Single-photon emission computed tomography/computed tomography (SPECT/CT) is an already established nuclear imaging modality. Co-registration of functional information (SPECT) with anatomical images (CT) paved the way to the wider application of SPECT. Recent advancements in quantitative SPECT/CT have made it possible to incorporate quantitative parameters, such as standardized uptake value (SUV) or %injected dose (%ID), in gamma camera imaging. This is indeed a paradigm shift in gamma camera imaging from qualitative to quantitative evaluation. In fact, such quantitative approaches of nuclear imaging have only been accomplished for positron emission tomography (PET) technology. Attenuation correction, scatter correction, and resolution recovery are the three main features that enabled quantitative SPECT/CT. Further technical improvements are being achieved for partial-volume correction, motion correction, and dead-time correction. The reported clinical applications for quantitative SPECT/CT are mainly related to Tc-99m-labeled radiopharmaceuticals: Tc-99m diphosphonate for bone/joint diseases, Tc-99m pertechnetate for thyroid function, and Tc-99m diethylenetriaminepentaacetic acid for measurement of glomerular filtration rate. Dosimetry before trans-arterial radio-embolization is also a promising application for Tc-99m macro-aggregated albumin. In this review, clinical applications of Tc-99m quantitative SPECT/CT will be discussed.
Evaluation Studies as Topic ; Gamma Cameras ; Glomerular Filtration Rate ; Positron-Emission Tomography ; Radionuclide Imaging ; Radiopharmaceuticals ; Sodium Pertechnetate Tc 99m ; Thyroid Gland ; Tomography, Emission-Computed, Single-Photon

PURPOSE: The treatment efficiency of ⁹⁰Y and providing reliable estimates of activity are evaluated by SPECT imaging of bremsstrahlung radiation released during beta therapy. In this technique, the resulting spectrum from ⁹⁰Y is very complex and continuous, which creates difficulties on the imaging protocol. Moreover, collimator geometry has an impressive effect on the spatial resolution, system sensitivity, image contrast, and the signal-to-noise ratio (SNR), which should be optimized.METHODS: We evaluated the effect of energy window width, reconstruction algorithms, and different geometries of a medium-energy (ME) parallel-hole collimator on the image contrast and SNR of ⁹⁰Y SPECT images. The Siemens E.Cam gamma camera equipped with a ME collimator and a digital Jaszczak phantom were simulated by SIMIND Monte Carlo program to generate the ⁹⁰Y bremsstrahlung SPECT images.RESULTS: Our results showed that optimal image quality can be acquired by the reconstruction algorithm of OS-EM in the energy window width of 60 to 400 keV for ⁹⁰Y bremsstrahlung SPECT imaging. Furthermore, the optimal values of the hole diameter and hole length of a ME collimator were obtained 0.235 and 4.4 cm, respectively.CONCLUSIONS: The acquired optimal ME collimator and energy window along with using a suitable reconstruction algorithm lead to improved contrast and SNR of ⁹⁰Y bremsstrahlung images of hot spheres of the digital Jaszczak phantom. This can improve the accuracy and precision of the ⁹⁰Y activity distribution estimation after radioembolization in targeted radionuclide therapy.
Gamma Cameras ; Signal-To-Noise Ratio ; Tomography, Emission-Computed, Single-Photon

PURPOSE: This study aims to compare Monte Carlo-based codes' characteristics in the determination of the basic parameters of a high-resolution single photon emission computed tomography (HiReSPECT) scanner.METHODS: The geometry of this dual-head gamma camera equipped with a pixelated CsI(Na) scintillator and lead hexagonal hole collimator were accurately described in the GEANT4 Application for the Tomographic Emission (GATE), Monte Carlo N-particle extended (MCNP-X), and simulation of imaging nuclear detectors (SIMIND) codes.We implemented simulation procedures similar to the experimental test for calculation of the energy spectra, spatial resolution, and sensitivity of HiReSPECT by using 99mTc sources.RESULTS: The energy resolutions simulated by SIMIND, MCNP-X, and GATE were 17.53, 19.24, and 18.26%, respectively, while it was calculated at 19.15% in experimental test. The average spatial resolutions of the HiReSPECT camera at 2.5 cm from the collimator surface simulated by SIMIND, MCNP-X, and GATE were 3.18, 2.9, and 2.62 mm, respectively, while this parameter was reported at 2.82 mm in the experiment test. The sensitivities simulated by SIMIND, MCNP-X, and GATE were 1.44, 1.27, and 1.38 cps/µCi, respectively, on the collimator surface.CONCLUSIONS: Comparison between simulation and experimental results showed that among these MC codes, GATE enabled to accurately model realistic SPECT system and electromagnetic physical processes, but it required more time and hardware facilities to run simulations. SIMIND was the most flexible and user-friendly code to simulate a SPECT camera, but it had limitations in defining the non-conventional imaging device. The most important characteristics like time and speed of simulation, preciseness of results, and user-friendliness should be considered during simulations.
Animals ; Gamma Cameras ; Magnets ; Physical Processes ; Tomography, Emission-Computed, Single-Photon

PURPOSE: Sialolithiasis is one of the most prevalent large obstructive disorders of the submandibular glands. The aim of this study was to investigate submandibular sialolithiasis with computed tomography (CT) and scintigraphy, with a particular focus on the relationship between CT values of the submandibular glands and their excretion rate. MATERIALS AND METHODS: Fifteen patients with submandibular sialolithiasis who underwent CT and salivary gland scintigraphy were included in this study. The relationship between the CT values of submandibular glands with and without sialoliths and salivary gland excretion measured using salivary gland scintigraphy was statistically analyzed. Dynamic images were recorded on the computer at 1 frame per 20 seconds. The salivary gland excretion fraction was defined as A (before stimulation test [counts/frame]) / B(after stimulation test [counts/frame]) using time-activity curves. RESULTS: The CT values in the submandibular glands with and without sialoliths was 9.9±44.9 Hounsfield units (HU) and 34.2±21.8 HU, respectively (P=.233). Regarding the salivary gland excretion fraction using scintigraphy, the A/B value in the submandibular glands with sialoliths (1.09±0.23) was significantly lower than in the submandibular glands without sialoliths (1.99±0.57, P=.000). CONCLUSION: Assessments of the CT values and the salivary gland excretion fraction using scintigraphy in the submandibular glands seem to be useful tools evaluating submandibular sialolithiasis.
Gamma Cameras ; Humans ; Multidetector Computed Tomography ; Radionuclide Imaging* ; Salivary Duct Calculi ; Salivary Gland Calculi* ; Salivary Glands* ; Submandibular Gland*

The first step to nuclear medicine in Korea started with introduction of the gamma camera in 1969. Although planar images with the gamma camera give important functional information, they have the limitations that result from 2-dimensional images. Single-photon emission computed tomography (SPECT) due to its 3-dimensional image acquisition is superior to earlier planar gamma imaging in image resolution and diagnostic accuracy. As demand for a hybrid functional and anatomical imaging device has increased, integrated SPECT/CT systems have been used. In Korea, SPECT/CT was for the first time installed in 2003. SPECT/CT can eliminate many possible pitfalls on SPECT-alone images, making better attenuation correction and thereby improving image quality. Therefore, SPECT/CT is clinically preferred in many hospitals in various aspects.More recently, additional SPECT/CT images taken from the region with equivocal uptake on planar images have been helpful in making precise interpretation as part of their clinical workup in postoperative thyroid cancer patients. SPECT and SPECT/CT have various advantages, but its clinical application has gradually decreased in recent few years. While some researchers investigated the myocardial blood flow with cardiac PET using F-18 FDG or N-13 ammonia, myocardial perfusion SPECT is, at present, the radionuclide imaging study of choice for the risk stratification and guiding therapy in the coronary artery disease patients in Korea. New diagnostic radiopharmaceuticals for AD have received increasing attention; nevertheless, brain SPECT will remain the most reliable modality evaluating cerebral perfusion.
Ammonia ; Brain ; Coronary Artery Disease ; Gamma Cameras ; Humans ; Korea ; Nuclear Medicine ; Perfusion ; Radionuclide Imaging ; Radiopharmaceuticals ; Thyroid Neoplasms ; Tomography, Emission-Computed ; Tomography, Emission-Computed, Single-Photon

Breast-Specific Gamma Imaging (BSGI) is an improved and optimizing nuclear medicine breast imaging technique on the basis of traditional gamma camera. It uses a high resolution, small field-of-view scintilla detector. The detector is designed with 3 073 individual detector crystals and 48 position-sensitive photomultiplier tubes. The FOV of detector is 15 cm x 20 cm, and optimal system resolution for breast imaging is 3 mm, can detect the diameter of only 2-3 mm small lesions. BSGI has better sensitivity in detecting subcentimetre or nonpalpable breast cancer. The sensitivity for the diagnosis of breast cancer is high, not influenced by the density of the breast tissue, implants, architectural distortion-or scars from prior surgery or radiation. So it is called a high resolution, small field-of-view breast-specific gamma camera.
Breast ; Breast Neoplasms ; diagnosis ; Diagnostic Imaging ; Female ; Gamma Cameras ; Humans

BACKGROUND/AIMS: Lack of simple and repeatable tests hampers gastric emptying studies in rats. The aim of this study was to adapt the 14C-octanoate solid gastric emptying breath test for application in rats, and to validate it against radioscintigraphic method. METHODS: After ingestion of a meal containing 3 mCi 99mTc and 2 microCi 14C-octanoate, 23 male Wistar rats were placed on a gamma camera in a airflow container. Scintigraphic images were taken at regular intervals. The amount of 14CO2 in a regularly replaced hyamine hydroxide solution, capturing CO2 in the outflow air, was counted using liquid scintillation spectrometry. 99mTc gastric retention curves and 14CO2-excretion curves were fitted to their respective data. Three rats underwent the same procedures after administration of atropine. RESULTS: Overall Tr10% (time at which 10% of the original amount of 99mTc remained in the stomach) was 355 +/- 64 minutes; Te90% (time at which 90% of total amount of 14CO2 was excreted) was 325 +/- 106 minutes. Their correlation coefficient was 0.71, R-square 0.50 and P < 0.005. Tr1/2 (50% of original amount of 99mTc remained) was 124 +/- 28 minutes; Te1/2 (50% of total amount of 14CO2 excreted) 114 +/- 32 minutes. Their correlation coefficient was 0.83 with R-square of 0.69 and P < 0.00005. In 12 immobilized animals correlation was even better: correlation coefficient 0.84; R-square 0.71 and P < 0.001 (Tr10% was 388 +/- 117 minutes; Te90% 532 +/- 219 minutes; Tr1/2 of 165 +/- 54 minutes; Te1/2 of 175 +/- 67 minutes). Atropine significantly lengthened all emptying times: 904 +/- 307 and 1461 +/- 684 minutes for Tr10% and Te90%, respectively; and 432 +/- 117 minutes for Tr1/2 and 473 +/- 190 minutes for Te1/2. CONCLUSIONS: We adapted and validated the 14C-octanoate gastric emptying breath test for application in rats.
Animals ; Atropine ; Benzethonium ; Breath Tests ; Caprylates ; Eating ; Gamma Cameras ; Gastric Emptying ; Humans ; Hydroxides ; Male ; Meals ; Rats ; Rats, Wistar ; Retention (Psychology) ; Spectrum Analysis

PURPOSE: We wanted to assess the clinical efficacy of breast-specific gamma imaging (BSGI) as compared with that of conventional imaging modalities (mammography, ultrasonography and magnetic resonance imaging) as a preoperative examination for patients with breast cancer. METHODS: From April to May 2009, a retrospective review was performed for the prospectively collected 143 patients who were diagnosed with breast cancer. All the patients received a conventional imaging examination and BSGI before definitive surgery. The patients underwent BSGI with intravenous injection of 30 mCi of (99m)Tc-sestamibi through the contralateral antecubital vein. After 10 minutes, the craniocaudal and mediolateral oblique images were obtained. All the imaging findings were correlated with the final pathologic examination. RESULTS: The mean age of the patients was 49.7+/-9.4 years (range, 27-77). In 143 patients, 166 malignant lesions were identified by pathologic examination (invasive cancer: 96 (67.1%), ductal carcinoma in situ 14 (9.8%) and invasive cancer with carcinoma in situ 33 (23.1%). The conventional imaging modalities found 166 malignant lesions and BSGI found 156 malignant lesions. The rate of correspondence was 94.0% between the conventional imaging modalities and BSGI for malignant lesions. For BSGI, there were 4 false positive findings and 10 false negative findings. BSGI found no occult cancers that were missed by conventional imaging modality. For making the diagnosis of axillary lymph node metastasis, the sensitivity, specificity and accuracy were 33.3%, 92.1%, and 69.9% for BSGI, and 55.6%, 77.5%, and 69.2%, for ultrasonography, respectively. CONCLUSION: BSGI may have the potentiality to make a correct diagnosis in breast cancer patients. However, in this study, it seems that BSGI is not superior to conventional imaging modalities. BSGI is not a standard method to evaluate breast cancer lesions before surgery.
Breast ; Breast Neoplasms ; Carcinoma in Situ ; Carcinoma, Intraductal, Noninfiltrating ; Gamma Cameras ; Humans ; Injections, Intravenous ; Lymph Nodes ; Magnetic Resonance Spectroscopy ; Neoplasm Metastasis ; Prospective Studies ; Retrospective Studies ; Sensitivity and Specificity ; Technetium Tc 99m Sestamibi ; Veins

PURPOSE: We aimed to prove the relative limitation of 99mTc-DMSA scintigraphy (DMSA) compared to computed tomography (CT) in diagnosing acute pyelonephritis (APN) in children. METHODS: Since September 2006, after a 64-channel CT was imported, 10 DMSA false-negative patients have been identified: these patients underwent a CT scan for acute abdomen or acute febrile symptoms and were diagnosed as having APN; however, their DMSA scans were clear. We focused on these 10 DMSA false-negative patients and analyzed their clinical findings and CT results. We used Philips Brilliance Power 64-channel CT scanner for the CT scan and Siemens Orbitor Nuclear Camera 60 Hz for the DMSA scan. RESULTS: The 10 DMSA false-negative patients were mostly males (80%) and infants (80%). They had fever for a mean of 1.1-day duration before admission and showed increase in acute reactants: leukocyte, erythrocyte sedimentation rate, and C-reactive protein. The CT findings of renal lesions were focal in 6 (60%) cases and diffuse in 4 (40%) cases, and most of the lesions were unilateral in 80% of patients. CT proved that 22 renal lesions were neglected by DMSA. Differential renal function test by DMSA was also of no use in the evaluation of renal lesions. CONCLUSION: In this study, DMSA scan showed limitation in finding renal cortical lesions of CT-proven APN patients. DMSA false-negative results seem to occur at early-phase disease of infantile age, but more prospective studies are needed to determine the reasons and their prevalence.
Abdomen, Acute ; Blood Sedimentation ; C-Reactive Protein ; Child ; Fever ; Gamma Cameras ; Humans ; Infant ; Leukocytes ; Male ; Prevalence ; Pyelonephritis ; Succimer ; Technetium Tc 99m Dimercaptosuccinic Acid

PURPOSE: We assessed the absorbed dose to the tumor (Dosetumor) by using pretreatment FDG-PET and whole-body (WB) planar images in repeated radioimmunotherapy (RIT) with 131I rituximab for NHL. MATERIALS AND METHODS: Patients with NHL (n=4) were administered a therapeutic dose of (131)I rituximab. Serial WB planar images after RIT were acquired and overlaid to the coronal maximum intensity projection (MIP) PET image before RIT. On registered MIP PET and WB planar images, 2D-ROIs were drawn on the region of tumor (n=7) and left medial thigh as background, and Dosetumor was calculated. The correlation between Dosetumor and the CT-based tumor volume change after RIT was analyzed. The differences of Dosetumor and the tumor volume change according to the number of RIT were also assessed. RESULTS: The values of absorbed dose were 397.7+/-646.2cGy (53.0~2853.0cGy). The values of CT-based tumor volume were 11.3+/-9.1 cc (2.9~34.2cc), and the % changes of tumor volume before and after RIT were -29.8+/-44.3% (-100.0%~+42.5%), respectively. Dosetumor and the tumor volume change did not show the linear relationship (p>0.05). Dosetumor and the tumor volume change did not correlate with the number of repeated administration (p>0.05). CONCLUSION: We could determine the position and contour of viable tumor by MIP PET image. And, registration of PET and gamma camera images was possible to estimate the quantitative values of absorbed dose to tumor.
Antibodies, Monoclonal, Murine-Derived ; Gamma Cameras ; Humans ; Lymphoma ; Lymphoma, Non-Hodgkin ; Radioimmunotherapy ; Thigh ; Tumor Burden ; Rituximab