99mTc-MIBI Uptake Research Articles

Ultrastructure of Hyperfunctioning Parathyroid Glands: Does it Explain Various Patterns of 99mTc-sestamibi Uptake.

The aim of this study was to correlate the uptake of 99mTc-methoxy-isobutyl-isonitrile (MIBI) with ultra-structural features of parathyroid adenomas. Twenty patients with proven primary hyperparathyroidism were evaluated prospectively. Preoperative double-phase 99mTc-MIBI scintigraphy was performed in all patients and the degree of tracer uptake by the parathyroid lesions was assessed visually and semi-quantitatively. The excised glands were examined histologically and ultrastructurally, and their features were correlated with the degree of the radiotracer uptake. At surgery, 21 parathyroid adenomas were removed (double adenoma in one patient and a solitary adenoma in each of the remaining 19 patients). 99mTc-MIBI scan detected 18 of the 21 adenomas. There was positive correlation between the degree of 99mTc-MIBI uptake and the mitochondrial contents of the parathyroid adenoma cells. Four adenomas with intense uptake had high content of mitochondria in the cells. The three false-negative scans had low-to-moderate mitochondrial content. 99mTc-MIBI uptake is related to the mitochondrial content of the parathyroid adenoma cells.

РАДИОНУКЛИДНЫЕ МЕТОДЫ ИССЛЕДОВАНИЯ В ДИАГНОСТИКЕ РАКА ГОРТАНИ И ГОРТАНОГЛОТКИ

Introduction. The choice of adequate treatment for cancer patients and their survival rates signifcantly depend on the precise detection of the primary tumor and the assessment of the extent of cancer involvement. Despite advances in the treatment of laryngeal/hypopharyngeal cancer, many aspects of this problem are still unresolved. The purpose of the study. Diagnostic capabilities of nuclear medicine imaging in the detection and assessment of the spread of laryngeal/hypopharyngeal cancer were studied. Material and methods. The study included 40 patients with histologically verifed laryngeal/ hypopharyngeal cancer, 10 patients with tumor recurrence after completion of therapy and 20 patients with benign laryngeal lesions. Single photon emission computed tomography (SPECT) was performed 20 minutes after the injection of 99mTc-methoxy-isobutyl-isonitrile (MIBI). Sentinel lymph nodes (SLNs) were detected in 26 patients after submucosal injections of 99mTc-Tehneft or 99mTc-Alotech around the tumor. In 18 hours after the injection of 99mTc-Tehneft and 99mTc-Alotech, SPECT was performed. In 24 hours after the injection of 99mTc-Tehneft and 99mTc-Alotech, intraoperative SLN detection was performed using Gamma Finder II. Results. SPECT with 99mTc-MIBI revealed laryngeal and hypopharyngeal tumors in 38 of the 40 patients. The 99mTc-MIBI uptake in metastatic lymph nodes was visualized in 2 (17 %) of the 12 patients. 28 SLNs were detected by SPECT and 31 SLNs were identifed using the intraoperative gamma probe. The percentage of lymphotropic radiopharmaceuticals in the SLN was 5–10 % of the radioactivity in the injection site by SPECT and 12–33 % by intraoperative gamma probe detection. Conclusion. SPECT with 99mTc-MIBI is an effective tool for the diagnosis of laryngeal/hypopharyngeal cancer. The sensitivity, specifcity and accuracy of this technique were 95, 80 and 92 %, respectively. The use of 99mTc-Tehnefte and 99mTc-Alotech for the detection of SLN in laryngeal/hypopharyngeal cancer patients was characterized by high effcacy, while intraoperative detection was more sensitive, being 80 and 100 %, respectively.

Prevalence of Subclinical Peripheral Vascular Disease in Obese Egyptian Patients.

Objective:To detect subclinical peripheral vascular disease in obese Egyptian patients and establish relations between obesity, metabolic risk factors, and PVD.Methods:This was a prospective case-control study including 100 obese patients (BMI >30) (G1). In addition, 100 age and sex matched non-obese healthy subjects as a control group (G2). Both groups were subjected to duplex ultrasound, Radionuclide muscle scan. Angiography was done for 17 patients.Results:The image pattern of 99mTc-MIBI muscles uptake was studied and perfusion reserve (PR%) was calculated in (G1) and (G2). Comparison between the two groups showed statistically significant difference (P < 0.001) as regarding laboratory findings. Patients were categorized according to PR% into +ve for ischemia (mean PR% was 28.4 ± 20.3) and -ve for ischemia (mean PR% was 65.0 ± 11.4). Among (G1) 64 patients positive for ischemia by both PR% and Doppler, 36 patients were negative by Doppler and 22 of them were positive for ischemia by PR%. Angiography was done for 17 of them and proved ischemia in all of them.Conclusion:The Tc-99m sestamibi muscle scan can be used as a screening and diagnostic tool of preclinical atherosclerosis in obese patients.

Contribution of early SPECT/CT to 99mTc-MIBI double phase scintigraphy in primary hyperparathyroidism: Diagnostic value and correlation between uptake and biological parameters

AimTo evaluate the value of 99mTc-MIBI double-phase scintigraphy (DPS) and early SPECT/CT in the pre-surgical assessment of patients with primary hyperparathyroidism (PHPT). Also, to calculate the correlation between uptake and some biological parameters. Material and methodsForty patients with PHPT were included: 37 solitary adenomas, 1 hyperplasia, and 2 double adenomas. Fifteen patients had ectopic glands.DPS and early SPECT/CT were acquired in all patients. Ultrasound was performed in 31/40. All patients underwent surgery, intra-operative iPTH measurements, and histopathological examinations.Qualitative DPS uptake was assessed and correlated to pre-surgical calcium, iPTH levels, gland weight, and maximum diameter. ResultsIn the planar study, there were 23 positive cases, 8 doubtful, and 9 negatives. With the SPECT/CT, 8/9 negatives cases were located. All doubtful cases were confirmed as positives. Gland location improved in 16 cases (12 ectopic).DPS+SPECT/CT failed to detect a solitary adenoma and at least one gland in three cases of multiglandular disease (MGD). The sensitivity by patient was: DPS 72.5%, DPS+SPECT/CT 90%, and ultrasound 42%.Ultrasound and scintigraphy (DPS+SPECT/CT) were concordant in 16/31 patients. For the rest of them, scintigraphy proved correct in 14/15, and both techniques failed in one case.There was a significant correlation between level of uptake and iPTH level, gland weight, and maximum diameter. ConclusionEarly SPECT/CT improves sensitivity and the locating of parathyroid pathological glands and increases diagnostic confidence. iPTH level, glandular size, and weight are related to the qualitative assessment of 99mTc-MIBI uptake in early DPS.

Contribution of early SPECT/CT to 99mTc-MIBI double phase scintigraphy in primary hyperparathyroidism: Diagnostic value and correlation between uptake and biological parameters.

To evaluate the value of 99mTc-MIBI double-phase scintigraphy (DPS) and early SPECT/CT in the pre-surgical assessment of patients with primary hyperparathyroidism (PHPT). Also, to calculate the correlation between uptake and some biological parameters. Forty patients with PHPT were included: 37 solitary adenomas, 1 hyperplasia, and 2 double adenomas. Fifteen patients had ectopic glands. DPS and early SPECT/CT were acquired in all patients. Ultrasound was performed in 31/40. All patients underwent surgery, intra-operative iPTH measurements, and histopathological examinations. Qualitative DPS uptake was assessed and correlated to pre-surgical calcium, iPTH levels, gland weight, and maximum diameter. In the planar study, there were 23 positive cases, 8 doubtful, and 9 negatives. With the SPECT/CT, 8/9 negatives cases were located. All doubtful cases were confirmed as positives. Gland location improved in 16 cases (12 ectopic). DPS+SPECT/CT failed to detect a solitary adenoma and at least one gland in three cases of multiglandular disease (MGD). The sensitivity by patient was: DPS 72.5%, DPS+SPECT/CT 90%, and ultrasound 42%. Ultrasound and scintigraphy (DPS+SPECT/CT) were concordant in 16/31 patients. For the rest of them, scintigraphy proved correct in 14/15, and both techniques failed in one case. There was a significant correlation between level of uptake and iPTH level, gland weight, and maximum diameter. Early SPECT/CT improves sensitivity and the locating of parathyroid pathological glands and increases diagnostic confidence. iPTH level, glandular size, and weight are related to the qualitative assessment of 99mTc-MIBI uptake in early DPS.

Is Brown Adipose Tissue Visualization Reliable on 99mTc-Methoxyisobutylisonitrile Diagnostic SPECT Scintigraphy?

The 99mTc-MIBI has been used with great value as a diagnostic technique in patients with primary hyperparathyroidism. False-positive scans may occur due to misinterpretation of the physiologic distribution of the 99mTc-MIBI. Reviewing consecutive SPECT scans, we evaluated this possibility and assessed how frequently brown adipose tissue (BAT) is seen on 99mTc-MIBI scintigraphy.Here, we retrospectively reviewed scans of consecutive patients who were evaluated for parathyroid adenomas from March 2015 to June 2015, using dual-phase (early and delayed) planar imaging and SPECT. We identified 60 patients (48 female and 12 male; mean age, 52.25 ± 15.20 years; range, 22–86 years).We detected the presence of 99mTc-MIBI uptake in BAT in 20 of 60 patients (33.33%) in the neck. Although the patients with 99mTc-MIBI uptake in BAT were younger (mean age, 48.85 ± 15.27 years, range, 26–73 years) than the patients with no 99mTc-MIBI uptake (mean age, 53.95 ± 15.07 years, range, 22–86 years), this difference was not statistically significant (P = 0.224). The percentage of female patients with BAT detection was higher (17/48 patients; 37.5%) than that of the male population (3/12 patients; 25%), this difference was not also statistically significant (P = 0.85).In patient population referred to 99mTc MIBI scintigraphy of the parathyroid glands, uptake of 99mTc-MIBI in BAT should not be misinterpreted with 99mTc-MIBI-avid-tumors. Fused SPECT/CT images (not SPECT-only) are necessary to distinguish BAT from bone, muscle, thyroid, myocardium, parathyroids, and other structures in the neck and chest.

99mTc-MIBI Lung Scintigraphy in the Assessment of Pulmonary Involvement in Interstitial Lung Disease and Its Comparison With Pulmonary Function Tests and High-Resolution Computed Tomography: A Preliminary Study.

The differentiation of active inflammatory processes from an inactive form of the disease is of great value in the management of interstitial lung disease (ILD). The aim of this investigation was to assess the efficacy of 99mTc-methoxy-isobutyl-isonitrile (99mTc-MIBI) scans in distinguishing the severity of the disease compared to radiological and clinical parameters.In total, 19 known cases of ILD were included in this study and were followed up for 1 year. Five patients without lung disease were considered as the control group. The patients underwent pulmonary function tests (PFTs) and high-resolution computed tomography scans, followed by 99mTc-MIBI scanning. The 99mTc-MIBI scans were analyzed either qualitatively (subjectively) or semiquantitatively.All 19 ILD patients demonstrated a strong increase in 99mTc-MIBI uptake in the lungs compared to the control group. The 99mTc-MIBI scan scores were higher in the patient group in both the early phase (0.24[0.19–0.31] vs 0.11[0.10–0.15], P < 0.05) and the delayed phase (0.15[0.09–0.27] vs 0.04[0.01–0.09], P < 0.05) compared with the control group. A positive correlation was detected between the 99mTc-MIBI scan and the high-resolution computed tomography (HRCT) scores (Spearman's correlation coefficient = 0.65, P < 0.02) in the early phase but not in the delayed phase in patients (P > 0.14). The 99mTc-MIBI scan scores were not significantly correlated with the PFT findings (P > 0.05). In total, 5 patients died and 14 patients were still alive over the 1-year follow-up period. There was also a significant difference between the uptake intensity of 99mTc-MIBI and the outcome in the early phase (dead: 0.32[0.29–0.43] vs alive: 0.21[0.18–0.24], P < 0.05) and delayed phase (dead: 0.27[0.22–0.28] vs alive: 0.10[0.07–0.19], P < 0.05).The washout rate was ∼40 min starting from 20 min up to 60 min and this rate was significantly different in our 2 study groups (ILD: 46.61[15.61–50.39] vs NL: 70.91[27.09–116.36], P = 0.04).The present study demonstrated that 99mTc-MIBI lung scans might distinguish the severity of pulmonary involvement in early views, which were well correlated with HRCT findings. These results also revealed that 99mTc-MIBI lung scans might be used as a complement to other diagnostic and clinical examinations in terms of functional information in ILD; however, further investigations are strongly required.

99mTc-MIBI Scintigraphy to differentiate malignancies from benign lesions detected on Planar bone scans

The aim of study was to evaluate the effectiveness of 99mTc-MIBI (hexakis 2-methoxyisobutyl isonitrile) scintigraphy to differentiate malignant from benign lesions, detected on 99mTc-MDP planar bone scans. 59 patients with bony lesions were studied prospectively and compared with histopathology. Each patient underwent a 99mTc-MDP scan, and if evidence of lesion found, patient underwent 99mTc-MIBI scintigraphy after three to four days. 99mTc-MIBI scans were evaluated visually and quantitatively. For quantitative analysis count ratio of lesion to contralateral normal side (L/C) was taken and Student T test was applied.99mTc-MDP scans showed increase tracer uptake but no significant difference between benign and malignant uptake was seen. Significant difference (p value 0.015), was seen in malignant (L/C 3.51±1.02) and benign lesions (L/C 2.50±0.42) on 99mTc-MIBI scan. Three of thirty benign lesions did not show significant 99mTc-MIBI uptake. Six malignant lesions appeared as false negatives. Specificity of 99mTc-MIBI was 86.66%, Negative Predictive Value (NPV) 81.25% whereas the sensitivity was 79.31%.99mTc-MIBI scintigraphy provides its usefulness by distinguishing malignant from benign lesions along with correct identification of metastatic lesions. NPV points toward its ability to correctly diagnose the normal (benign) cases. However biopsy still remains the gold standard and a definitive diagnostic modality.

The effect of the time interval between the last breastfeeding and Tc-99m MIBI injection on the intensity of Tc-99m MIBI uptake in breast tissue

In this case report, we present a 36-year-old lactating woman, 10 months after delivery, who was referred to our clinic for a myocardial perfusion scintigraphy (MPS) due to chest pain. A scintigraphic procedure was performed according to the two-day protocol. On the first day, dipyridamole pharmacological stress Tc-99m MIBI MPS was performed, and on the second day, the same test was repeated while in a resting state without the administration of any pharmacological agent. The stress scan, compared to the rest scan, presented a higher uptake of Tc-99m MIBI in the breast tissue. The patient query revealed that the last breastfeeding was 12 hours before the stress scan and she did not breastfeed or express breast milk prior to the rest scan. Our findings suggest that ceasing the emptying of the mammary glands prior to the Tc-99m MIBI injection might be appropriate to decrease the radiation exposure of the mammary glands and the breast-fed baby.

Assessment of 99mTc-MIBI SPECT(/CT) to monitor multidrug resistance-related proteins and apoptosis-related proteins in patients with ovarian cancer: a preliminary study

Multidrug resistance (MDR) has been suggested to be a major cause of failure of chemotherapy treatment for cancer. It is associated with the expression of MDR-related and apoptosis-related proteins. Recently, technetium-99m hexakis 2-methoxyisobutylisonitrile ((99m)Tc-MIBI) has been suggested as a tumor-seeking agent for the detection of MDR. The aim of this study was to evaluate (99m)Tc-MIBI single-photon emission computed tomography (SPECT)(/CT) for functional imaging of MDR-related and apoptosis-related proteins in patients with ovarian cancer. Eleven women (mean age 63 years, range 53-76) with a clinical suspicion of ovarian cancer were prospectively studied. All patients were examined with (99m)Tc-MIBI imaging before surgery. After intravenous injection of 740 MBq (99m)Tc-MIBI, SPECT(/CT) imaging at 10 min and 2 h was performed. Based on the semiquantitative analysis of (99m)Tc-MIBI SPECT(/CT), both early and delayed tumor uptake ratios and washout rate % were calculated. The expression of MDR-related and apoptosis-related proteins was assessed in surgically excised tumors. Immunohistochemical staining was performed to quantify the expression levels of multidrug resistance protein 1 (MDR1), multidrug resistance-associated protein1 (MRP1), MRP3, lung resistance protein (LRP), breast cancer resistance protein (BCRP), Y-box-binding protein-1 (YB-1), Bcl-2, Bax and glutathione-S-transferase. (99m)Tc-MIBI imaging results and immunohistochemical results were compared. Laparotomy was performed in all patients. Six ovarian cancers were proven by histopathological examination. Five of the six ovarian cancers were positive for (99m)Tc-MIBI uptake on both early and delayed images with (99m)Tc-MIBI SPECT(/CT). MDR-related and apoptosis-related proteins were found to be expressed in all tumors. For the five positive (99m)Tc-MIBI uptake cases, the washout rate % of (99m)Tc-MIBI uptake showed a significant positive correlation with the expression of YB-1 (r = 0.988, P = 0.0015), and the early tumor uptake ratio showed a significant positive correlation with the expression of Bax (r = 0.882, P = 0.047). Our results suggested that (99m)Tc-MIBI SPECT(/CT) might be a valuable diagnostic imaging technique to evaluate MDR-associated YB-1 and Bax-mediated apoptosis in patients with ovarian cancer.

Development of 4D mathematical observer models for the task-based evaluation of gated myocardial perfusion SPECT

This paper presents two 4D mathematical observer models for the detection of motion defects in 4D gated medical images. Their performance was compared with results from human observers in detecting a regional motion abnormality in simulated 4D gated myocardial perfusion (MP) SPECT images. The first 4D mathematical observer model extends the conventional channelized Hotelling observer (CHO) based on a set of 2D spatial channels and the second is a proposed model that uses a set of 4D space-time channels. Simulated projection data were generated using the 4D NURBS-based cardiac-torso (NCAT) phantom with 16 gates/cardiac cycle. The activity distribution modelled uptake of 99mTc MIBI with normal perfusion and a regional wall motion defect. An analytical projector was used in the simulation and the filtered backprojection (FBP) algorithm was used in image reconstruction followed by spatial and temporal low-pass filtering with various cut-off frequencies. Then, we extracted 2D image slices from each time frame and reorganized them into a set of cine images. For the first model, we applied 2D spatial channels to the cine images and generated a set of feature vectors that were stacked for the images from different slices of the heart. The process was repeated for each of the 1,024 noise realizations, and CHO and receiver operating characteristics (ROC) analysis methodologies were applied to the ensemble of the feature vectors to compute areas under the ROC curves (AUCs). For the second model, a set of 4D space-time channels was developed and applied to the sets of cine images to produce space-time feature vectors to which the CHO methodology was applied. The AUC values of the second model showed better agreement (Spearman’s rank correlation (SRC) coefficient = 0.8) to human observer results than those from the first model (SRC coefficient = 0.4). The agreement with human observers indicates the proposed 4D mathematical observer model provides a good predictor of the performance of human observers in detecting regional motion defects in 4D gated MP SPECT images. The result supports the use of the observer model in the optimization and evaluation of 4D image reconstruction and compensation methods for improving the detection of motion abnormalities in 4D gated MP SPECT images.

Estimation of organ activity using four different methods of background correction in conjugate view method

To make an accurate estimation of the uptake of radioactivity in an organ using the conjugate view method, corrections of physical factors, such as background activity, scatter, and attenuation are needed. The aim of this study was to evaluate the accuracy of four different methods for background correction in activity quantification of the heart in myocardial perfusion scans. The organ activity was calculated using the conjugate view method. A number of 22 healthy volunteers were injected with 17-19 mCi of (99m)Tc-methoxy-isobutyl-isonitrile (MIBI) at rest or during exercise. Images were obtained by a dual-headed gamma camera. Four methods for background correction were applied: (1) Conventional correction (referred to as the Gates' method), (2) Buijs method, (3) BgdA subtraction, (4) BgdB subtraction. To evaluate the accuracy of these methods, the results of the calculations using the above-mentioned methods were compared with the reference results. The calculated uptake in the heart using conventional method, Buijs method, BgdA subtraction, and BgdB subtraction methods was 1.4 ± 0.7% (P < 0.05), 2.6 ± 0.6% (P < 0.05), 1.3 ± 0.5% (P < 0.05), and 0.8 ± 0.3% (P < 0.05) of injected dose (I.D) at rest and 1.8 ± 0.6% (P > 0.05), 3.1 ± 0.8% (P > 0.05), 1.9 ± 0.8% (P < 0.05), and 1.2 ± 0.5% (P < 0.05) of I.D, during exercise. The mean estimated myocardial uptake of (99m)Tc-MIBI was dependent on the correction method used. Comparison among the four different methods of background activity correction applied in this study showed that the Buijs method was the most suitable method for background correction in myocardial perfusion scan.

Axillary lymph node staging in breast cancer: clinical value of single photon emission computed tomography-computed tomography (SPECT-CT) with 99mTc-methoxyisobutylisonitrile

To determine diagnostic accuracy of SPECT, CT and SPECT-CT in axillary lymph node (LN) staging in breast cancer (BC). Sixty consecutive patients with primary operable T1-3NxM0 BC were included in this study. All patients underwent SPECT-CT examination on Symbia-T16 scanner which consists of dual-head gamma camera combined with 16 slices diagnostic CT. SPECT-CT acquisition started 10-15 min after i/v injection of 740-1,000 MBq of 99mTc-MIBI. On CT images of axillary LN we analyzed following diagnostic signs: size (short axis more or less than 10 mm), shape (round or oval), cortical thickness and fat content (solid or with fat gate). Intensity of tracer uptake in axillary LN was classified as follows: grade (Gr) I-background, Gr II-slightly above background, Gr III-intense but below uptake in muscles, Gr IV-as high as in muscles. Histological examination of dissected LN was used as gold standard. Various combinations of CT signs of axillary LN involvement demonstrated moderate diagnostic value with best results characterized by low (55 %) sensitivity (SEN), 97 % specificity (SP) and 83 % accuracy (AC). Intensive (Gr IV) uptake of 99mTc-MIBI in axillary LN characterized by low (55 %) SEN, high (100 %) SP and moderate (84 %) AC. Combination of CT and SPECT signs looks most promising especially when LN metastases were diagnosed in patients with enlarged solid LN or normal sized LN with Gr III-IV 99Tc-MIBI uptake. In these cases, SEN was equal to 75 %, SP-90 %, AC-85 %, only one of 5 patients with false negative results had metastases in more than 2 LN. By combination of SPECT and CT data we can more accurately diagnose axillary LN invasion by breast cancer.

Bone uptake of Tc-99m MIBI in patients with hyperparathyroidism

The study aimed to investigate the incidence of bone uptake of tracer on Tc-99m MIBI imaging and explore its influencing factors and significance for diagnosis of metabolic bone disease (MBD) in patients with hyperparathyroidism (HPT). Seventy-nine consecutive patients with histopathologically confirmed HPT (63 primary and 16 secondary) who had preoperative Tc-99m MIBI imaging were retrospectively evaluated. Serum calcium (Ca), phosphorus (P), and intact parathyroid hormone (iPTH) were measured for all patients, and serum alkaline phosphatase (ALP) was measured for 62 patients. Of the 79 patients, 50 underwent bone mineral density (BMD) examination and 30 underwent bone scintigraphy. The incidence and characteristics of abnormal bone uptake of MIBI were recorded. Mann-Whitney test was performed to determine if serum iPTH, Ca, P, ALP, and BMD were different between the patients with and without MIBI bone uptake. Logistic regression analysis was used to analyze the factors that influence the bone uptake of MIBI. The concordance rate between Tc-99m MIBI imaging and bone scintigraphy in delineating MBD was calculated. Tc-99m MIBI imaging disclosed the abnormal bone uptake of tracer in 22 (27.8 %) patients. Of them, 19 showed diffusely increased activity in skeleton, 2 showed focal uptake in brown tumors, and one showed both above patterns. Patients with bone uptake MIBI had higher level of serum iPTH (Z = -4.34, P < 0.001) and ALP (Z = -3.50, P < 0.001) than those without bone uptake. Logistic regression analysis also showed that bone uptake of MIBI was correlated with serum iPTH (OR = 4.42, P < 0.001) and ALP (OR = 3.21, P = 0.002). Among the 30 patients that underwent bone scintigraphy, 76.7 % patients showed signs of MBD, and the concordance rate between Tc-99m MIBI imaging and bone scintigraphy was 60 % for detecting MBD. Bone uptake of MIBI in patients with HPT is commonly related to a high level of iPTH and ALP; it probably reflects an active stage of MBD, and it should be monitored during the conventional Tc-99m MIBI scintigraphy.

Early assessment of high-intensity focused ultrasound treatment of benign thyroid nodules by scintigraphic means

BackgroundHigh-intensity focused ultrasound (HIFU) allows to inflict intracorporal thermal lesions without penetrating the skin or damaging the surrounding tissue. This analysis intends to assess the magnitude of HIFU-induced ablations within benign thyroid nodules using scintigraphic imaging with 99mTc.MethodsTen cold, hot, or indifferent nodules were treated using multiple pulses of HIFU to induce temperatures of around 85°C within the ablation zone. Pre- and posttreatment, uptake values of 99mTc-pertechnetate or 99mTc-MIBI were recorded. The pre-post reduction of nodular uptake was evaluated to assess ablation magnitude.ResultsRelative nodular uptake in relation to total thyroidal uptake decreased after one session of HIFU in all cases. Median 99mTc-MIBI uptake reduction was 35.5% (ranging from 11% to 57%; p < 0.1), while 99mTc-pertechnetate scintigraphy showed a median uptake reduction of 27% (range 10% to 44%; p < 0.1). No major complications were observed.ConclusionsHIFU appears to be safe and is an easy to perform means of thermal ablation. This study shows that HIFU treatment in thyroidal nodules can be evaluated by scintigraphic means shortly after the intervention. Due to small sample size, the exact magnitude of HIFU ablation efficiency in thyroidal nodules remains a value to be assessed in a larger study.

Advantages of Pinhole Collimator Double-Phase Scintigraphy With 99mTc-MIBI in Secondary Hyperparathyroidism

The aim of the study was to determine if pinhole collimator-acquired images can improve the detection of hyperfunctioning parathyroid glands in patients with secondary hyperparathyroidism. Forty-two patients being treated with cinacalcet for secondary hyperparathyroidism were studied prospectively. Patients were divided into 2 groups according to their levels of parathyroid hormone (PTH), the hormone that defines response to treatment: "responders" (PTH <300 pg/mL) and "nonresponders" (PTH ≥ 300 pg/mL). Double-phase scintigraphy using 888 MBq of (99m)Tc-MIBI was used to acquire early and late parallel-hole and pinhole collimator images. Neck ultrasonography was performed on all patients to identify intrathyroid nodules. All focal uptake in any of the acquired scintigraphic images was considered positive. The responder group included 24 patients, whereas 18 patients were considered as nonresponders. At least 1 parathyroid gland with (99m)Tc-MIBI uptake was detected in 33 of 42 patients, with a total of 50 parathyroid glands located. We found significant differences between the detection rates of late pinhole collimator and the late parallel-hole images (74% vs 48%, P = 0.0036). This detection rate was highest with late parallel-hole images in the nonresponder group (89%). The late pinhole collimator acquisition showed the highest detection rate of hyperfunctioning parathyroid glands using (99m)Tc-MIBI scintigraphy in secondary hyperparathyroidism patients treated with cinacalcet.

99mTc Sestamibi as a Prognostic Factor of Response to First-Line Therapy and Outcome in Patients With Malignant Lymphoma

Resistance to chemotherapy poses a major problem in cancer patients. Although of multifactorial origin, some of the implicated mechanisms also interfere with (99m)Tc-MIBI uptake and retention in cancer cells. The aim of the current study was to investigate the prognostic value of baseline (99m)Tc-MIBI imaging in lymphoma. (99m)Tc-MIBI SPECT was performed in 16 patients with Hodgkin lymphoma and 31 with non-Hodgkin lymphoma (NHL) before chemotherapy initiation. Early (20 minutes), late (120 minutes) tumor-to-background (T/B) ratios, and 2-hour (99m)Tc-MIBI washout were calculated. Follow-up data were obtained for a period of 45.5 ± 23.5 months. Study end points were response to first-line chemotherapy, lymphoma-related death (LRD), and time to disease progression. Of the scintigraphic indices examined, the late T/B ratio correlated best with study end points. A cutoff value of 1.8 determined by receiver operating characteristic analysis discriminated poor from good response and LRD from survival with an accuracy of 87% and 81%, respectively. Kaplan-Meier survivor functions separated by this cutoff differed significantly for both time to disease progression and LRD (P = 0.0001 and P = 0.0015). In the Cox proportional hazards model, the late T/B ratio proved to have an independent and incremental value over clinical prognostic factors (age, lymphoma type, Ann Arbor stage, lactate dehydrogenase levels) and, in NHL patients, over the international prognostic index. Patients with high international prognostic index score could be further stratified into different prognostic categories. The current study indicates that baseline (99m)Tc-MIBI SPECT can provide useful prognostic information in patients with lymphoma, particularly NHL, regarding therapy response and final outcome.

Quantification of Human and Rodent Brown Adipose Tissue Function Using99mTc-Methoxyisobutylisonitrile SPECT/CT and18F-FDG PET/CT

For brown adipose tissue (BAT) to be effective at consuming calories, its blood flow must increase enough to provide sufficient fuel to sustain energy expenditure and also transfer the heat created to avoid thermal injury. Here we used a combination of human and rodent models to assess changes in BAT blood flow and glucose utilization. (99m)Tc-methoxyisobutylisonitrile (MIBI) SPECT (n = 7) and SPECT/CT (n = 74) scans done in adult humans for parathyroid imaging were reviewed for uptake in regions consistent with human BAT. Site-directed biopsies of subcutaneous and deep neck fat were obtained for electron microscopy and gene expression profiling. In mice, tissue perfusion was measured with (99m)Tc-MIBI (n = 16) and glucose uptake with (18)F-FDG (n = 16). Animals were kept fasting overnight, anesthetized with pentobarbital, and given intraperitoneally either the β3-adrenergic receptor agonist CL-316,243, 1 mg/kg (n = 8), or saline (n = 8) followed by radiotracer injection 5 min later. After 120 min, the mice were imaged using SPECT/CT or PET/CT. Vital signs were recorded over 30 min during the imaging. BAT, white adipose tissue (WAT), muscle, liver, and heart were resected, and tissue uptake of both (99m)Tc-MIBI and (18)F-FDG was quantified by percentage injected dose per gram of tissue and normalized to total body weight. In 5.4% of patients (4/74), (99m)Tc-MIBI SPECT/CT showed increased retention in cervical and supraclavicular fat that displayed multilocular lipid droplets, dense capillary investment, and a high concentration of ovoid mitochondria. Expression levels of the tissue-specific uncoupling protein-1 were 180 times higher in BAT than in subcutaneous WAT (P < 0.001). In mice, BAT tissue perfusion increased by 61% (P < 0.01), with no significant changes in blood flow to WAT, muscle, heart, or liver. CL-316,243 increased glucose uptake in BAT even more, by 440% (P < 0.01). Pharmacologic activation of BAT requires increased blood flow to deliver glucose and oxygen for thermogenesis. However, the glucose consumption far exceeds the vascular response. These findings demonstrate that activated BAT increases glucose uptake beyond what might occur by increased blood flow alone and suggest that activated BAT likely uses glucose for nonthermogenic purposes.

Differentiation of tumor sensitivity to photodynamic therapy and early evaluation of treatment effect by nuclear medicine techniques

Our final goal is to develop an appropriate method using nuclear medicine technique for monitoring the effect and prediction of Photodynamic Therapy (PDT) on tumors. The aim of this study is to evaluate the effect of PDT on tumor cells in vitro using (18)F-FDG and (99m)Tc-MIBI as tracers. Five tumor cell lines (A431, DU145, H1650, LS180, SHIN3) with varied characteristics were irradiated after incubating for 24h with several doses of Photofrin (PF). Singlet oxygen was monitored by the near-IR emission detection system during irradiation and generated (1)O2 was calculated. PDT effects were rapidly evaluated by nuclear medicine techniques (uptake of (18)F-FDG and (99m)Tc-MIBI) and traditional methods for cell viability (MTT and trypan blue assays) at 3h after PDT. Intracellular PF concentration was measured by absorption spectrometer and cell protein content was measured by the Lowry method. (18)F-FDG uptake, (99m)Tc-MIBI uptake, singlet oxygen, and intracellular PF concentration were standardized by protein content. Decrease % of (18)F-FDG and (99m)Tc-MIBI, MTT, and trypan blue was normalized to the control group. Decrease % of (18)F-FDG was exponentially related to decrease % of MTT (R (2)=0.650, P<0.01) while decrease % of (99m)Tc-MIBI was linearly related to that of MTT (R (2)=0.719, P<0.01). The decrease % of MTT was more sensitive than that of trypan blue. However, neither (1)O2 nor PF uptake was correlated with sensitivity to PDT. In addition, (18)F-FDG uptake before PDT was linearly related to decrease % of MTT (R (2)=0.800, P<0.05). Our findings in in vitro studies suggest that (99m)Tc-MIBI is better than (18)F-FDG for early evaluation of PDT effect, but (18)F-FDG uptake may be used to predict PDT sensitivity before therapy.

Non-visualized Thyroid Gland by Tc-99m MIBI Scan with Normal Thyroid Scan.

We present the case of a 21-year-old man who was referred to us for parathyroid scintigraphy with high blood levels of intact parathormone and osteoporosis. Several methods and radiopharmaceuticals, e.g., Tc-99m MIBI and Tl-201 chloride/Tc-99m pertechnetate (Tl-201/TcPO−4) subtraction, are commonly used for this purpose. We present the case of a thyroid gland that demonstrates quite normal Tc-99m pertechnetate uptake, no accumulation of Tc-99m MIBI, and very low grade Tl-201 uptake. To the best of our knowledge, no similar case has been reported previously. A 21-year-old male with osteoporosis and growth-development retardation was referred for MIBI parathyroid scan because of high blood levels of intact parathormone and bone-specific alkaline-phosphatase, which were 219.4 (15–88 pg/ml) and 355 (21–58 U/L), respectively. In his Tc-99m pertechnetate (TcPO−4) pinhole scintigraphy, bilateral clearly visualized radioactivity accumulation in the thyroid gland was seen (Fig. 1a). In both early or late images of the Tc-99m MIBI parathyroid scan, the thyroid gland was not visualized (Fig. 1b). Therefore, a Tl-201/TcPO−4 subtraction scan method was used. However, the Tl-201 accumulation level in the thyroid gland was not sufficient for the subtraction method (Fig. 1c). In his thyroid ultrasonography, the thyroid gland echo was homogenous, and there was neither any solid nor cystic lesion. The physical examination of his neck was normal. Other laboratory findings were all normal as follows. TSH: 3.03 (0.35–5.6 IU/mL), free T3: 3.66 (2.5–3.9 pg/mL), free T4: 0.90 (0.59–1.3 ng/dL), Anti-TPO:0.3 (0–40 IU/mL), Anti-TG-Ab: <2.2 (0- + u/L), TSH receptor Ab: 1.0 (0–14 U/L), osteocalcine: 9.13 (1.5–15 ng/dL), growth hormone: 1.3 (0.014–5.21), calcitonin:17 (0–150 ng/mL), sedimentation:6 (0–15 mm/h). There were no significant symptoms of acute or chronic thyroiditis. The cause for discordant uptake in the thyroid gland with T1-201 and Tc-99m MIBI scan could not be provided through clinical or laboratory examinations. Parathyroid scan is a noninvasive method used in determining parathyroid adenoma, and Tc-99m MIBI and Tl-201/TcPO−4 subtraction methods are commonly applied [1–3]. The thyroid gland was not visualized on Tc-99m MIBI scintigraphy of suppressed thyroid tissue in a study by Turkolmez et al. [4]. It should be taken into account that sometimes we may not be able to visualize a normal thyroid gland, and in these cases we might encounter suboptimal visualization in T1-201 subtraction method as well. Erdil et al. found that Tl-201 is superior to Tc-99m MIBI in the visualization of suppressed thyroid tissue with a toxic thyroid nodule [5]. Kiratli et al. mentioned decreased uptake of Tc-99m MIBI in the thyroid gland in hemodialysis patients. However, no patient presented an absence of Tc-99m MIBI uptake in the thyroid gland with secondary hyperthyroidism [6]. In this case, the thyroid was not suppressed and the TcPO−4 scan thyroid gland was normal, but the thyroid gland was not visualized with Tc-99m MIBI parathyroid scan, and Tl-201 accumulation in the thyroid gland was not sufficient. To the best of our knowledge, from a search of the published literature, there has been no case like this previously reported. Fig. 1 Scintigraphy of a 21-year-old male with high blood levels of intact parathormone and osteoporosis. a Tc-99m pertechnetate (TcPO−4) pinhole scintigraphy shows bilateral accumulated radioactivity in the thyroid gland. b Thyroid gland is not visualized ...