Nuclear Medicine Communications

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Diagnostic performance of PET/computed tomography versus PET/MRI and diffusion-weighted imaging in the N- and M-staging of breast cancer patients

imageObjective
To provide a systematic review regarding the diagnostic performance of 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/magnetic resonance imaging (PET/MRI) and diffusion-weighted imaging (DWI) compared to 18F-FDG PET/computed tomography (CT) focused on nodal and distant staging in breast cancer patients.
Methods
The PubMed and Embase databases were searched for relevant publications until April 2020. Two independent reviewers searched for eligible articles based on predefined in- and exclusion criteria, assessed quality and extracted data.
Results
Eleven eligible studies were selected from 561 publications identified by the search. In seven studies, PET/CT was compared with PET/MRI, and in five, PET/CT with DWI. Significantly higher sensitivity for PET/MRI compared to PET/CT in a lesion-based analysis was reported for all lesions together (77% versus 89%) in one study, osseous metastases (69–99% versus 92–98%) in two studies and hepatic metastases (70–75% versus 80–100%) in one study. Moreover, PET/MRI revealed a significantly higher amount of osseous metastases (90 versus 141) than PET/CT. PET/CT is associated with a statistically higher specificity than PET/MRI in the lesion detection of all lesions together (98% versus 96%) and of osseous metastases (100% versus 95%), both in one study. None of the reviewed studies reported significant differences between PET/CT and DWI for any of the evaluated sites. There is a trend toward higher specificity for PET/CT.
Conclusion
In general, there is a trend toward higher sensitivity and lower specificity of PET/MRI when compared to PET/CT. Results on the diagnostic performance of DWI are conflicting. Rather than evaluating it separate, it seems to have complementary value when combined with other MR sequences.

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https://journals.lww.com/nuclearmedicinecomm/Fulltext/2020/10000/Diagnostic_performance_of_PET_computed_tomography.1.aspx

Head-to-head comparison of the hybrid tracer indocyanine green-99mTc-nanocolloid with 99mTc-Senti-Scint using sentinel node lymphoscintigraphy and single-photon emission computed tomography combined with computer tomography in melanoma

imageObjective
The hybrid tracer indocyanine green (ICG)-99mTc-nanocolloid has been introduced for sentinel node imaging. However, until now, a comparison of this tracer with other radiocolloids with a larger particle size has not been effectuated. Based on a head-to-head evaluation in patients with melanoma, we have compared ICG-99mTc-nanocolloid (particle size 5–80 nm) with 99mTc-Senti-Scint (particle size 100–600 nm) to establish differences in drainage pattern and sentinel node localization using lymphoscintigraphy and single-photon emission computed tomography combined with computer tomography (SPECT-CT) in melanoma patients scheduled for sentinel node biopsy.
Methods
Twenty-five patients (mean age: 56.9 years, range: 25–79 years) with a melanoma scheduled for SLN biopsy prior to (re)excision of the primary lesion (scar) were prospectively included following a two-day procedure. The first day, after 99mTc-Senti-Scint injection in four intradermal depots around the primary lesion or scar, early/delayed lymphoscintigraphy and SPECT-CT images were acquired. The injection sites were marked. The second day, after assessing lymph node radioactivity using planar scintigraphy, ICG-99mTc-nanocolloid was injected at the previously marked skin points and imaging was performed. The paired planar and SPECT-CT images of both tracers were evaluated with respect to drainage patterns, SLN visualization and non-SLN appearing.
Results
Twenty-four out of 25 patients were evaluable. SLN visualization on a patient basis was 100% for ICG-99mTc-nanocolloid and 96% for 99mTc-Senti-Scint, whereas uptake in non-SLNs was found in, respectively, 71% (17/24) and 61% (14/23). Concordance in drainage to 45 lymph node basins was 91%. Discordant drainage was found for two melanomas in the head-and-neck and one in the clavicular area. Unique lymph node basins were seen in 44/45 (98%) for ICG-99mTc-nanocolloid and 42/45 (93%) for 99mTc-Senti-Scint. Concerning identified SLNs, the number was similar for both tracers (n = 58); however, more non-SLNs (65 vs 50) were visualized with ICG-99mTc-nanocolloid than with 99mTc-Senti-Scint.
Conclusion
A slightly higher SLN visualization accompanied by a tendency to depict more non-SLNs was found for ICG-99mTc-nanocolloid. Excepting the head and neck area, an overall high concordance in drainage was found for both radiotracers. With an additional value for the hybrid tracer due to the combination of preoperative imaging and the additional visual signal in the operation room, added by the fluorescent component of the hybrid tracer, there was a preference for ICG-99mTc-nanocolloid.

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https://journals.lww.com/nuclearmedicinecomm/Fulltext/2020/10000/Head_to_head_comparison_of_the_hybrid_tracer.3.aspx

Standardized uptake values and ratios on 68Ga-DOTATATE PET-computed tomography for normal organs and malignant lesions and their correlation with Krenning score in patients with metastatic neuroendocrine tumors

imageThe aim was to estimate the physiological standardized uptake values (SUVs) on 68Ga-DOTATATE PET-computed tomography (CT) in normal organs and metastatic tumor lesions (both standard and delayed), and correlating the uptake values and ratios with Krenning Scores (K-score) in patients with metastatic/advanced neuroendocrine tumors (NETs) undergoing PET-CT studies for their management work-up. A total of 32 patients of metastatic NET with 95 discrete tumor lesions were included in this analysis. These patients underwent standard whole-body PET-CT following injection of 2–3 mCi (74–111 MBq) of 68Ga-DOTATATE at 1–1.5 h. The normal physiological SUVmean of the liver and spleen and SUVmax and SUVmean of tumor lesions were estimated by an in-built automated procedure. These patients also underwent a delayed scan (2.5–3 h) and the same parameters were obtained for the delayed study. The tumorous lesions were further classified on the basis of K-score, and this was correlated with the mean SUVmax on both early and delayed scans. SUVmean ratios (tumor-to-liver and tumor-to-spleen) were also calculated for both time-points and correlated with individual K-scores. In lesions with K-score 4, the mean SUVmax was 32.5 in early and 30.5 in delayed scan, for lesions with K-score of 3 and 2, the mean SUVmax were 17.3, 20, and 9.3, 9.2, respectively, while in K-score 1 (n = 1), the delayed mean SUVmax was found to be more than early mean SUVmax (3.2 to 2.3). Statistical significance was evaluated by paired t test, and the changes in SUVmax was found to be statistically insignificant (P > 0.05) in all 3 K-scores. The paired t test was also performed between early and delayed tumor/liver and tumor/spleen mean SUVmean ratios, and no significant changes were observed across all K scores. The mean SUVmean values of the liver in the standard 1-h scan and delayed scans were 8.05 (range: 3–15) and 8.17 (range: 3.2–16), while for spleen, the values were 18 (range: 8.4–36.7) and 20 (range: 10–38.6), respectively. Statistically significant changes were observed in delayed spleen SUVmean values compared to the early scan (P < 0.05), while for liver SUVmean, the difference was not significant. Thus, in the present study, the SUVmax and SUVmean (range and mean values) for normal liver and spleen, and malignant NET lesions, and tumor-to-liver and tumor-to-spleen SUVmean ratios of different K-scores were generated. As could be theoretically expected in receptor-based PET-CT, there was no significant change in the delayed scan compared to the standard 1–1.5 h values

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https://journals.lww.com/nuclearmedicinecomm/Fulltext/2020/10000/Standardized_uptake_values_and_ratios_on.14.aspx

Inter- and intraobserver agreement in standard and ultra-fast single-photon emission computed tomography/computed tomography for the assessment of bone metastases

imageObjective
To investigate inter- and intraobserver agreement using standard (std)-single-photon emission computed tomography/computed tomography (SPECT/CT) or ultra-fast acquisition (UF)-SPECT/CT as an add-on to planar whole-body bone scintigraphy (WB-BS) for the detection of bone metastases in patients with known cancer.
Methods
Images from patients (n = 104) participating in a prospective trial comparing SPECT/CT as an add-on to WB-BS with two different acquisition methods (std-SPECT/CT; 20 s per view, 32 views and UF-SPECT/CT; 16 views of 10 s per view) were included. The combinations of WB-BS with the two different SPECT/CT acquisition methods were independently evaluated by two experienced observers using a three-point scale (M0: no metastases, Me: equivocal for bone metastases and M1: bone metastases). The observers re-evaluated the scans 6 months later. Inter- and intraobserver agreement was calculated using linear weighted kappa.
Results
The linear weighted kappa for the interobserver agreement was 0.78 [95% confidence interval (CI) 0.61–0.94] for WB-BS with std-SPECT/CT and 0.84 (95% CI 0.67–1.00) for WB-BS with UF-SPECT/CT. Similar values were observed for the intraobserver agreement, in which the linear weighted kappa was 0.76 (95% CI 0.60–0.92) and 0.73 (95% CI 0.57–0.90) for std-SPECT/CT and UF-SPECT/CT, respectively.
Conclusion
Satisfactory inter- and intraobserver agreement was seen for both acquisition methods, emphasizing that the use of SPECT/CT as an add-on to WB-BS is a robust method for the detection of bone metastases even when conducted with a very short acquisition time.

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https://journals.lww.com/nuclearmedicinecomm/Fulltext/2020/10000/Inter__and_intraobserver_agreement_in_standard_and.2.aspx