 32 patients correlate well with radiotherapy response (P = 0.049) and also patient survival (P = 0.043). The average T/N value of 18 patients who receiving serial scanning was 1.57 ± 0.18, 1.44 ± 0.19 and 1.30 ± 0.14 respectively. There was significant statistic difference between these three groups (P = 0.000). Conclusions: HL91 SPECT imaging identified the hypoxia status and changes during radiotherapy in lung cancer. It was confirmed that hypoxia imaging with HL91 SPECT before treatment may predict radiotherapy response and patient survival. The relationship between T/N ratio and radiotherapy outcome in NSCLC [Table: see text] No significant financial relationships to disclose.

Prognostic value of cardiac I-123 metaiodobenzylguanidine imaging in patients with non–insulin-dependent diabetes mellitus

123I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy is a useful tool for diagnosing cardiac autonomic neuropathy (CAN) in non-insulin-dependent diabetes mellitus (NIDDM). However, the long-term prognostic value for cardiac events or mortality in NIDDM has not been clarified. We investigated the long-term prognostic value of cardiac MIBG imaging for both cardiac event and mortality owing to a variety of causes of death in NIDDM. 144 NIDDM patients were analyzed retrospectively with the end-points of a cardiac event and various causes of mortality. The heart-to-mediastinum uptake ratio on the delayed image (H/M [d]) was obtained from anterior planar imaging. The mean follow-up period was 7.2+/-3.2 years. Seventeen patients had a cardiac event onset and 7 patients died during observation. During the same observation course, 16 patients died, including some who died of cardiac event. Both multivariate and univariate analyses revealed that decreased H/M (d) (<1.7) was the independent predictor of long-term mortality for a variety of causes of death. Although the value of H/M (d) was not a significant prognostic factor for predicting a cardiac event, CAN, diagnosed by a combination of H/M (d) and coefficient variance of RR interval, was an independent predictor for the cardiac event in NIDDM. MIBG myocardial scintigraphy was useful for predicting cardiac events and long-term mortality in NIDDM.

Relation between Tc-99m sestamibi uptake and biological factors in hyperparathyroidism

The aim of this study was to evaluate the relation between uptake ratios of Tc-99m sestamibi (MIBI) and tumor volume, serum biochemical values (i-PTH, Ca, P) and oxyphil cell content. The study population consisted of 19 patients (2 M, 17 F; mean +/- SD: 47 +/- 12 y). Anterior planar images of the neck and chest were acquired early (15 min) and triple late phase (1, 2 and 3-4 h) after intravenous injections of 740 MBq MIBI. Each of the surgical materials was reviewed retrospectively. The percentage of cell type (chief, oxyphil and clear cells) in the tumors was calculated by light microscopy. The uptake ratio obtained from L1 (1 hour) phase was found to be higher than the uptake ratio obtained from early phase, and the difference was statistically significant (1.57 +/- 0.34 and 1.43 +/- 0.29, p = 0.004, respectively). There was no significant correlation between uptake ratios that were obtained from 4 different imaging phases and lesion volumes, i-PTH levels and calcium levels (p > 0.05). However, there was a significant adverse correlation between L2 and L3 uptake ratios and serum phosphorus values (r = -0.44, p = 0.04 and r = -0.46, p = 0.04, respectively). Additionally, no significant correlation between MIBI uptake ratios of each imaging phase and the laboratory data, volume of lesion or oxyphil percentage volume was found after the multiple regression analysis (E: p = 0.46, r = 0.49; L1: p = 0.24, r = 0.58; L2: p = 0.27, r = 0.57; L3: p = 0.32, r = 0.55, respectively. There was no correlation between gland oxyphil percentage volume and MIBI uptake ratios (p > 0.05). The results of our study show that the optimal imaging times after intravenous injection of MIBI are 15 minutes and 1 hour because of the shorter examination time without loss of diagnostic ability. In the present study, there was no significant correlation between MIBI uptake ratios and increased gland volume, or serum Ca and i-PTH levels. Besides, we think that oxyphil cell content may not have a main effect on MIBI uptake and retention. The fact of an adverse relation between phosphorus and MIBI retention in our study suggests that phosphorus level should be considered prior to MIBI imaging.

Comparison of cardiac to hepatic uptake of 99mTc-tetrofosmin with and without adenosine infusion to predict the presence of haemodynamically significant coronary artery disease

Coronary artery disease impairs cardiac vasodilatory reserve. A low ratio of cardiac to hepatic vasodilatory reserve may be diagnostic for coronary artery disease. To compare the ratio of cardiac to hepatic uptake of 99mTc-tetrofosmin during adenosine infusion and at rest in patients with and without coronary artery disease in order to determine whether the ratio was significantly different between the two groups. Fifty-one patients who underwent coronary angiography and adenosine stress myocardial perfusion imaging using 99mTc-tetrofosmin were studied retrospectively. Anterior planar images from the single photon emission computed tomography (SPECT) raw data were used to draw regions of interest around the heart and liver. The counts per pixel in each region were used to calculate the stress ratio (SR) and the rest ratio (RR) as follows: SR = (cardiac counts per pixel)at stress/(hepatic counts per pixel)at stress; RR = (cardiac counts per pixel)at rest/(hepatic counts per pixel)at rest. The SR and SR/RR ratios were compared in patients with and without significant coronary artery disease. Receiver operating characteristic curves were drawn for SR and SR/RR. The SR and SR/RR ratios were significantly lower in patients with significant coronary artery disease than in patients without (P<0.001). A cut-off ratio of SR/RR = 1.00 yielded 87% sensitivity and 74% specificity for the detection of significant coronary artery disease. Combining SR/RR with standard SPECT image interpretation increased the sensitivity without substantially changing the specificity in comparison with standard SPECT image interpretation only. Comparison of cardiac to hepatic 99mTc-tetrofosmin concentration at rest and under adenosine stress provides useful diagnostic information for the assessment of the presence of significant coronary artery disease.

Depreotide scanning in sarcoidosis: a pilot study.

To determine whether sarcoidosis results in uptake on (99m)Tc-labeled depreotide (DP) scintigraphy and to generate preliminary data to guide the development of future trials exploring this imaging modality in sarcoidosis patients. Prospective cohort trial among a convenience sample of patients with sarcoidosis. Tertiary care medical center pulmonary clinic. Subjects in whom sarcoidosis has been diagnosed based on a biopsy revealing nonnecrotizing granulomas. Two hours after IV administration of (99m)Tc-DP, all patients underwent whole-body anterior and posterior planar imaging, followed by thoracic single-photon emission CT scanning. Images were interpreted by two nuclear medicine physicians who were blinded to the patient's clinical status. The study cohort included 22 subjects (mean [+/- SD] age, 41.3 +/- 9.3 years; 40% female). Approximately half of the cohort had stage I disease determined by chest radiographs (CXRs). The results of (99m)Tc-DP scintigraphy were positive for sarcoidosis in 18 individuals (81.8%; 95% confidence interval, 59.7 to 94.8%). Of the four persons lacking (99m)Tc-DP uptake, all had normalized their CXRs since the time of presentation. In the entire sample, the intraclass correlation between radiographic stage determined by CXR vs that determined by (99m)Tc-DP scintigraphy was robust (kappa = 0.79; p = 0.0005). Among patients with positive (99m)Tc-DP scan findings, the correlation was stronger (kappa = 0.94; p < 0.0001). Flow rates and lung volumes were lower in patients with parenchymal activity on (99m)Tc-DP scintigraphy (mean FEV(1), 68.6 +/- 13.9% predicted vs 84.5 +/- 10.7% predicted, respectively [p = 0.012]; mean FVC, 74.0 +/- 16.0% predicted vs 88.4 +/- 12.7% predicted [p = 0.041]). (99m)Tc-DP scintigraphy correctly identified all sites of known nonpulmonary visceral involvement with sarcoidosis. The results of (99m)Tc-DP imaging are often positive in sarcoidosis patients, and correlate with disease stage determined by CXR and pulmonary function. (99m)Tc-DP scintigraphy does not preclude the need for biopsy if this is indicated to confirm the diagnosis of sarcoidosis or to exclude the possibility of malignancy. (99m)Tc-DP scintigraphy merits further study in the evaluation and management of sarcoidosis.

Folate-scan in subjects with suspected metastatic renal cell carcinoma

4751 Background: The folate receptor (FR) is overexpressed by different cancer types, including renal cell carcinoma. A folate-targeted imaging agent (EC20) could provide an alternative means of selecting folate receptor-positive (FR+) patients that may benefit from folate-targeted therapies. Methods: 40 subjects with known metastatic renal cell carcinoma were enrolled into the study and increased uptake of Folate-Scan in tumors was correlated with the immunohistochemical (IHC) staining. Formalin-fixed, paraffin-embedded tissue samples, primary and metastatic sites were analyzed for the folate receptor by an IHC assay. Three lesions were identified as target lesions on the subject's conventional image. Mid-thigh to head anterior and posterior planar images were then obtained 1 –2 hours following EC20 administration. SPECT images of the region known to contain the index lesion(s) as identified by the subject's CT or MRI were obtained immediately after acquisition of the planar images. The amount of FS uptake in the tumors were coded as no uptake, mild uptake, or marked uptake. Results: 29 out of the 40 subjects who have been scanned, data is available. 22 (74%) of the subjects were Folate-Scan positive, 15 (52%) of the subjects were positive on both the IHC and the Folate-Scan and 7(24%) were positive on the Folate-Scan with negative IHC. Of the 112 lesions identified on CT and evaluated on Folate-Scan, 69 lesions (61%) were positive for Folate-Scan uptake (mild or marked uptake of FolateScan), 43 lesions (38%) did not show any Folate-Scan uptake. Data suggest that larger lesions show mild or marked uptake of Folate-Scan whereas smaller lesions show little or no uptake of Folate-Scan. Conclusions: Primary tumors are not always folate receptor positive. It is difficult to obtain a current tissue sample from a metastatic site which has proven to be more positive. Folate-Scan is a non-invasive procedure that can identify folate receptors in recurrent or metastatic disease without the need for biopsy. The entire body can be scanned in real time which would prevent the need for biopsies in patients. Author Disclosure Employment or Leadership Consultant or Advisory Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Endocyte, Inc.

Folate-scan in subjects with suspected metastatic renal cell carcinoma

4751 Background: The folate receptor (FR) is overexpressed by different cancer types, including renal cell carcinoma. A folate-targeted imaging agent (EC20) could provide an alternative means of selecting folate receptor-positive (FR+) patients that may benefit from folate-targeted therapies. Methods: 40 subjects with known metastatic renal cell carcinoma were enrolled into the study and increased uptake of Folate-Scan in tumors was correlated with the immunohistochemical (IHC) staining. Formalin-fixed, paraffin-embedded tissue samples, primary and metastatic sites were analyzed for the folate receptor by an IHC assay. Three lesions were identified as target lesions on the subject's conventional image. Mid-thigh to head anterior and posterior planar images were then obtained 1 –2 hours following EC20 administration. SPECT images of the region known to contain the index lesion(s) as identified by the subject's CT or MRI were obtained immediately after acquisition of the planar images. The amount of FS uptake in the tumors were coded as no uptake, mild uptake, or marked uptake. Results: 29 out of the 40 subjects who have been scanned, data is available. 22 (74%) of the subjects were Folate-Scan positive, 15 (52%) of the subjects were positive on both the IHC and the Folate-Scan and 7(24%) were positive on the Folate-Scan with negative IHC. Of the 112 lesions identified on CT and evaluated on Folate-Scan, 69 lesions (61%) were positive for Folate-Scan uptake (mild or marked uptake of FolateScan), 43 lesions (38%) did not show any Folate-Scan uptake. Data suggest that larger lesions show mild or marked uptake of Folate-Scan whereas smaller lesions show little or no uptake of Folate-Scan. Conclusions: Primary tumors are not always folate receptor positive. It is difficult to obtain a current tissue sample from a metastatic site which has proven to be more positive. Folate-Scan is a non-invasive procedure that can identify folate receptors in recurrent or metastatic disease without the need for biopsy. The entire body can be scanned in real time which would prevent the need for biopsies in patients. Author Disclosure Employment or Leadership Consultant or Advisory Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Endocyte, Inc.

Clinical relationship of myocardial sympathetic nervous activity to cardiovascular functions in chronic heart failure: assessment by myocardial scintigraphy with 123I-metaiodobenzylguanidine.

The aim of this study was to clarify the relationship between cardiac sympathetic nervous activity (SNA) assessed by radioiodinated metaiodobenzylguanidine (123I-MIBG), an analogue of norepinephrine and cardiovascular functions in patients with chronic heart failure (CHF). Subjects were 17 patients with CHF. A dose of 111 MBq of 123I-MIBG was administered intravenously, and 5-minute anterior planar images were obtained 15 minutes (early image) and 3 hours (delayed image) after the injection. The heart/mediastinum (H/M) count ratio was defined to quantify cardiac 123I-MIBG uptake. The washout ratio (WR) of 123I-MIBG from the heart was calculated as follows: (early counts-delayed counts)/early counts x 100 (%). Echocardiography was performed on all patients within 1 week of 123I-MIBG scintigraphy to measure stroke volume index (SVI). Blood pressure and heart rate (HR) in the resting state were also recorded to calculate cardiovascular functions including cardiac output, pulse pressure (PP), and mean blood pressure. Significant linear correlations were found between the early H/M ratio of 123I-MIBG and SVI, and between the delayed H/M ratio of 123I-MIBG and SVI, respectively. WR of 123I-MIBG was correlated with HR, and was inversely correlated with SVI and with PP, respectively. It is likely that a decrease in SVI is associated with enhanced cardiac SNA in severe CHF. 123I-MIBG scintigraphy is effective in assessing the cardiac functional status and SNA in patients with CHF in vivo. Moreover, changes in PP and HR indicate well alteration in SNA.

Dobutamine Gated Blood Pool Scintigraphy Predicts the Improvement of Cardiac Sympathetic Nerve Activity, Cardiac Function, and Symptoms After Treatment in Patients With Dilated Cardiomyopathy

We evaluated whether dobutamine gated blood pool scintigraphy (DOB-GBP) can predict improvement in cardiac sympathetic nerve activity and cardiac function after beta-blocker therapy in patients with dilated cardiomyopathy (DCM). Twenty-two patients with DCM underwent DOB-GBP to measure left ventricular ejection fraction (LVEF) at rest, and during 5, 10, and 15 microg/kg/min of dobutamine infusion before therapy. Examinations were performed before and after 1 year of therapy. The heart/mediastinum count (H/M) ratio and total defect score (TDS) were determined for 123I-meta-iodobenzylguanidine images from anterior planar image and single-photon emission CT images. LVEF and left ventricular end-diastolic dimension (LVDd) were determined by echocardiography. After 1 year of treatment, the echocardiographic LVEF improved > 5% in 11 patients (group A), but did not improve in the remaining 11 patients (group B). Before treatment, TDS, H/M, LVEF, and LVDd were similar in both groups. However, there was a greater increase in the LVEF during dobutamine infusion in group A than in group B (21 +/- 8% vs 9 +/- 3%, p < 0.001). If a critical value of 15% for the DeltaLVEF was used to predict the improvement in LVEF after treatment, the sensitivity was 91% and specificity was 82%. The TDS, H/M ratio, LVDd, and New York Heart Association functional class improved in group A to a greater extent than in group B. DOB-GBP can be used to predict improved cardiac sympathetic nerve activity, cardiac function, and symptoms after treatment in patients with DCM.

Evaluation of microcirculation in Buerger's disease using 201thallium/99mtechnetium macroaggregated albumin scintigraphy.

In the current study, 10 patients with Buerger's disease (thromboangiitis obliterans) and seven control patients with atherosclerosis obliterans (ASO) were evaluated for microvascular disturbance. After exercising for 1 min, patients were injected with 37 MBq 201thallium (201Tl) intra-arterially, and anterior planar images of the feet and whole body images of the lower extremities were taken. The same procedure was repeated after 1 week using 185 MBq 99mtechnetium macroaggregated albumin (99mTc-MAA). Rectangular regions of interest were drawn on the 201Tl and 99mTc-MAA images, and 201Tl/99mTc-MAA uptake ratios were calculated. 201Tl/99mTc-MAA ratios of the toes of those with Buerger's disease were significantly lower than those of ASO cases, whereas no significant difference was found for the lower limbs and feet. These findings may be explained by disturbances of microvascular regulation observed in Buerger's disease.

Lung Uptake of Technetium-99m Tetrofosmin in Healthy Subjects Is Related to Smoking Habits

To determine the influence of smoking on lung uptake of technetium-99m tetrofosmin (Tc-TF) during myocardial perfusion imaging, we examined 50 healthy subjects with normal myocardial perfusion single photon emission computed tomography findings, normal coronary angiograms, and no evidence of left ventricular hypertrophy. The 50 healthy subjects were divided into two groups. Group 1: 25 healthy subjects had smoking histories of at least 10 pack-years. Group 2: 25 healthy subjects were nonsmokers. Lung to heart ratios (L/H ratios) calculated from anterior planar images during exercise and rest states of Tc-TF myocardial perfusion imaging were obtained for all of the 50 healthy subjects. L/H ratios calculated from Tc-TF myocardial perfusion imaging in smokers were significantly higher than in nonsmokers during both exercise and rest states. However, no significant difference in L/H ratios was found between exercise and rest states in smokers and nonsmokers. In addition, a positive but nonsignificant correlation was found between smoking pack-years and either rest or exercise L/H ratios. When L/H ratios are used as a clinical diagnostic tool in Tc-TF myocardial perfusion imaging, we must consider that L/H ratios in smokers are higher than in nonsmokers.

Increased prognostic value of combined myocardial perfusion SPECT imaging and the quantification of lung Tl-201 uptake.

The authors wanted to identify those patients assessed by exercise SPECT in whom the quantification of lung Tl-201 uptake helps to evaluate disease prognosis. One hundred forty-nine patients (114 men, 35 women; 74 after myocardial infarction [MI]; mean age, 54 +/- 9 years) underwent exercise Tl-201 SPECT. The SPECT patterns were divided into normal (n = 45), fixed defects (n = 29), and inducible ischemia (n = 75). Anterior planar imaging was performed before SPECT acquisition to calculate the lung-to-heart ratio (L:H). During an average follow-up of 20 +/- 9 months, eight patients had died of cardiac causes and 13 patients experienced nonfatal MIs. Among the 45 patients with normal perfusion, no cardiac event was observed and the L:H ratio was not helpful for risk stratification. In 29 patients with fixed defects, four cardiac deaths occurred (all in patients with L:H ratios >0.5; annual event rate, 21.1% for L:H ratios >0.5 compared with 0% for L:H ratios <0.5; chi-square = 4.07, P < 0.05). Among the 75 patients with ischemia, 4 died and 13 had nonfatal MIs (annual event rate, 15.4% for L:H ratios >0.5 compared with 13% for L:H ratios <0.5; P = NS). These findings suggest a benign prognosis in patients with normal SPECT (regardless of the L:H ratio). Conversely, all patients with ischemia are at high risk for future cardiac events. Quantification of the Tl-201 lung uptake seems to be valuable in evaluations of disease prognosis, especially in patients with fixed defects.

Impact of an abbreviated adenosine protocol incorporating adjunctive treadmill exercise on adverse effects and image quality in patients undergoing stress myocardial perfusion imaging

Background. Limited data are available about the effects of adjunctive treadmill exercise on adverse effects and the image quality of adenosine perfusion imaging. This study compared the incidence of adverse effects and image quality between standard 6-minute adenosine perfusion imaging and a stress test incorporating a 4-minute adenosine infusion with low-level treadmill exercise. Methods and Results. Nineteen patients underwent both a 6-minute adenosine technetium-99m sestamibi single photon emission computed tomography (SPECT) imaging study and a 4-minute adenosine Tc-99m sestamibi SPECT study with 6 minutes of simultaneous low-level treadmill exercise. Symptoms were recorded at 1-minute intervals during the stress and recovery periods. Heart-to-liver and heart-to-lung count ratios were determined from anterior planar images. More adverse effects were experienced during the standard adenosine study than during the adenosine study with low-level exercise (2.7 ± 1.4 vs 1.4 ± 1.1,P = .0003). The duration adverse effects were experienced was longer during the standard 6-minute adenosine protocol (6.6 ± 2.1 minutes vs 3.2 ± 2.8 minutes,P < .0001). Additionally, the symptom-severity scores were higher with the standard adenosine study (15.5 ± 9.8 vs 4.5 ± 5.1, P < .0001). The heart-to-liver ratios were noted to be higher in the 4-minute adenosine protocol with low-level exercise (1.0 ± 0.3 vs 0.6 ± 0.2, P = .0003). Conclusions. In comparison with standard 6-minute adenosine perfusion imaging, a protocol incorporating a 4-minute adenosine infusion with low-level treadmill exercise results in a marked reduction in the quantity and severity of adverse effects and an improvement in image quality. (J Nucl Cardiol 2000;7:584-9.)

Thallium-201 right lung/heart ratio during exercise in patients with coronary artery disease: relation to thallium-201 myocardial single-photon emission tomography, rest and exercise left ventricular function and coronary angiography.

The aim of this study was to correlate lung thallium-201 uptake on exercise with 201Tl single-photon emission tomography (SPET) myocardial perfusion imaging, rest and exercise equilibrium radionuclide angiographic and coronary angiographic findings in patients with coronary artery disease (CAD) using a simple, reproducible lung/heart (L/H) ratio that would be easy to use in clinical practice. L/H ratio was defined on the anterior planar image obtained during exercise 201Tl SPET acquisition as the mean counts per pixel in an entire right lung field region of interest divided by the mean counts per pixel in the hottest myocardial wall region of interest. We studied 103 patients. Fifty-nine patients (group I) with <5% likelihood of CAD were used as a reference group. In 44 CAD patients (group II), L/H ratio was compared with 201Tl SPET, radionuclide angiographic and coronary angiographic variables. The group I L/H ratio of 0.35+/-0.05 (mean +/-1 SD) was significantly lower (P<0.001) than the group II L/H ratio of 0. 45+/-0.10. An L/H ratio >0.45 (mean + 2 SD in group I) was considered abnormal. In group II, L/H ratio showed a significant correlation with stress and rest 201Tl perfusion defect size (r = 0. 39 and r = 0.42, P<0.01, respectively), but not with extent of ischaemic myocardium. The mean L/H ratio was 0.41+/-0.10 in patients with one-vessel disease (n = 15), 0.46+/-0.08 in those with two-vessel disease (n = 17) and 0.47+/-0.12 in those with three-vessel disease (n = 12), but no significant difference was found between the three subgroups. L/H ratio showed a significant inverse relation with rest and exercise left ventricular ejection fraction (r = -0.37 and r = -0.50, P<0.05 and P<0.001, respectively). Using stepwise multiple regression analysis, exercise left ventricular ejection fraction and previous history of hypertension were the sole two variables independently predictive of the L/H ratio. In conclusion, although lung thallium uptake is usually found to correlate with extent and severity of CAD, increased L/H ratio should primarily be considered as a marker of exercise-induced left ventricular systolic and perhaps diastolic dysfunction, probably independent of the underlying cardiac disease.

Prediction of human transplantation arteriopathy and coronary events with lung/heart count ratios during intravenous dipyridamole thallium-201 imaging

Background Cardiac allograft arteriopathy often limits long-term survival in transplantation recipients but has been difficult to detect by standard diagnostic methods. Because of the diffuse nature of transplantation coronary disease, we postulated that a lung/heart ratio during dipyridamole thallium imaging might better predict arteriopathy-related complications than diagnostic methods that detect discrete luminal stenoses. Methods and Results Sixty-six unselected heart transplantation recipients were evaluated with annual coronary arteriograms, endomyocardial biopsy, and intravenous dipyridamole thallium testing (initial study group). The mean lung/heart ratio on an anterior planar image was 0.40 for all patients; therefore <0.40 was arbitrarily defined as normal. After October 1992, 98 patients were tested (validation study group) and a lung/heart ratio cutoff of 0.40 was evaluated prospectively. Coronary end points were defined as (1) at least 1 coronary artery stenosis ≥50% of the luminal diameter, (2) sudden cardiac death, and (3) acute myocardial infarction. Stepwise logistic regression analysis was performed to identify independent predictors of future coronary end points. For the initial study group, the lung/heart ratio on the first annual thallium study was the only independent predictor of subsequent cardiac end points (0.47 ± 0.13 [SD] with end points vs 0.38 ± 0.11 without end points, P < .05). For the validation study group, independent predictors of subsequent coronary events included the lung/heart ratio and the radionuclide left ventricular ejection fraction. No patient with a lung/heart ratio <0.40 and a left ventricular ejection fraction ≥0.50 developed a cardiac event during 21 ± 11 months of follow-up. Conclusions A lung/heart ratio ≥0.40 on dipyridamole thallium testing is a sensitive predictor of coronary events after heart transplantation. Patients with heart transplantion who have a lung/heart ratio <0.40 and normal systolic left ventricular function are at low risk for subsequent coronary events and may not require annual surveillance by coronary arteriography. (Am Heart J 1999;137:942-8.)

Normal variants of a photon-deficient area in the lower sternum demonstrated by bone SPECT.

A highly variable normal appearance of the sternal area makes interpretation difficult on planar bone imaging. These normal variants occur especially in the area above the xiphoid process of the sternum in which an oval photopenic area on anterior planar images may be seen. This finding is most likely caused by localized incomplete fusion. Of a group of 188 patients, 35 patients (33 men, 2 women; age range, 30 to 85 years; mean age, 57 years) were examined with sternal SPECT and planar bone imaging. These patients, who had no history of sternal trauma, surgery, radiation, or infection, were referred for bone scan for metastatic work-up (n = 20), back pain (n = 6), and other conditions (n = 9). Thus 11 of 35 (31%) patients had a SPECT study that showed a photopenic area in the lower sternum. The incidence of this normal variant was higher than the 2% to 7.7% previously reported, indicating improved detection by SPECT. The normal variant appears to be less apparent on planar bone images and is seen more clearly on SPECT images. Differentiation from malignancy appears to be related to lesion symmetry, location, midline, and evenly distributed radioactivity surrounding the edge of the photopenic area.

Effects of smoking on pulmonary uptake of technetium-99m methoxyisobutyiisonitrile during myocardial perfusion imaging

Background. To determine the influence of smoking on 99mTc-labeled methoxyisobutylisonitrile ( 99mTc-MIBI) lung uptake during myocardial perfusion imaging, we examined 60 subjects with normal myocardial perfusion scans, normal coronary angiograms, and no evidence of left ventricular hypertrophy. Methods and Results. The subjects were divided into 2 groups: Group 1 subjects had smoking histories of at least 10 pack-years and Group 2 subjects were nonsmokers. 99mTc-MIBI lung to heart ratios (L/H ratios) from anterior planar images were obtained for all subjects during exercise and resting states. 99mTc-MIBI L/H ratios in smokers were significantly higher than in nonsmokers in both exercise and resting states. However, no significant difference in L/H ratios was found between exercise and resting states in smokers and nonsmokers. In addition, no significant correlation was found between smoking pack-years and either rest or exercise L/H ratios. Conclusions. 99mTc-MIBI L/H ratios in smokers are higher than in nonsmokers. This must be considered when 99mTc-MIBI L/H ratios are used clinically

Effect of exercise-induced activation of sympathetic nerve activity on clearance of 123I-MIBG from the myocardium.

The effect of exercise on the cardiac kinetics of 123I-MIBG was investigated in the present study. 123I-MIBG was administered intravenously at rest in 6 healthy male volunteers, and anterior planar and SPECT images were obtained 15 minutes, and 2 and 4 hours after administration (protocol A). After 4 weeks, 123I-MIBG was again administered intravenously at rest, and images were obtained 15 minutes later. After imaging, the subjects ran 10 km in approximately 1 hour, and anterior planar and SPECT images were obtained 2 and 4 hours after administration of 123I-MIBG (protocol B). The heart-to-mediastinum uptake ratio (H/M) was calculated from each anterior planar image, and the mean 123I-MIBG clearance from 15 minutes to 2 hours, and from 2 hours to 4 hours was calculated with a bull's eye display. The H/M was much lower after exercise. The mean clearance rate between 15 minutes and 2 hours in protocol B was significantly higher than that between 2 hours and 4 hours, and that between 15 minutes and 2 hours in protocol A. It was concluded that the clearance rate of 123I-MIBG may be a useful index of cardiac sympathetic nerve activity.

Double-phase Tc-99m sestamibi scintigraphy in the preoperative location of lesions causing hyperparathyroidism.

Hyperparathyroidism (HPT) is one of the most prevalent endocrine diseases, for which the only effective treatment is surgery. The use of imaging techniques in the preoperative localization of the hyperfunctioning glands is the subject of controversy. The purpose of this paper is to assess the use of double-phase scintigraphy with Tc-99m sestamibi in the localization of lesions causing HPT. We used scintigraphy to preoperatively examine 41 patients, 31 of whom had primary HPT and 10 with secondary HPT. We acquired two anterior view planar images of the neck and chest 10 minutes and 3 hours after injection of Tc-99m sestamibi. Final diagnosis, determined with biopsy, was adenoma in 26 patients, 24 of whom had a positive scintigraphic study (sensitivity 92%), with only two false negative results. In the 14 cases of parathyroid hyperplasia, scintigraphy was also positive, and 62% (30/48) of the excised glands were identified by Tc-99m sestamibi. The radioisotope study was of particular interest in the six patients who previously had undergone surgery, since all the studies were positive; in two patients, additional diseased glands were located in the neck, and an ectopic adenoma was found in the remaining four patients. A fifth ectopic lesion was also sestamibi-positive and, in this case, the scintigraphic result was a direct indication for mediastinal surgery. There were no false positive results, even in patients with multinodular goiter. We conclude that, due to its high sensitivity and the ease with which it is performed, double-phase scintigraphy with Tc-99m sestamibi is the preferred technique for the preoperative localization of diseased glands in patients with HPT, especially in cases of parathyroid adenoma, including those with aberrant location. Its use is of particular interest in patients who previously have undergone surgery.