PET-MR imaging using a tri-modality PET/CT-MR system with a dedicated shuttle in clinical routine

Tri-modality PET/CT-MRI includes the transfer of the patient on a dedicated shuttle from one system into the other. Advantages of this system include a true CT-based attenuation correction, reliable PET-quantification and higher flexibility in patient throughput on both systems. Comparative studies of PET/MRI versus PET/CT are readily accomplished without repeated PET with a different PET scanner at a different time point. Additionally, there is a higher imaging flexibility based on the availability of three imaging modalities, which can be combined for the characterization of the disease. The downside is a somewhat higher radiation dose of up to 3mSv with a low dose CT based on the CT-component, longer acquisition times and potential misalignment between the imaging components. Overall, the tri-modality PET/CT-MR system offers comparative studies using the three different imaging modalities in the same patient virtually at the same time, and may help to develop reliable attenuation algorithms at the same tim

Standardized classification schemes in reporting oncologic PET/CT

The imaging report is essential for the communication between physicians in patient care. The information it contains must be clear, concise with evidence-based conclusions and sufficient to support clinical decision-making. In recent years, several classification schemes and/or reporting guidelines for PET have been introduced. In this manuscript, we will review the classifications most frequently used in oncology for interpreting and reporting 18F-FDG PET imaging in lymphoma, multiple myeloma, melanoma and head and neck cancers, PSMA-ligand PET imaging for prostate cancer, and 68Ga-DOTA-peptide PET in neuroendocrine tumors (NET)

EANM/EARL harmonization strategies in PET quantification: from daily practice to multicentre oncological studies

Quantitative positron emission tomography/computed tomography (PET/CT) can be used as diagnostic or prognostic tools (i.e. single measurement) or for therapy monitoring (i.e. longitudinal studies) in multicentre studies. Use of quantitative parameters, such as standardized uptake values (SUVs), metabolic active tumor volumes (MATVs) or total lesion glycolysis (TLG), in a multicenter setting requires that these parameters be comparable among patients and sites, regardless of the PET/CT system used. This review describes the motivations and the methodologies for quantitative PET/ CT performance harmonization with emphasis on the EANM Research Ltd. (EARL) Fluorodeoxyglucose (FDG) PET/CT accreditation program, one of the international harmonization programs aiming at using FDG PET as a quantitative imaging biomarker. In addition, future accreditation initiatives will be discussed. The validation of the EARL accreditation program to harmonize SUVs and MATVs is described in a wide range of tumor types, with focus on therapy assessment using either the European Organization for Research and Treatment of Cancer (EORTC) criteria or PET Evaluation Response Criteria in Solid Tumors (PERCIST), as well as liver-based scales such as the Deauville score. Finally, also presented in this paper are the results from a survey across 51 EARL-accredited centers reporting how the program was implemented and its impact on daily routine and in clinical trials, harmonization of new metrics such as MATV and heterogeneity features

Head and neck squamous cell carcinoma (HNSCC) - detection of synchronous primaries with 18F-FDG-PET/CT

Purpose: The aim of the study was to evaluate 18F-FDG-PET/CT for the detection of synchronous primaries at initial staging of patients with head and neck squamous cell carcinoma (HNSCC). Methods: FDG-PET/CT images acquired between March 2001 and October 2007 in 589 consecutive patients (147 women, 442 men; mean age 61.5years, age range 32-97years) with proven HNSCC were reviewed for the presence of synchronous primaries. Cytology, histology and/or clinical and imaging follow-up served as reference standard. Results: FDG-PET/CT showed 69 suspected synchronous primaries in 62 patients of which 56 were finally confirmed in 44 patients. Of the 56 second cancers, 46 (82%) were found in the aerodigestive tract in the following locations: lung (26, 46%), head and neck (15, 17%), oesophagus (5, 9%). Ten second cancers (18%) were located outside the aerodigestive tract (colon, five; stomach, lymphoma, breast, thymus and kidney, one each). Six patients had three synchronous primaries and three patients had four synchronous cancers. Nine synchronous cancers were not detected by PET/CT (four head and neck, two lung, two oesophageal, one gastric). False-positive PET/CT findings were mainly related to benign FDG uptake in the intestine due to benign or precancerous polyps or physiological FDG uptake in other head and neck regions. Overall the prevalence of synchronous second primaries according to the reference standard was 9.5%, of which 84% were detected with FDG-PET/CT. In 80% of the patients, therapy was changed because of the detection of a synchronous primary. Conclusion: FDG-PET/CT detects a considerable number of synchronous primaries (8.0% prevalence) at initial staging of patients with HNSCC. Synchronous cancers were predominantly located in the aerodigestive tract, primarily in the lung, head and neck and oesophagus. Detection of second primaries has an important impact on therapy. PET/CT should be performed before panendoscop

Feasibility of integrated CT-liver perfusion in routine FDG-PET/CT

Objective: To integrate CT-perfusion into a routine, clinical contrast-enhanced (ce) PET/CT protocol for the evaluation of liver metastases and to compare functional CT and PET parameters. Materials and methods: Forty-six consecutive patients (mean age: 60 (34-82) years; 20 f, 26m) with known liver lesions (colorectal metastases (n=34), primary liver cancer (n=4), breast cancer (n=3), anal cancer, gastric cancer, esophageal cancer, GIST, duodenal cancer (all: n=1) who were referred for staging or therapy follow-up by [18F]-Fluoro-2-deoxy-D-glucose-positron-emission-tomography/computed-tomography imaging (FDG-PET/CT) were included. After acquisition of a low-dose PET/CT, a split-injection (70-90mL) ce-CT-protocol, including a 35-s CT-perfusion scan of the liver and a diagnostic ce-CT of the thorax and/or abdomen (70s delay, iv-contrast volume: 90mL, 4mL/s) was performed. CT-perfusion parameters (BF, BV, MTT,) and semi-quantitative PET-parameters (SUVmax, SUVmean, TLG, PETvol) were analyzed and compared. Results: CT-perfusion data could be obtained in all but one patient with shallow breathing. In all patients, diagnostic ce-PET/CT quality was adequate without the use of additional contrast media. Significant correlations (P<0.05) were found for each of BF, BV, MTT, and SUVmax, further, BF and MTT correlated with TLG. Several other correlations were seen for other perfusion and PET-parameters. Conclusion: Combined CT-perfusion/PET/CT-protocol without the use of additional contrast media is feasible and can be easily integrated in clinical routine. Perfusion parameters and PET-parameters are only partly correlating and therefore have to be investigated further at fixed time points during the course of disease and therap

Clinical value of a combined multi-phase contrast enhanced DOPA-PET/CT in neuroendocrine tumours with emphasis on the diagnostic CT component

Objective: To assess the clinical value of multi-phase, contrast-enhanced DOPA-PET/CT with emphasis on the diagnostic CT component in patients with neuroendocrine tumours (NET). Methods: Sixty-five patients with NET underwent DOPA-cePET/CT. The DOPA-PET, multi-phase CT and combined DOPA cePET/CT data were evaluated and diagnostic accuracies compared. The value of ceCT in DOPA cePET/CT concerning lesion detection and therapeutic impact was evaluated. Sensitivities, specificities and accuracies were calculated. Histopathology and clinical follow-up served as the standard of reference. Differences were tested for statistical significance by McNemar's test. Results: In 40 patients metastatic and/or primary tumour lesions were detected. Lesion-based analysis for the DOPA-PET showed sensitivity, specificity and accuracy of 66%, 100% and 67%, for the ceCT data 85%, 71% and 85%, and for the combined DOPA cePET/CT data 97%, 71% and 96%. DOPA cePET/CT was significantly more accurate compared with dual-phase CT (p < 0.05) and PET alone (p < 0.05). Additional lesion detection was based on ceCT in 12 patients; three patients underwent significant therapeutic changes based on the ceCT findings. Conclusion: DOPA cePET/CT was significantly more accurate than DOPA-PET alone and ceCT alone. The CT component itself had a diagnostic impact in a small percentage but contributed to the therapeutic strategies in selected patient

Diagnostic accuracy of contrast-enhanced FDG-PET/CT in primary staging of cutaneous malignant melanoma

Purpose: To evaluate the diagnostic accuracy of contrast-enhanced FDG-PET/CT (ce-PET/CT), PET-only, and CT-only in patients with newly diagnosed and resected cutaneous malignant melanoma. Methods: A final group of 56 patients (mean age 62years, range 23-86years; 29 women, 27 men) were staged with ce-PET/CT after resection of the primary tumour. Histopathology as well as clinical follow-up (mean 780days, range 102-1,390 days) served as the standards of reference. Differences between the staging modalities were tested for statistical significance with McNemar's test. Results: All imaging procedures provided low sensitivities in the detection of lymph nodes (sensitivity N-stage: PET/CT and PET-only 38.5%; CT-only 23.1%) and distant metastases (sensitivity M-stage: PET/CT 41.7%, PET-only 33.3%, CT-only 25.0%) in initial staging after resection of the primary tumour. No statistically significant differences were detected between the imaging procedures (p > 0.05). PET/CT resulted in an alteration in further treatment in two patients compared to PET-only and in four patients compared to CT-only. Conclusion: All imaging modalities had a low sensitivity on initial staging of patients with malignant melanoma. Thus, close patient follow-up must be considered mandator

Characterization of the impact to PET quantification and image quality of an anterior array surface coil for PET/MR imaging

Object: The aim of this study was to determine the impact to PET quantification, image quality and possible diagnostic impact of an anterior surface array used in a combined PET/MR imaging system. Materials and methods: An extended oval phantom and 15 whole-body FDG PET/CT subjects were re-imaged for one bed position following placement of an anterior array coil at a clinically realistic position. The CT scan, used for PET attenuation correction, did not include the coil. Comparison, including liver SUVmean, was performed between the coil present and absent images using two methods of PET reconstruction. Due to the time delay between PET scans, a model was used to account for average physiologic time change of SUV. Results: On phantom data, neglecting the coil caused a mean bias of −8.2% for non-TOF/PSF reconstruction, and −7.3% with TOF/PSF. On clinical data, the liver SUV neglecting the coil presence fell by −6.1% (±6.5%) for non-TOF/PSF reconstruction; respectively −5.2% (±5.3%) with TOF/PSF. All FDG-avid features seen with TOF/PSF were also seen with non-TOF/PSF reconstruction. Conclusion: Neglecting coil attenuation for this anterior array coil results in a small but significant reduction in liver SUVmean but was not found to change the clinical interpretation of the PET images