Does quantification have a role to play in the future of bone SPECT?

Quantitative bone single photon emission computed tomography/computed tomography in symptomatic and asymptomatic foot and ankle osteoarthritis

PURPOSE

The purpose of this study was to evaluate and quantify the prevalence of increased uptake in SPECT/CT in symptomatic and asymptomatic foot and ankle joints in patients with osteoarthritis.

METHODS

In 63 patients with osteoarthritis (OA), the painful symptomatic foot (SF) and asymptomatic contralateral foot (AF) were imaged with bone SPECT/CT. Presence, localization, and maximum standardized uptake value (SUV max ) of the active joints were assessed for SF and AF. CT OA grade (grade 1: mild, grade 2: moderate, grade 3: severe) and presence of five morphological features of OA (joint space narrowing, subchondral sclerosis, subchondral cysts, irregular joint margins, and osteophytes) were evaluated.

RESULTS

In total 32 (51%) patients showed additional uptake in the AF, whereas 31 (49%) patients showed it only in the SF. SF showed more active joints than AF (106 vs. 43). CT OA grades positively correlated with SUV max (Kendall's tau b = 0.62, P  < 0.001). SUV max values (per foot) in SF were higher in patients with uptake in bilateral feet (SF+, AF+) [median (IQR): 17.9 (10.7-23.3)] as compared with patients with active sites only in the SF (SF+, AF-) [10.4 (6.4-19.1); P  < 0.001]. Number of active OA joints in SF was higher in patients with bilateral uptake ( P  = 0.017).

CONCLUSION

In conclusion, half of the patients exhibited increased uptake in the contralateral asymptomatic foot. SUV max showed a significant correlation to CT osteoarthritis grade, in the symptomatic and asymptomatic foot. Future follow-up studies will provide further insights into the prognostic and therapeutic value of these findings.

Whole-Body SPECT/CT: Protocol Variation and Technical Consideration-A Narrative Review

Introducing a hybrid imaging approach, such as single-photon emission computerized tomography with X-ray computed tomography (SPECT)/CT, improves diagnostic accuracy and patient management. The ongoing advancement of SPECT hardware and software has resulted in the clinical application of novel approaches. For example, whole-body SPECT/CT (WB-SPECT/CT) studies cover multiple consecutive bed positions, similar to positron emission tomography-computed tomography (PET/CT). WB-SPECT/CT proves to be a helpful tool for evaluating bone metastases (BM), reducing equivocal findings, and enhancing user confidence, displaying effective performance in contrast to planar bone scintigraphy (PBS). Consequently, it is increasingly utilized and might substitute PBS, which leads to new questions and issues concerning the acquisition protocol, patient imaging time, and workflow process. Therefore, this review highlights various aspects of WB-SPECT/CT acquisition protocols that need to be considered to help understand WB-SPECT/CT workflow processes and optimize imaging protocols.

Technological Advances in SPECT and SPECT/CT Imaging

Single photon emission tomography/computed tomography (SPECT/CT) is a mature imaging technology with a dynamic role in the diagnosis and monitoring of a wide array of diseases. This paper reviews the technological advances, clinical impact, and future directions of SPECT and SPECT/CT imaging. The focus of this review is on signal amplifier devices, detector materials, camera head and collimator designs, image reconstruction techniques, and quantitative methods. Bulky photomultiplier tubes (PMTs) are being replaced by position-sensitive PMTs (PSPMTs), avalanche photodiodes (APDs), and silicon PMs to achieve higher detection efficiency and improved energy resolution and spatial resolution. Most recently, new SPECT cameras have been designed for cardiac imaging. The new design involves using specialised collimators in conjunction with conventional sodium iodide detectors (NaI(Tl)) or an L-shaped camera head, which utilises semiconductor detector materials such as CdZnTe (CZT: cadmium-zinc-telluride). The clinical benefits of the new design include shorter scanning times, improved image quality, enhanced patient comfort, reduced claustrophobic effects, and decreased overall size, particularly in specialised clinical centres. These noticeable improvements are also attributed to the implementation of resolution-recovery iterative reconstructions. Immense efforts have been made to establish SPECT and SPECT/CT imaging as quantitative tools by incorporating camera-specific modelling. Moreover, this review includes clinical examples in oncology, neurology, cardiology, musculoskeletal, and infection, demonstrating the impact of these advancements on clinical practice in radiology and molecular imaging departments.

Quantitative vs. Qualitative SPECT-CT Diagnostic Accuracy in Bone Lesion Evaluation-A Review of the Literature

(1) Background: Considering the importance that quantitative molecular imaging has gained and the need for objective and reproducible image interpretation, the aim of the present review is to emphasize the benefits of performing a quantitative interpretation of single photon emission computed tomography-computed tomography (SPECT-CT) studies compared to qualitative interpretation methods in bone lesion evaluations while suggesting new directions for research on this topic. (2) Methods: By conducting comprehensive literature research, we performed an analysis of published data regarding the use of quantitative and qualitative SPECT-CT in the evaluation of bone metastases. (3) Results: Several studies have evaluated the diagnostic accuracy of quantitative and qualitative SPECT-CT in differentiating between benign and metastatic bone lesions. We collected the sensitivity and specificity for both quantitative and qualitative SPECT-CT; their values ranged between 74-92% and 81-93% for quantitative bone SPECT-CT and between 60-100% and 41-100% for qualitative bone SPECT-CT. (4) Conclusions: Both qualitative and quantitative SPECT-CT present an increased potential for better differentiating between benign and metastatic bone lesions, with the latter offering additional objective information, thus increasing diagnostic accuracy and enabling the possibility of performing treatment response evaluation through accurate measurements.

The role of serial 99mTc-DPD scintigraphy in monitoring cardiac transthyretin amyloidosis

PURPOSE

Cardiac transthyretin amyloidosis is a usually fatal form of restrictive cardiomyopathy for which clinical trials of treatments are ongoing. It is anticipated that quantitative nuclear medicine scintigraphy, which is experiencing growing interest, will soon be used to evaluate treatment efficacy. We investigated its utility for monitoring changes in disease load over a significant time period.

METHODS

Sixty-two treatment-naive patients underwent ^99mTc-labelled 3,3-diphosphono-1,2propanodicarboxylic acid (^99mTc-DPD) scintigraphy two to four times each over a five-year period. Quantitation of cardiac ^99mTc-DPD retention was performed according to two established methods: measurement of heart-to-contralateral ratio (H/CL) in the anterior view (planar) and percentage of administered activity in the myocardium (SPECT).

RESULTS

In total 170 datasets were analysed. Increased myocardial retention of ^99mTc-DPD was demonstrable as early as 12 months from baseline. Year-on-year progression across the cohort was observed using SPECT-based quantitation, though on 30 occasions (27.8%) the change in our estimate was negative.

CONCLUSIONS

The spread of our results was notably high compared to the year-on-year increases. If left unaccounted for, variance may draw fallacious conclusions about changes in disease load. We therefore urge caution in drawing conclusions solely from nuclear medicine scintigraphy on a patient-by-patient basis, particularly across a short time period.

Optimization of cross-calibration factor for quantitative bone SPECT without attenuation and scatter correction in the lumbar spine: head-to-head comparison with attenuation and scatter correction

OBJECTIVES

Quantitative single-photon emission computed tomography (SPECT) with computed tomography (SPECT/CT) is known to improve diagnostic performance. Although SPECT-alone systems are used widely, accurate quantitative SPECT using these systems is challenging. This study aimed to improve the accuracy of quantitative bone SPECT of the lumbar spine with the SPECT-alone system.

METHODS

The cross-calibration factor (CCF) was measured using three kinds of phantoms and the optimal values were determined. The recovery coefficient with and without attenuation and scatter correction (ACSC) were compared. Bone SPECT/CT was performed on 93 consecutive patients with prostate cancer, and the standardized uptake values (SUVs) were compared using the respective CCFs. The first 60 patients were classified according to body weight, and the correlation coefficient between SUVs with and without ACSC were calculated; the slopes were defined as body weight-based coefficients (BWCs). In the remaining 33 patients, the SUV was adjusted according to BWC, and the accuracy of the adjustment was verified.

RESULTS

The quantitative SPECT values obtained from the CCF using SIM2 bone phantom showed nearly accurate radioactivity concentrations, even without ACSC. The recovery coefficients with and without ACSC were similar. Unadjusted SUVs with and without ACSC were strongly correlated; however, SUVs without ACSC were significantly higher than those with ACSC (P < 0.0001). The mean difference between the SUVs with and without ACSC disappeared when the SUVs without ACSC were adjusted by BWC (P = 0.9814).

CONCLUSIONS

Our cross-calibration method for quantitative bone SPECT enables interpretation with a harmonized SUV even in SPECT-alone systems.

Quantitative evaluation of single-photon emission computed tomography findings in lower extremity possible without computed tomography-based attenuation correction

OBJECTIVE

For performing accurate quantitative analysis of single-photon emission computed tomography (SPECT)/computed tomography (CT) images, CT-based attenuation correction (CTAC) is considered to be necessary. However, the effect on quantitative values for an examined area close to the body surface, such as in the lower extremity, has yet to be elucidated. We performed the present investigation to determine the possibility of quantitative evaluation using a SPECT standalone device without CT.

METHODS

Validation was performed using clinical data of patients who underwent a lower extremity SPECT/CT examination, with grouping based on presence or absence of CTAC, scatter correction and resolution recovery. Using a reference group in which all types of correction were applied, standardized uptake values (SUVs), including maximum (SUVmax) and peak (SUVpeak), were examined in each group and compared.

RESULTS

As compared to the reference group, the difference in quantitative values became smaller in the order of the applied scatter correction and resolution recovery, applied resolution recovery, applied scatter correction, and neither scatter correction or resolution recovery applied groups, with no significant difference between the reference group and that with neither scatter correction or resolution recovery applied. A similar tendency was seen for both SUVmax and SUVpeak.

CONCLUSIONS

In bone SPECT quantitative examinations of the lower extremity, quantitative evaluation without CTAC is possible without the use of scatter correction or resolution recovery. Thus, quantitative evaluation can be performed with use of a standalone SPECT device without CT.

An alternative method for radioactivity measurement in quantitative bone SPECT/CT imaging

Bone scintigraphy with combined single-photon emission computed tomography (SPECT) and computed tomography (CT) has become widely used for the detection of bone metastases. However, calculation of the semi-quantitative standardized uptake value (SUV) requires measurement of the pre- and post-injection radioactivity of the radiopharmaceutical. This study aimed to compare measured and fixed input radioactivity values for quantitative SPECT/CT bone imaging to examine whether the fixed measurement method of radiopharmaceutical radioactivity could be used as an alternative method. Four different methods were used to quantify the Tc-99m hydroxymethylene diphosphonate input radioactivity: (A) measured pre- and post-injection radioactivity values; (B) measured pre-injection and fixed post-injection radioactivity values; (C) fixed pre-injection and measured post-injection radioactivity values; (D) fixed pre- and post-injection radioactivity values. All SPECT/CT acquisitions were analyzed using bone SPECT analysis software, and the semi-quantitative parameters (SUVpeak and SUVmean) were recorded and compared for each analytical method. Two semi-quantitative parameters showed significant differences between analytical methods A and B, A and D, and C and D. However, an additional subgroup analysis performed on patients whose median post-injection measured radioactivity value was <1.5 MBq showed no significant differences in parameters between all analytical methods. Measurement of the radiopharmaceutical radioactivity can be an alternative method because it reduces the volume of radioactivity post-injection. The simplified fixed measurement method of radiopharmaceutical radioactivity can be used as an alternative method in cases when measuring the radioactivity in quantitative bone SPECT/CT imaging is missed.

The relationship between the quantitative evaluation of thyroid bed uptake and the disappearance of accumulation in adjuvant radioactive iodine therapy for differentiated thyroid cancer

OBJECTIVE

Iodine-131 (I-131) radioactive iodine therapy (RAI) after total thyroidectomy is the standard treatment for patients with differentiated thyroid cancer (DTC). We investigated the relationship between the quantitative parameters of the iodine uptake and the disappearance of the accumulation in the thyroid bed in adjuvant therapy using a 1.11 GBq or 3.70 GBq dose of I-131.

METHODS

We retrospectively analyzed the cases of 40 patients with DTC who were treated with RAI at our institution between April 2017 and August 2019. The patients were treated with the I-131 dose of 1.11 GBq (n = 25) or 3.70 GBq (n = 15) after total thyroidectomy. The I-131 whole-body scan and hybrid single-photon emission computed tomography/X-ray computed tomography (SPECT/CT) were performed 3 days after RAI. Using image analysis software, we measured the standardized uptake value (SUV) and absolute radioactivity concentration (kBq/ml) on the target lesions with the highest uptake in the thyroid bed.

RESULTS

The median period from RAI to the evaluation of the absence of uptake of the thyroid bed was 6.75 months. After RAI, uptake of the thyroid bed disappeared in 26 of the 40 patients. The disappearance rate was significantly higher in the 3.70 GBq group than in the 1.11 GBq group (86.7% vs. 52.0%, respectively; p = 0.029). However, there were no significant differences in the values of kBq/ml or SUV between the 1.11 GBq group and 3.70 GBq group. On the other hand, the group in which the uptake disappeared after RAI showed significantly higher kBq/ml max and kBq/ml mean values than the group in which the uptake did not disappear after RAI (p = 0.028, p = 0.032, respectively). The SUVmax and SUVmean also tended to be higher in the disappeared-uptake group than the not-disappeared-uptake group, but the differences were not significant (p = 0.166, p = 0.176, respectively).

CONCLUSIONS

The quantitative evaluation might be useful as one of the predictive indicators of the disappearance of the accumulation of radioactive iodine in the thyroid bed.

Standardized Uptake Value from Semiquantitative Bone Single-Photon Emission Computed Tomography/Computed Tomography in Normal Thoracic and Lumbar Vertebrae of Breast Cancer Patients

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.

Phantom and clinical evaluation of bone SPECT/CT image reconstruction with xSPECT algorithm

BACKGROUND

Two novel methods of image reconstruction, xSPECT Quant (xQ) and xSPECT Bone (xB), that use an ordered subset conjugate gradient minimizer (OSCGM) for SPECT/CT reconstruction have been proposed. The present study compares the performance characteristics of xQ, xB, and conventional Flash3D (F3D) reconstruction using images derived from phantoms and patients.

METHODS

A custom-designed body phantom for bone SPECT was scanned using a Symbia Intevo (Siemens Healthineers), and reconstructed xSPECT images were evaluated. The phantom experiments proceeded twice with different activity concentrations and sphere sizes. A phantom with 28-mm spheres containing a 99mTc-background and tumor-to-normal bone ratios (TBR) of 1, 2, 4, and 10 were generated, and convergence property against various TBR was evaluated across 96 iterations. A phantom with four spheres (13-, 17-, 22-, and 28-mm diameters), containing a 99mTc-background at TBR4, was also generated. The full width at half maximum of an imaged spinous process (10 mm), coefficients of variance (CV), contrast-to-noise ratio (CNR), and recovery coefficients (RC) were evaluated after reconstructing images of a spine using Flash 3D (F3D), xQ, and xB. We retrospectively analyzed images from 20 patients with suspected bone metastases (male, n = 13) which were acquired using [99mTc]Tc-(H)MDP SPECT/CT, then CV and standardized uptake values (SUV) at the 4th vertebral body (L4) were compared after xQ and xB reconstruction in a clinical setup.

RESULTS

Mean activity concentrations with various TBR converged according to increasing numbers of iterations. The spatial resolution of xB was considerably superior to xQ and F3D, and it approached almost the actual size regardless of the iteration numbers during reconstruction. The CV and RC were better for xQ and xB than for F3D. The CNR peaked at 24 iterations for xQ and 48 iterations for F3D and xB, respectively. The RC between xQ and xB significantly differed at lower numbers of iterations but were almost equivalent at higher numbers of iterations. The reconstructed xQ and xB images of the clinical patients showed a significant difference in the SUVmax and SUVpeak.

CONCLUSIONS

The reconstructed xQ and xB images were more accurate than those reconstructed conventionally using F3D. The xB for bone SPECT imaging offered essentially unchanged spatial resolution even when the numbers of iterations did not converge. The xB reconstruction further enhanced SPECT image quality using CT data. Our findings provide important information for understanding the performance characteristics of the novel xQ and xB algorithms.

Quantification evaluation of 99mTc-MDP concentration in the lumbar spine with SPECT/CT: compare with bone mineral density

BACKGROUND

Despite recent technological advances allowing for quantitative single-photon emission computed tomography (SPECT), quantitative SPECT has not been widely used in the clinical practice of osteoporosis. The aim of this study is to evaluate the feasibility of quantitative bone SPECT/CT for measuring lumbar standard uptake value (SUV) in patients with different bone-mineral density (BMD), and investigate the correlation between SUV measured with ^99mTc-methylene diphosphonate (MDP) SPECT/CT and BMD assessment by dual-energy X-ray absorptiometry (DXA).

METHODS

A retrospective analysis of 62 cases ^99mTc-MDP whole-body bone imaging and local lumbar SPECT/CT tomography were performed. According to the results of dual-energy X-ray bone density examination, they were divided into normal group, osteopenic group, and osteoporosis group. The raw SPECT data were reconstructed using flash3D which includes attenuation correction, scatter compensation, and collimator resolution recovery, SPECT images from this algorithm were calibrated for SUV analysis. Comparing difference of lumbar SUV in different BMD subjects, and investigating the correlation between lumbar SUV and BMD. Data were analyzed by one-way ANOVA and Pearson regression analysis using SPSS 17.0 software.

RESULTS

The maximum SUV (SUV_max) and mean SUV (SUV_mean) of L1-L4 vertebral in 62 subjects were 7.39 ± 1.84 and 4.90 ± 1.27, respectively. The average BMD was 0.85 ± 0.15 (g/cm²), and the average CT value was 145.88 ± 53.99 (HU). The SUV_max, SUV_mean, BMD, and CT values of the lumbar spine were statistically significantly different among the three groups (F = 24.089, 30.501, 94.847, 30.241, all p < 0.001), and the osteopenic group was significantly lower than the normal group (all p < 0.001), the osteoporosis group was significantly lower than the normal group and the osteopenic group (all p < 0.001). Lumbar SUV_max, SUV_mean, and BMD were significantly negatively correlated with age (r = - 0.328 to - 0.442, all p < 0.05), and positively correlated with body weight and CT value (r = 0.299-0.737, all p < 0.05), but no significant correlation with height (r = 0.006-0.175, all p > 0.05). Lumbar SUV_max and SUV_mean increased significantly with the increase of BMD (r = 0.638, 0.632, p < 0.001).

CONCLUSION

The SUV of lumbar spine in ^99mTc-MDP bone SPECT/CT was significantly different among subjects with different BMD, and the SUV was positively correlated with BMD. These findings justify that quantitative bone SPECT/CT is an applicable tool for clinical quantification of bone metabolism in osteoporosis patients.