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Fulltext Wiener filter improves diagnostic accuracy of CAD SPECT images-comparison to angiography and CT angiography

Masoomi MA, Al-Shammeri I, Kalafallah K, Elrahman HMA, Ragab O, Ahmed E, et al.

Medicine (Baltimore), 2019 Jan;98(4):e14207.
PMID: 30681596 DOI: 10.1097/MD.0000000000014207

Many discrepancy in selection of proper filter and its parameters for individual cases exists. The authors investigate the impact of the most common filters on patient NM images with coronary artery disease (CAD), and compare the results with the computerized tomography (CT)-Angio and angiography for accuracy.The investigation initiated by performing various single photon emission computerized tomography (SPECT)/CT scan of the national electrical manufacturers association chest phantoms having hot and cold inserts. Data acquired on GE 670 PRO SPECT/CT; 360Ø, 64 frames, 60 seconds, low energy high resolution (LEHR) 128, low energy general purpose (LEGP) with CT attenuation (120 kV and 170 mA). The images reconstructed with filtered back projection and ITERATIVE ordered-subset expectation maximization utilizing filters; Hann, Butterworth, Metz, Hamming, and Wiener. The Image contrast was calculated to assess absolute nearness of the inserts. Based on the preliminary results, then scans of 92 patients with CAD; 64 males and 28 females, age 41 to 77 years old, who had been reported earlier reprocessed with the nominated filter and were reported by 2 NM expert. The results compared to the earlier reports and to the CT-Angio and angiography.The optimization suggested 3 filters; Wiener (Wi), Metz and Butterworth (But) provide the highest contrast (99- 66.4%) and (81- 32%) for the cold and hot inserts respectively, with the (Wi) filter to be the better option. The reprocessed patients scan with the (Wi) presented an elevated diagnostic accuracy, correlated well with the CT-Angio and angiography results (P

Matched MeSH terms: Tomography, Emission-Computed, Single-Photon/instrumentation*; Tomography, Emission-Computed, Single-Photon/methods
Medical imaging modalities using nanoprobes for cancer diagnosis: A literature review on recent findings

Shahbazi-Gahrouei D, Moradi Khaniabadi P, Moradi Khaniabadi B, Shahbazi-Gahrouei S

J Res Med Sci, 2019;24:38.
PMID: 31143239 DOI: 10.4103/jrms.JRMS_437_18

Medical imaging modalities are used for different types of cancer detection and diagnosis. Recently, there have been a lot of studies on developing novel nanoparticles as new medical imaging contrast agents for the early detection of cancer. The aim of this review article is to categorize the medical imaging modalities accompanying with using nanoparticles to improve potential imaging for cancer detection and hence valuable therapy in the future. Nowadays, nanoparticles are becoming potentially transformative tools for cancer detection for a wide range of imaging modalities, including computed tomography (CT), magnetic resonance imaging, single photon emission CT, positron emission tomography, ultrasound, and optical imaging. The study results seen in the recent literature provided and discussed the diagnostic performance of imaging modalities for cancer detections and their future directions. With knowledge of the correlation between the application of nanoparticles and medical imaging modalities and with the development of targeted contrast agents or nanoprobes, they may provide better cancer diagnosis in the future.

Matched MeSH terms: Tomography, Emission-Computed, Single-Photon
Diagnosis of pulmonary embolism: A comparison between ventilation/perfusion SPECT/CT and perfusion-only SPECT/CT

Thanuja M, Maimanah M, Sara U

Med J Malaysia, 2020 09;75(5):490-493.
PMID: 32918415

BACKGROUND: The role of nuclear medicine in diagnosing pulmonary embolism (PE) is continuously evolving owing to advancements in imaging methods. In recent years, ventilation/perfusion single photon emission computed tomography-computed tomography (V/Q SPECT/CT) has established a synergistic role over conventional V/Q planar scintigraphy and V/Q SPECT in diagnosing pulmonary embolism.
OBJECTIVES: In this study, we aimed to assess the incremental value of V/Q SPECT/CT over conventional V/Q planar scintigraphy and V/Q SPECT, and to determine if Q only-SPECT/CT without the conventional ventilation component could replace the current imaging protocol in diagnosing pulmonary embolism.
METHODS: We retrospectively assessed 73 patients with suspicion of pulmonary embolism who had undergone/Q planar scintigraphy, V/Q SPECT and V/Q SPECT/CT consecutively. Combination of clinical follow-up, laboratory test results and correlative imaging were used as reference standard. Q-only SPECT/CT datasets were then analysed separately without the V-planar, V-SPECT and V-SPECT/CT datasets.
RESULTS: A total of 66 patients fulfilled our initial inclusion and exclusion criteria, with 23 patients as positive for PE and 43 patients ruled out of having PE based on the reference standard. Sensitivity and specificity for V/P planar scintigraphy, V/Q SPECT, and V/Q SPECT-CT were 86.9% and 39.5%, 91.3% and 55.8%, and 100% and 97.6% respectively. Overall, SPECT/CT resulted in significantly higher diagnostic accuracy than planar and SPECT imaging respectively (p<0.05). Q-only SPECT/CT significantly over diagnosed pulmonary embolism in 12 patients (p<0.05).
CONCLUSION: Adding V/Q SPECT/CT to the algorithm of PE significantly improves the sensitivity and specificity. However, by eliminating the ventilation component, the diagnostic accuracy is significantly reduced.

Matched MeSH terms: Tomography, Emission-Computed, Single-Photon/methods*
Fulltext Standardized Uptake Value from Semiquantitative Bone Single-Photon Emission Computed Tomography/Computed Tomography in Normal Thoracic and Lumbar Vertebrae of Breast Cancer Patients

Rohani MFM, Yonan SNM, Tagiling N, Zainon WMNW, Udin Y, Nawi NM

Asian Spine J, 2020 Oct;14(5):629-638.
PMID: 32213791 DOI: 10.31616/asj.2019.0308

STUDY DESIGN: Retrospective study.
PURPOSE: This study aims to semiquantitatively evaluate the standardized uptake value (SUV) of 99mTc-methylene diphosphonate (MDP) radionuclide tracer in the normal vertebrae of breast cancer patients using an integrated single-photon emission computed tomography (SPECT)/computed tomography (CT) scanner.
OVERVIEW OF LITERATURE: Molecular imaging techniques using gamma cameras and stand-alone SPECT have traditionally been utilized to evaluate metastatic bone diseases. However, these methods lack quantitative analysis capabilities, impeding accurate uptake characterization.
METHODS: A total of 30 randomly selected female breast cancer patients were enrolled in this study. The SUV mean (SUVmean) and SUV maximum (SUVmax) values for 286 normal vertebrae at the thoracic and lumbar levels were calculated based on the patients' body weight (BW), body surface area (BSA), and lean body mass (LBM). Additionally, 106 degenerative joint disease (DJD) lesions of the spine were also characterized, and both their BW SUVmean and SUVmax values were obtained. A receiver operating characteristic (ROC) curve analysis was then performed to determine the cutoff value of SUV for differentiating DJD from normal vertebrae.
RESULTS: The mean±standard deviations for the SUVmean and SUVmax in the normal vertebrae displayed a relatively wide variability: 3.92±0.27 and 6.51±0.72 for BW, 1.05±0.07 and 1.75±0.17 for BSA, and 2.70±0.19 and 4.50±0.44 for LBM, respectively. Generally, the SUVmean had a lower coefficient of variation than the SUVmax. For DJD, the mean±standard deviation for the BW SUVmean and SUVmax was 5.26±3.24 and 7.50±4.34, respectively. Based on the ROC curve, no optimal cutoff value was found to differentiate DJD from normal vertebrae.
CONCLUSIONS: In this study, the SUV of 99mTc-MDP was successfully determined using SPECT/CT. This research provides an approach that could potentially aid in the clinical quantification of radionuclide uptake in normal vertebrae for the management of breast cancer patients.

Matched MeSH terms: Tomography, Emission-Computed, Single-Photon
Fulltext Comparison of Low-Pass Filters for SPECT Imaging

Sayed IS, Ismail SS

Int J Biomed Imaging, 2020;2020:9239753.
PMID: 32308670 DOI: 10.1155/2020/9239753

In single photon emission computed tomography (SPECT) imaging, the choice of a suitable filter and its parameters for noise reduction purposes is a big challenge. Adverse effects on image quality arise if an improper filter is selected. Filtered back projection (FBP) is the most popular technique for image reconstruction in SPECT. With this technique, different types of reconstruction filters are used, such as the Butterworth and the Hamming. In this study, the effects on the quality of reconstructed images of the Butterworth filter were compared with the ones of the Hamming filter. A Philips ADAC forte gamma camera was used. A low-energy, high-resolution collimator was installed on the gamma camera. SPECT data were acquired by scanning a phantom with an insert composed of hot and cold regions. A Technetium-99m radioactive solution was homogenously mixed into the phantom. Furthermore, a symmetrical energy window (20%) centered at 140 keV was adjusted. Images were reconstructed by the FBP method. Various cutoff frequency values, namely, 0.35, 0.40, 0.45, and 0.50 cycles/cm, were selected for both filters, whereas for the Butterworth filter, the order was set at 7. Images of hot and cold regions were analyzed in terms of detectability, contrast, and signal-to-noise ratio (SNR). The findings of our study indicate that the Butterworth filter was able to expose more hot and cold regions in reconstructed images. In addition, higher contrast values were recorded, as compared to the Hamming filter. However, with the Butterworth filter, the decrease in SNR for both types of regions with the increase in cutoff frequency as compared to the Hamming filter was obtained. Overall, the Butterworth filter under investigation provided superior results than the Hamming filter. Effects of both filters on the quality of hot and cold region images varied with the change in cutoff frequency.

Matched MeSH terms: Tomography, Emission-Computed, Single-Photon
Accuracy Assessment of SUV Measurements in SPECT/CT: A Phantom Study

Halim F, Yahya H, Jaafar KN, Mansor S

J Nucl Med Technol, 2021 Sep;49(3):250-255.
PMID: 33722927 DOI: 10.2967/jnmt.120.259168

Advances in iterative image reconstruction enable absolute quantification of SPECT/CT studies by incorporating compensations for collimator-detector response, attenuation, and scatter. This study aimed to assess the quantitative accuracy of SPECT/CT based on different levels of 99mTc activity (low/high) using different SUV metrics (SUVmean, SUVmax, SUV0.6 max, and SUV0.75 max [the average values that include pixels greater than 60% and 75% of the SUVmax in the volume of interest, respectively]). Methods: A Jaszczak phantom equipped with 6 fillable spheres was set up with low and high activity ratios of 1:4 and 1:10 (background-to-sphere) on background activities of 10 and 60 kBq/mL, respectively. The fixed-size volume of interest based on the diameter of each sphere was drawn on SPECT images using various metrics for SUV quantification purposes. Results: The convergence of activity concentration was dependent on the number of iterations and application of postfiltering. For the background-to-sphere ratio of 1:10 with a low background activity concentration, the SUVmean metric showed an underestimation of about 38% from the actual SUV, and SUVmax exhibited an overestimation of about 24% for the largest sphere diameter. Meanwhile, bias reductions of as much as -6% and -7% for SUV0.6 max and SUV0.75 max, respectively, were observed. SUVmax gave a more accurate reading than the others, although points that exceeded the actual value were detected. At 1:4 and 1:10 background activity of 10 kBq/mL, a low activity concentration attained a value close to the actual ratio. Use of 2 iterations and 10 subsets without postfiltering gave the most accurate values for reconstruction and the best image overall. Conclusion: SUVmax is the best metric in a high- or low-contrast-ratio phantom with at least 2 iterations, 10 subsets, and no postfiltering.

Matched MeSH terms: Tomography, Emission-Computed, Single-Photon*
Operational nuclear research reactors in the Asia-Pacific with potential for medical radionuclide production

Tan HY, Wong YH, Kasbollah A, Md Shah MN, Perkins AC, Yeong CH

Nucl Med Commun, 2023 Apr 01;44(4):227-243.
PMID: 36808108 DOI: 10.1097/MNM.0000000000001665

Personalised cancer treatment is of growing importance and can be achieved via targeted radionuclide therapy. Radionuclides with theranostic properties are proving to be clinically effective and are widely used because diagnostic imaging and therapy can be accomplished using a single formulation that avoids additional procedures and unnecessary radiation burden to the patient. For diagnostic imaging, single photon emission computed tomography (SPECT) or positron emission tomography (PET) is used to obtain functional information noninvasively by detecting the gamma (γ) rays emitted from the radionuclide. For therapeutics, high linear energy transfer (LET) radiations such as alpha (α), beta (β - ) or Auger electrons are used to kill cancerous cells in close proximity, whereas sparing the normal tissues surrounding the malignant tumour cells. One of the most important factors that lead to the sustainable development of nuclear medicine is the availability of functional radiopharmaceuticals. Nuclear research reactors play a vital role in the production of medical radionuclides for incorporation into clinical radiopharmaceuticals. The disruption of medical radionuclide supplies in recent years has highlighted the importance of ongoing research reactor operation. This article reviews the current status of operational nuclear research reactors in the Asia-Pacific region that have the potential for medical radionuclide production. It also discusses the different types of nuclear research reactors, their operating power, and the effects of thermal neutron flux in producing desirable radionuclides with high specific activity for clinical applications.

Matched MeSH terms: Tomography, Emission-Computed, Single-Photon