Detection of prostate cancer bone metastases with fast whole-body 99mTc-HMDP SPECT/CT using a general-purpose CZT system.

BACKGROUND: We evaluated the effects of acquisition time, energy window width, and matrix size on the image quality, quantitation, and diagnostic performance of whole-body 99mTc-HMDP SPECT/CT in the primary metastasis staging of prostate cancer. METHODS: Thirty prostate cancer patients underwent 99mTc-HMDP SPECT/CT from the top of the head to the mid-thigh using a Discovery NM/CT 670 CZT system with list-mode acquisition, 50-min acquisition time, 15% energy window width, and 128 × 128 matrix size. The acquired list-mode data were resampled to produce data sets with shorter acquisition times of 41, 38, 32, 26, 20, and 16 min, narrower energy windows of 10, 8, 6, and 4%, and a larger matrix size of 256 × 256. Images were qualitatively evaluated by three experienced nuclear medicine physicians and quantitatively evaluated by noise, lesion contrast and SUV measurements. Diagnostic performance was evaluated from the readings of two experienced nuclear medicine physicians in terms of patient-, region-, and lesion-level sensitivity and specificity. RESULTS: The originally acquired images had the best qualitative image quality and lowest noise. However, the acquisition time could be reduced to 38 min, the energy window narrowed to 8%, and the matrix size increased to 256 × 256 with still acceptable qualitative image quality. Lesion contrast and SUVs were not affected by changes in acquisition parameters. Acquisition time reduction had no effect on the diagnostic performance, as sensitivity, specificity, accuracy, and area under the receiver-operating characteristic curve were not significantly different between the 50-min and reduced acquisition time images. The average patient-level sensitivities of the two readers were 88, 92, 100, and 96% for the 50-, 32-, 26-, and 16-min images, respectively, and the corresponding specificities were 78, 84, 84, and 78%. The average region-level sensitivities of the two readers were 55, 58, 59, and 56% for the 50-, 32-, 26-, and 16-min images, respectively, and the corresponding specificities were 95, 98, 96, and 95%. The number of equivocal lesions tended to increase as the acquisition time decreased. CONCLUSION: Whole-body 99mTc-HMDP SPECT/CT can be acquired using a general-purpose CZT system in less than 20 min without any loss in diagnostic performance in metastasis staging of high-risk prostate cancer patients.

A Prospective Comparison of 18F-prostate-specific Membrane Antigen-1007 Positron Emission Tomography Computed Tomography, Whole-body 1.5 T Magnetic Resonance Imaging with Diffusion-weighted Imaging, and Single-photon Emission Computed Tomography/Computed Tomography with Traditional Imaging in Primary Distant Metastasis Staging of Prostate Cancer (PROSTAGE).

BACKGROUND: Computed tomography (CT) and bone scintigraphy (BS) are the imaging modalities currently used for distant metastasis staging of prostate cancer (PCa). OBJECTIVE: To compare standard staging modalities with newer and potentially more accurate imaging modalities. DESIGN, SETTING, AND PARTICIPANTS: This prospective, single-centre trial (NCT03537391) enrolled 80 patients with newly diagnosed high-risk PCa (International Society of Urological Pathology grade group ≥3 and/or prostate-specific antigen [PSA] ≥20 and/or cT ≥ T3; March 2018-June 2019) to undergo primary metastasis staging with two standard and three advanced imaging modalities. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The participants underwent the following five imaging examinations within 2 wk of enrolment and without a prespecified sequence: BS, CT, 99mTc-hydroxymethylene diphosphonate (99mTc-HMDP) single-photon emission computed tomography (SPECT)-CT, 1.5 T whole-body magnetic resonance imaging (WBMRI) using diffusion-weighted imaging, and 18F-prostate-specific membrane antigen-1007 (18F-PSMA-1007) positron emission tomography(PET)-CT. Each modality was reviewed by two independent experts blinded to the results of the prior studies, who classified lesions as benign, equivocal, or malignant. Pessimistic and optimistic analyses were performed to resolve each equivocal diagnosis. The reference standard diagnosis was defined using all available information accrued during at least 12 mo of clinical follow-up. Patients with equivocal reference standard diagnoses underwent MRI and/or CT to search for the development of anatomical correspondence. PSMA PET-avid lesions without histopathological verification were rated to be malignant only if there was a corresponding anatomical finding suspicious for malignancy at the primary or follow-up imaging. RESULTS AND LIMITATIONS: Seventy-nine men underwent all imaging modalities except for one case of interrupted MRI. The median interval per patient between the first and the last imaging study was 8 d (interquartile range [IQR]: 6-9). The mean age was 70 yr (standard deviation: 7) and median PSA 12 ng/mL (IQR:7-23). The median follow-up was 435 d (IQR: 378-557). Metastatic disease was detected in 20 (25%) patients. The imaging modality 18F-PSMA-1007 PET-CT had superior sensitivity and highest inter-reader agreement. The area under the receiver-operating characteristic curve (AUC) values for bone metastasis detection with PSMA PET-CT were 0.90 (95% confidence interval [CI]: 0.85-0.95) and 0.91 (95% CI: 0.87-0.96) for readers 1 and 2, respectively, while the AUC values for BS, CT, SPECT-CT, and WBMRI were 0.71 (95% CI: 0.58-0.84) and 0.8 (95% CI: 0.67-0.92), 0.53 (95% CI: 0.39-0.67) and 0.66 (95% CI: 0.54-0.77), 0.77 (95% CI: 0.65-0.89) and 0.75 (95% CI: 0.62-0.88), and 0.85 (95% CI: 0.74-0.96) and 0.67 (95% CI: 0.54-0.80), respectively, for the other four pairs of readers. The imaging method 18F-PSMA-1007 PET-CT detected metastatic disease in 11/20 patients in whom standard imaging was negative and influenced clinical decision making in 14/79 (18%) patients. In 12/79 cases, false positive bone disease was reported only by PSMA PET-CT. Limitations included a nonrandomised study setting and few histopathologically validated suspicious lesions. CONCLUSIONS: Despite the risk of false positive bone lesions, 18F-PSMA-1007 PET-CT outperformed all other imaging methods studied for the detection of primary distant metastasis in high-risk PCa. PATIENT SUMMARY: In this report, we compared the diagnostic performance of conventional and advanced imaging. It was found that 18F-prostate-specific membrane antigen-1007 positron emission tomography/computed tomography (18F-PSMA-1007 PET-CT) was superior to the other imaging modalities studied for the detection of distant metastasis at the time of initial diagnosis of high-risk prostate cancer. PSMA PET-CT also appears to detect some nonmetastatic bone lesions.

Multicenter evaluation of renography with an automated physical phantom.

PURPOSE: The diversity of the dynamic radionuclide renal imaging (renography) study protocols sets challenges for the overall study quality, therefore raising a need for national quality control. The aim of this study was to encourage the standardization of renography in Finland and to evaluate the development after a previous study performed in 1997. METHODS: The new Heikkinen phantom was imaged in each of the 20 participating nuclear medicine laboratories. The results were interpreted in the manner of a regular patient study, and reconstructions and printouts were made according to the clinical routines of each laboratory. Four quantitative parameters were calculated and compared between laboratories. The reports were also assessed in a blind test. RESULTS: The average error in T(max) values ranged from -5 to 7% (-29 to +18% in 1997), in T(1/2) from 0 to 35% (-43 to +66%), in RCA20 from -20 to +28% (-50 to +82%) and in relative uptake from -3 to 5%. The difference from average in relative uptake ranged from -4 to 5% (-21 to +36%). CONCLUSION: The results showed that the errors in T(max) and relative uptake were generally within quite acceptable margins, and the variation in quantitative parameters between laboratories was shown to be smaller than 14 years earlier. The reason might be the use of new software packages as well as increased efforts to improve the quality of the studies.

Interdepartmental audit with an anatomically realistic lung phantom.

UNLABELLED: The diagnostic proficiency of nuclear medicine professionals and the accuracy of equipment may be tested with phantoms. All phases of the imaging chain should be included in the external quality assurance of imaging. METHODS: The aim of this study was to evaluate and compare the quality of nuclear imaging of the lung in Finland. For this purpose, we developed a new anatomically realistic lung phantom. The phantom consisted of plastic containers filled with plastic pellets to imitate the 3-dimensional shape of the lungs. These containers were filled with radioactive liquid and placed inside an anatomically accurate phantom of the chest cavity. The attenuation properties of the phantom were close to those of a real human thorax. Perfusion and ventilation defects were positioned inside the phantom to mimic 2 clinical cases. The phantom was imaged and interpreted as a patient simulation study in 18 Finnish hospitals. Reconstruction, printout, and reporting were according to the clinical routine of each hospital. The quality of the image sets and reports was evaluated and scored from 0 to 10. Additionally, technical performance was evaluated by a nuclear medicine specialist and hospital physicians. RESULTS: The average score (+/-SD) for overall quality was 7.1+/-1.1 (range, 5.2-8.5). Reports received a score of 7.2+/-1.7 (4.7-10.0); image sets, 7.2+/-1.3 (4.8-9.7), technical evaluation by hospital readers, 6.5+/-2.3 (1.6-9.5); and technical evaluation by a specialist, 7.8+/-1.2 (5.7-10.0). CONCLUSION: Lung imaging routines and the results of this survey were diverse. None of the participating hospitals routinely used tomography. In planar imaging, the most valuable projections were oblique (left anterior oblique, right anterior oblique, left posterior oblique, and right posterior oblique) and straight sides (right and left). The phantom mimics variable clinical situations well and is suitable for testing of imaging protocols and for proficiency testing of nuclear medicine professionals and equipment. Clinical phantom studies are an effective way of assessing an imaging program.