Christina Bluemel

68Ga-PSMA-PET/CT in Patients With Biochemical Prostate Cancer Recurrence and Negative 18F-Choline-PET/CT.

Purpose Investigating the value of 68Ga-PSMA-PET/CT in biochemically recurring prostate cancer patients with negative 18F-choline-PET/CT. Patients and Methods One hundred thirty-nine consecutive patients with biochemical recurrence after curative (surgery and/or radiotherapy) therapy were offered participation in this sequential clinical imaging approach. Patients first underwent an 18F-choline-PET/CT. If negative, an additional 68Ga-PSMA-PET/CT was offered. One hundred twenty-five of 139 eligible patients were included in the study; 32 patients underwent additional 68Ga-PSMA-PET/CT. Patients with equivocal findings (n = 5) on 18F-choline-PET/CT and those who declined the additional 68Ga-PSMA-PET/CT (n = 9) were excluded. Images were analyzed visually for the presence of suspicious lesions. Findings on PET/CT were correlated with PSA level, PSA doubling time (dt), and PSA velocity (vel). Results The overall detection rates were 85.6% (107/125) for the sequential imaging approach and 74.4% (93/125) for 18F-choline-PET/CT alone. 68Ga-PSMA-PET/CT detected sites of recurrence in 43.8% (14/32) of the choline-negative patients. Detection rates of the sequential imaging approach and 18F-choline-PET/CT alone increased with higher serum PSA levels and PSA vel. Subgroup analysis of 68Ga-PSMA-PET/CT in 18F-choline negative patients revealed detection rates of 28.6%, 45.5%, and 71.4% for PSA levels of 0.2 or greater to less than 1 ng/mL, 1 to 2 ng/mL, and greater than 2 ng/mL, respectively. Conclusions The sequential imaging approach designed to limit 68Ga-PSMA imaging to patients with negative choline scans resulted in high detection rates. 68Ga-PSMA-PET/CT identified sites of recurrent disease in 43.8% of the patients with negative 18F-choline PET/CT scans.

Biodistribution and Radiation Dosimetry for a Probe Targeting Prostate-Specific Membrane Antigen for Imaging and Therapy

Prostate-specific membrane antigen (PSMA) is a promising target for diagnosis and treatment of prostate cancer. EuK-Subkff-68Ga-DOTAGA (68Ga-PSMA Imaging & Therapy [PSMA I&T]) is a recently introduced PET tracer for imaging PSMA expression in vivo. Whole-body distribution and radiation dosimetry of this new probe were evaluated. Methods: Five patients with a history of prostate cancer were injected intravenously with 91–148 MBq of 68Ga-PSMA I&T (mean ± SD, 128 ± 23 MBq). After an initial series of rapid whole-body scans, 3 static whole-body scans were acquired at 1, 2, and 4 h after tracer injection. Time-dependent changes of the injected activity per organ were determined. Mean organ-absorbed doses and effective doses were calculated using OLINDA/EXM. Results: Injection of 150 MBq of 68Ga-PSMA I&T resulted in an effective dose of 3.0 mSv. The kidneys were the critical organ (33 mGy), followed by the urinary bladder wall and spleen (10 mGy each), salivary glands (9 mGy each), and liver (7 mGy). Conclusion: 68Ga-PSMA I&T exhibits a favorable dosimetry, delivering organ doses that are comparable to (kidneys) or lower than those delivered by 18F-FDG.

Biodistribution and Radiation Dosimetry for the Chemokine Receptor CXCR4-Targeting Probe 68Ga-Pentixafor

68Ga-pentixafor is a promising PET tracer for imaging the expression of the human chemokine receptor 4 (CXCR4) in vivo. The whole-body distribution and radiation dosimetry of 68Ga-pentixafor were evaluated. Methods: Five multiple-myeloma patients were injected intravenously with 90–158 MBq of 68Ga-pentixafor (mean ± SD, 134 ± 25 MBq), and a series of 3 rapid multiple-bed-position whole-body scans were acquired immediately afterward. Subsequently, 4 static whole-body scans followed at 30 min, 1 h, 2 h, and 4 h after administration of the radiopharmaceutical. Venous blood samples were obtained. Time-integrated activity coefficients were determined from multiexponential regression of organ region-of-interest data normalized to the administered activity, for example, the time-dependent percentages of the injected activity per organ. Mean organ-absorbed doses and effective doses were calculated using OLINDA/EXM. Results: The effective dose based on 150 MBq of 68Ga-pentixafor was 2.3 mSv. The highest organ-absorbed doses (for 150 MBq injected) were found in the urinary bladder wall (12.2 mGy), spleen (8.1 mGy), kidneys (5.3 mGy), and heart wall (4.0 mGy). Other organ mean absorbed doses were as follows: 2.7 mGy, liver; 2.1 mGy, red marrow; 1.7 mGy, testes; and 1.9 mGy, ovaries. Conclusion: 68Ga-pentixafor exhibits a favorable dosimetry, delivering absorbed doses to organs that are lower than those delivered by 18F-FDG– or 68Ga-labeled somatostatin receptor ligands.

Cost-Effectiveness of Hybrid PET/CT for Staging of Non–Small Cell Lung Cancer

Although the diagnostic effectiveness of integrated PET/CT for staging of non–small cell lung cancer (NSCLC) has already been proven, it remains to be determined if tumor staging with combined metabolic and anatomic imaging is also cost-effective. The objective of this study was to evaluate from a payers’ perspective the cost-effectiveness of staging NSCLC with CT alone (representing the mainstay diagnostic test) and with integrated PET/CT. Methods: The study is based on 172 NSCLC patients from a prospective clinical study who underwent diagnostic, contrast-enhanced helical CT and integrated PET/CT. Imaging was performed at the University Hospital Ulm between May 2002 and December 2004. To calculate treatment costs, we differentiated among cost for diagnosis, cost for nonsurgical treatment according to the clinical diagnosis, and cost for surgical procedures according to the clinical tumor stage. Results: The diagnostic effectiveness in terms of correct TNM staging was 40% (31/77) for CT alone and 60% (46/77) for PET/CT. For the assessment of resectability (tumor stages Ia–IIIa vs. IIIb–IV), 65 of 77 patients (84%) were staged correctly by PET/CT (CT alone, 70% [54/77]). The incremental cost-effectiveness ratios per correctly staged patient were

Comparison of the Amino Acid Tracers 18F-FET and 18F-DOPA in High-Grade Glioma Patients

3,508 for PET/CT versus CT alone. The incremental cost-effectiveness ratios per quality-adjusted life year gained were

First-in-Human Experience of CXCR4-Directed Endoradiotherapy with 177Lu- and 90Y-Labeled Pentixather in Advanced-Stage Multiple Myeloma with Extensive Intra- and Extramedullary Disease

79,878 for PET/CT vs. CT alone, decreasing to

Freehand SPECT-guided sentinel lymph node biopsy in early oral squamous cell carcinoma.

69,563 assuming a reduced loss of utility (0.10 quality-adjusted life years) due to surgical morbidity. Conclusion: Cost-effectiveness analyses showed that costs for PET/CT are within the commonly accepted range for diagnostic tests or therapies. Therefore, reimbursement of PET/CT for NSCLC staging can be also recommended from an economic point of view.

EANM practice guidelines for lymphoscintigraphy and sentinel lymph node biopsy in melanoma

High-grade gliomas (HGGs) are the most common malignant primary tumors of the central nervous system. PET probes of amino acid transport such as O-(2-18F-fluoroethyl)-l-tyrosine (18F-FET), 3,4-dihydroxy-6-18F-fluoro-l-phenylalanine (18F-DOPA), and 11C-methionine (11C-MET) detect primary and recurrent tumors with a high accuracy. 18F-FET is predominantly used in Europe, whereas amino acid transport imaging is infrequently done in the United States. The aim of this study was to determine whether 18F-FET and 18F-DOPA PET/CT provide comparable information in HGG. Methods: Thirty 18F-FET and 18F-DOPA PET/CT scans were obtained before surgery or biopsy in 27 patients with high clinical suspicion for primary or recurrent HGG (5 primary, 22 recurrent tumors). 18F-FET and 18F-DOPA PET/CT images were compared visually and semiquantitatively (maximum standardized uptake value [SUVmax], mean SUV [SUVmean]). Background (SUVmax and SUVmean) and tumor-to-background ratios (TBRs) were calculated for both PET probes. The degree of 18F-DOPA uptake in the basal ganglia (SUVmean) was also assessed. Results: Visual analysis revealed no difference in tumor uptake pattern between the 2 PET probes. The SUVmean and SUVmax for 18F-FET were higher than those of 18F-DOPA (4.0 ± 2.0 and 4.9 ± 2.3 vs. 3.5 ± 1.6 and 4.3 ± 2.0, respectively; all P < 0.001). TBRs for SUVmean but not for SUVmax were significantly higher for 18F-FET than 18F-DOPA (TBR SUVmean: 3.8 ± 1.7 vs. 3.4 ± 1.2, P = 0.004; TBR SUVmax: 3.3 ± 1.6 and 3.0 ± 1.1, respectively; P = 0.086). 18F-DOPA uptake by the basal ganglia was present (SUVmean, 2.6 ± 0.7) but did not affect tumor visualization. Conclusion: Whereas visual analysis revealed no significant differences in uptake pattern for 18F-FET and 18F-DOPA in patients with primary or recurrent HGG, both SUVs and TBRs for SUVmean were significantly higher for 18F-FET. However, regarding tumor delineation, both tracers performed equally well and seem equally feasible for imaging of primary and recurrent HGG. These findings suggest that both PET probes can be used based on availability in multicenter trials.

68Gallium- and 90Yttrium-/177Lutetium: “theranostic twins” for diagnosis and treatment of NETs

Chemokine receptor 4 (CXCR4) is a key factor for tumor growth and metastasis in several types of human cancer. Based on promising experiences with a radiolabeled CXCR4 ligand (68Ga-pentixafor) for diagnostic receptor targeting, 177Lu- and 90Y-pentixather were recently developed as endoradiotherapeutic vectors. Here, we summarize the first-in-human experience in 3 heavily pretreated patients with intramedullary and extensive extramedullary manifestations of multiple myeloma undergoing CXCR4-directed endoradiotherapy. Methods: CXCR4 target expression was demonstrated by baseline 68Ga-pentixafor PET. Each treatment was approved by the clinical ethics committee. Pretherapeutic 177Lu-pentixather dosimetry was performed before 177Lu-pentixather or 90Y-pentixather treatment. Subsequently, patients underwent additional chemotherapy and autologous stem cell transplantation for bone marrow rescue. Results: A remarkable therapeutic effect was visualized in 2 patients, who showed a significant reduction in 18F-FDG uptake. Conclusion: CXCR4-targeted radiotherapy with pentixather appears to be a promising novel treatment option in combination with cytotoxic chemotherapy and autologous stem cell transplantation, especially for patients with advanced multiple myeloma.

Intensified Neoadjuvant Chemotherapy with Nab-Paclitaxel plus Gemcitabine Followed by FOLFIRINOX in a Patient with Locally Advanced Unresectable Pancreatic Cancer

In oral squamous cell carcinoma (OSCC), cervical lymph node status is the most important prognostic factor. Compared to elective neck dissection, reduced morbidity and better quality of life was demonstrated for sentinel lymph node biopsy, which is controversial because of the reduced detection rate of sentinel lymph nodes in close proximity to the injection site (also known as the shine‐through phenomenon).