Lymph Node Staging with a Combined Protocol of 18F-FDG PET/MRI and Sentinel Node SPECT/CT: A Prospective Study in Patients with FIGO I/II Cervical Carcinoma.

Lymph node metastasis (LNM) is present in a minority of patients with early stages of cervical carcinomas. As conventional imaging including PET/CT has shown limited sensitivity, systematic lymphadenectomies are often conducted for staging purposes. Therefore, the aim of this prospective study was to analyze the impact of 18F-FDG PET/MRI in addition to sentinel lymph node (SLN) biopsy on lymph node (LN) status. Methods: Forty-two women with an initial diagnosis of Fédération Internationale de Gynécologie et d'Obstétrique (FIGO) IA-IIB cervical carcinoma were included between March 2016 and April 2019. Each patient underwent preoperative whole-body 18F-FDG PET/MRI and SLN imaging with SPECT/CT after intracervical injection of 99mTc-labeled nanocolloid. Systematic lymphadenectomy and SLN biopsy served as the reference standard. Staging using PET/MRI was performed by nuclear medicine and radiology experts working in consensus. Results: One patient was excluded from surgical staging because of liver metastases newly diagnosed on PET/MRI. The overall prevalence of LNM in the remaining 41 patients was 29.3% (12/41). Five of 12 patients with LNM had solely small metastases with a maximum diameter of 5 mm. The consensus interpretation showed PET/MRI to have a specificity of 100% (29/29; 95% CI, 88.3%-100%) for LNM staging but a low sensitivity, 33.3% (4/12; 95% CI, 12.8%-60.9%). LN size was the most important factor for the detectability of metastases, since only LNMs larger than 5 mm could be identified by PET/MRI (sensitivity, 57.1% for >5 mm and 0% for ≤5 mm). Paraaortic LNM was evaluated accurately in 3 of the 4 patients with paraaortic LN metastasis. SLNs were detectable by SPECT/CT in 82.9% of the patients or 69.0% of the hemipelves. In cases with an undetectable SLN on SPECT/CT, the malignancy rate was considerably higher (31.2% vs. 19.3%). The combination of PET/MRI and SLN SPECT/CT improved the detection of pelvic LNM from 33.3% to 75%. Conclusion:18F-FDG PET/MRI is a highly specific N-staging method and improves LNM detection. Because of the limited sensitivity in frequently occurring small LNMs, PET/MRI should be combined with SLN mapping. The proposed combined protocol helps to decide whether extensive surgical staging is necessary in patients with FIGO I/II cervical cancer.

Influence of 99m-Tc-Nanocolloid Activity Concentration on Sentinel Lymph Node Detection in Endometrial Cancer: A Quantitative SPECT/CT Study.

This study evaluates quantitative combined single photon emission tomography/computed x-ray tomography (SPECT/CT) to assess the influence of radiotracer concentration on detection of sentinel lymph nodes (SLN) in endometrial cancer (EC). Eighty EC patients underwent pericervical 99m-Tc-nanocolloid injection followed by SPECT/CT. The subgroup of patients with failed SLN detection in SPECT/CT (n = 20) was compared to match-paired patients showing at least two SLNs. Results of intraoperative gamma probe measurements and quantitative SPECT/CT were used for comparison. In patients with detection failure, the percentage of injected dose, absolute activity, and volume of the injection site were significantly lower (30 ± 24% vs. 55 ± 19%; p = 0.01, 43 ± 36 MBq vs. 73 ± 33 MBq; p = 0.04, and 183 ± 164 mL vs. 266 ± 164 mL; p = 0.03) while mean activity concentration in liver, spleen, and bone marrow was significantly higher (p = 0.02). Activity concentration (>33 KBq/mL) and absolute activity (>73 MBq) of injection areas correlated with successful intraoperative SLN detection. In a subgroup of 19 SLNs, a correlation between SPECT/CT-derived uptake and intraoperative count rate was found (R2 = 0.8; p < 0.001). SLN detection in EC patients depended on high radiotracer activity at the cervical injection site. Quantitative SPECT/CT could predict successful intraoperative SLN detection and may help to optimize injection technique.

Automated Definition of Skeletal Disease Burden in Metastatic Prostate Carcinoma: A 3D Analysis of SPECT/CT Images.

To meet the current need for skeletal tumor-load estimation in castration-resistant prostate cancer (CRPC), we developed a novel approach based on adaptive bone segmentation. In this study, we compared the program output with existing estimates and with the radiological outcome. Seventy-six whole-body single-photon emission computed tomographies/x-ray computed tomography with 3,3-diphosphono-1,2-propanedicarboxylic acid from mCRPC patients were analyzed. The software identified the whole skeletal volume (SVol) and classified the voxels metastases (MVol) or normal bone (BVol). SVol was compared with the estimation of a commercial software. MVol was compared with manual assessment and with prostate specific antigen (PSA) levels. Counts/voxel were extracted from MVol and BVol. After six cycles of 223RaCl2-therapy every patient was re-evaluated as having progressive disease (PD), stable disease (SD), or a partial response (PR). SVol correlated with that of the commercial software (R = 0.99, p < 0.001). MVol correlated with the manually-counted lesions (R = 0.61, p < 0.001) and PSA (R = 0.46, p < 0.01). PD had a lower counts/voxel in MVol than PR/SD (715 ± 190 vs. 975 ± 215 and 1058 ± 255, p < 0.05 and p < 0.01) and BVol (PD 275 ± 60, PR 515 ± 188 and SD 528 ± 162 counts/voxel, p < 0.001). Segmentation-based tumor load correlated with radiological/laboratory indices. Uptake was linked with the clinical outcome, suggesting that metastases in PD patients have a lower affinity for bone-seeking radionuclides and might benefit less from bone-targeted radioisotope therapies.

Pancreatic Ductal Adenocarcinoma With High Radiotracer Uptake in 68Ga-Prostate-Specific Membrane Antigen PET/CT.

Prostate-specific membrane antigen imaging with PET/CT is increasingly used in prostate cancer and was shown to have a high diagnostic performance. We report a clinical case of a 67-year-old man with previous history of operated prostate cancer and increasing prostate-specific antigen blood level. Ga-HBED-CC prostate-specific membrane antigen PET/CT imaging was indicated for the assessment of local recurrence and lymph node metastases of prostate cancer. In addition, a soft tissue mass in the body of the pancreas with high radiotracer uptake was detected. Histopathology confirmed a pancreatic ductal adenocarcinoma.

Sentinel lymph node mapping using SPECT/CT and gamma probe in endometrial cancer: an analysis of parameters affecting detection rate.

PURPOSE: SPECT/CT after pericervical injection of technetium-99 m-nanocolloid was shown to be suitable for sentinel lymph node (SLN) mapping in endometrial cancer (EC). The aim of this study was to analyze factors affecting successful SLN detection by means of SPECT/CT such as imaging findings, patient characteristics and tumor biology in a large cohort of patients. METHODS: One hundred and forty-five consecutive patients suffering from EC who received pre-surgical SLN mapping at our institution between 2011 and 2016 were included in this analysis. SPECT/CT data of abdomen and pelvis (mean 4:20 ± 1:20 h p.i.) were acquired after pericervical injection of technetium-99 m-nanocolloid (mean 230 ± 45 MBq) in all patients. Surgical staging was performed on the day after. Acquisition parameters, patient characteristics, SPECT/CT findings as well as histopathological results were collected. RESULTS: A total of 282 SLNs were identified by means of SPECT/CT. Overall, preoperative and intraoperative SLN detection rates were 86%, 76% and 74% respectively. The most important factor associated with failure to detect SLNs was the presence of high bone marrow on SPECT/CT (p = 0.005). Peritoneal/abdominal radioactivity was also associated with missed SLN detection in SPECT/CT (p = 0.02). However, the presence of liver/spleen uptake on its own was not predictive for detection failure. Low numbers of detected SLNs in SPECT/CT were slightly related with older age and lower injected activity. No significant influence was found for the parameters of tumor histology and stage, lymph node involvement and the time gap between injection and imaging. CONCLUSIONS: Venous drainage as indicated by bone marrow uptake is the most important factor associated with scintigraphic SLN detection failure. Moreover, high peritoneal and abdominal activity was also associated with detection failure. Thus, meticulous application of the radiotracer is crucial in EC.

Tumor Burden and Intraosseous Metabolic Activity as Predictors of Bone Marrow Failure during Radioisotope Therapy in Metastasized Prostate Cancer Patients.

RATIONALE: Radium-223-Dichloride (Ra-223) is an alpha-emitter, used to treat bone metastases. Patients with high metastatic burden and/or with increased trabecular bone uptake could present a higher incidence of hematologic toxicity. We hypothesized that these two factors are predictors of bone marrow failure. MATERIAL AND METHODS: A computer algorithm discriminated between trabecular bone (BVol) and tumor metastases (MVol) within pretherapeutic whole-body skeletal SPECT/CT (N = 47). The program calculated the metastatic invasion percent (INV%) as the MVol/(MVol + BVol) ratio and extracted the BVol mean counts. BVol counts were correlated to % drop of hemoglobin (Hb), leukocytes (WBC), and platelets (PLT) after 3/6 Ra-223 cycles. Patient-specific and computational-derived parameters were tested as predictors of hematologic toxicity with MANOVA. RESULTS: BVol counts correlated with drop of Hb (R = 0,65, p < 0.01) and PLT (R = 0,45, p < 0.01). Appendicular BVol counts showed a better correlation (p < 0.05, p < 0.01, and p < 0.001 for Hb, WBC, and PLT, resp.). INV% directly correlated with BVol counts (R = 0.68, p < 0.001). At MANOVA, grade III/IV toxicity was predicted by INV% (p < 0.01), by long-bone invasion (p < 0.005), and by BVol counts (p < 0.05). CONCLUSIONS: In patients with significant bone tumor burden, degree of bone invasion and trabecular bone uptake are predictors of subsequent bone marrow failure.

Pericervical Injection of 99mTc-Nanocolloid Is Superior to Peritumoral Injection for Sentinel Lymph Node Detection of Endometrial Cancer in SPECT/CT.

PURPOSE: Scintigraphic mapping of sentinel lymph node (SLN) is increasingly performed in patients with endometrial carcinoma although its routine clinical use is still under investigation. The purpose of this study was to compare preoperative SLN detection by means of SPECT/CT using pericervical (PC) versus hysteroscopic peritumoral (PT) injection. PATIENTS AND METHODS: One hundred forty consecutive patients with endometrial carcinoma who underwent surgery and preoperative SLN SPECT/CT with Tc-nanocolloid were included. Seventy women received hysteroscopic injection at 3 PT sites, and 70 women received PC injection at 3-, 6-, 9-, and 12-o'clock positions. Each patient underwent SPECT/CT followed by modified radical hysterectomy with lymphadenectomy on the day after. Histopathological results were collected for validation. RESULTS: Three hundred thirty-four SLNs were detected by SPECT/CT in 106 patients (mean, 3.15; range, 1-9). The detection rate after PC nanocolloid injection was 83% versus 69% after PT injection (Pearson χ test, P = 0.049). However, PT application resulted in a higher rate of para-aortic SLNs (PC: 60% vs PT: 38% of positive scans, P = 0.02). SPECT/CT yielded an overall sensitivity of 70% for the SLN detection in women with lymph node metastases with 3 false-negative cases. Failure to detect SLN was mostly associated with uptake in the reticuloendothelial system (liver, spleen, and bone marrow) or peritoneal diffusion in both cohorts. Negative scans after PT application often showed a minor to even failing injection depot. CONCLUSIONS: Pericervical injection leads to a significantly better detection rate of SLN on SPECT/CT while reducing invasiveness of the injection procedure. Failure to detect SLN seems to be associated with major venous drainage.