Clinical utility of F-18 FDG PET-CT in the initial evaluation of lung cancer.

PURPOSE: Positron emission tomography-computed tomography (PET-CT) is a resource-demanding imaging modality with increasing popularity in the workup of patients with suspected or proven lung cancer. METHODS: To review the clinical usefulness of this imaging modality in the diagnosis, staging, and pre-operative evaluation, we conducted a systematic literature search, review, and quality assessment using the rapid evidence assessment toolkit and the Oxford Centre for Evidence-Based Medicine methodology. The literature search resulted in 4,208 records including 918 reviews, of which 139 met the predefined criteria and were read in full to identify relevant original articles on F-18 FDG PET-CT (1) in the evaluation of solitary pulmonary nodules (n = 14), (2) in curative-intent treatment trials (n = 9), and (3) in planning of invasive procedures (n = 18). RESULTS: We found the following important results from the literature review: 1) PET-CT can rule out malignancy in most solitary pulmonary nodules due to high sensitivity (recommendation level A). 2) PET-CT reduces the number of futile treatment trials (recommendation level A). 3) The sensitivity of PET-CT in general is insufficient to rule out mediastinal lymph node metastasis (recommendation level A). CONCLUSIONS: ᅟ 1) With few exceptions, solitary pulmonary nodules can safely be considered benign if the PET-CT scan is negative. Exceptions consist of small (<1 cm) and non-solid, solitary pulmonary nodules. These abnormalities should be followed up by CT in a structured programme. 2) No curative-intent treatment should be commenced until a PET-CT scan has excluded occult distant metastases. 3) In general, lymph node metastasis in the mediastinum cannot be ruled out on the basis of a negative PET-CT, and confirmative invasive staging should be performed in most patients before mediastinal metastasis is confirmed or ruled out.

FDG PET/CT in cancer: comparison of actual use with literature-based recommendations.

PURPOSE: The Region of Southern Denmark (RSD), covering 1.2 of Denmark's 5.6 million inhabitants, established a task force to (1) retrieve literature evidence for the clinical use of positron emission tomography (PET)/CT and provide consequent recommendations and further to (2) compare the actual use of PET/CT in the RSD with these recommendations. This article summarizes the results. METHODS: A Work Group appointed a professional Subgroup which made Clinician Groups conduct literature reviews on six selected cancers responsible for 5,768 (62.6 %) of 9,213 PET/CT scans in the RSD in 2012. Rapid Evidence Assessment was applied, using the methodology of systematic reviews with predefined limitations to search PubMed, Embase and the Cochrane Library for articles published in English/Danish/Swedish/Norwegian since 2002. PICO questions were defined, data recorded and quality appraised and rated with regard to strength and evidence level. Consequent recommendations for applications of PET/CT were established. The actual use of PET/CT was compared with these, where grades A and B indicated "established" and "useful" and grades C and D "potentially useful" and "non-recommendable" indications, respectively. RESULTS: Of 11,729 citations, 1,729 were considered for review, and 204 were included. The evidence suggested usefulness of PET/CT in lung, lymphoma, melanoma, head and neck, and colorectal cancers, whereas evidence was sparse in gynaecological cancers. The agreement between actual use of PET/CT and literature-based recommendations was high in the first five mentioned cancers in that 96.2 % of scans were made for grade A or B indications versus only 22.2 % in gynaecological cancers. CONCLUSION: Evidence-based usefulness was reported in five of six selected cancers; evidence was sparse in the sixth, gynaecological cancers. Actual use of PET/CT agreed well with recommendations.

Ultra-low-dose CT for attenuation correction: dose savings and effect on PET quantification for protocols with and without tin filter.

BACKGROUND: Ultra-low-dose (ULD) computed tomography (CT) scans should be used when CT is performed only for attenuation correction (AC) of positron emission tomography (PET) data. A tin filter can be used in addition to the standard aluminium bowtie filter to reduce CT radiation dose to patients. The aim was to determine how low CT doses can be, when utilised for PET AC, with and without the tin filter, whilst providing adequate PET quantification. METHODS: A water-filled NEMA image quality phantom was imaged in three configurations with 18F-FDG: (1) water only (0HU); (2) with cylindrical insert containing homogenous mix of sand, flour and water (SFW, approximately 475HU); (3) with cylindrical insert containing sand (approximately 1100HU). Each underwent one-bed-position (26.3 cm) PET-CT comprising 1 PET and 13 CT acquisitions. CT acquisitions with tube current modulation were performed at 120 kV/50 mAs-ref (reference standard), 100 kV/7 mAs-ref (standard ULDCT for PET AC protocol), Sn140kV (mAs range 7-50-ref) and Sn100kV (mAs range 12-400-ref). PET data were reconstructed with µ-maps provided by each CT dataset, and PET activity concentration measured in each reconstruction. Differences in CT dose length product (DLP) and PET quantification were determined relative to the reference standard. RESULTS: At each tube voltage, changes in PET quantification were greater with increasing density and reducing mAs. Compared with the reference standard, differences in PET quantification for the standard ULDCT protocol for the three phantoms were ≤ 1.7%, with the water phantom providing a DLP of 7mGy.cm. With tin filter at Sn100kV, differences in PET quantification were negligible (≤ 1.2%) for all phantoms down to 50mAs-ref, proving a DLP of 2.8mGy.cm, at 60% dose reduction compared with standard ULDCT protocol. Below 50mAs-ref, differences in PET quantification were > 2% for at least one phantom (2.3% at 25mAs-ref in SFW; 6.4% at 12mAs-ref in sand). At Sn140kV/7mAs-ref, quantification differences were ≤ 0.6% in water, giving 3.8mGy.cm DLP, but increased to > 2% at bone-equivalent densities. CONCLUSIONS: CT protocols for PET AC can provide ultra-low doses with adequate PET quantification. The tin filter can allow 60-87% lower dose than the standard ULDCT protocol for PET AC, depending on tissue density and accepted change in PET quantification.

A randomised trial of [18F]PSMA-1007-PET/CT versus NaF-PET/CT for staging primary prostate cancer: A trial protocol.

Background: Prostate-specific membrane antigen (PSMA)-positron emission tomography/contrast-enhanced computed tomography (PET/CT) is a sensitive imaging modality for prostate cancer (PCa). Due to lack of knowledge of the patient benefit, PSMA-PET/CT is not yet recommended in the European guidelines for staging and treatment planning of patients with newly diagnosed PCa. We will investigate the potential difference in progression-free survival (PFS) and quality of life (QoL) of using PSMA-PET/CT versus sodium fluoride (NaF)-PET/CT for staging and treatment planning in patients with newly diagnosed PCa. Study Design: This is a prospective randomised controlled multicentre trial carried out at three centres in the Region of Southern Denmark. Endpoints: The primary endpoint is PFS. Secondary endpoints are residual disease, stage migration, impact on treatment strategies, stage distribution, QoL and diagnostic accuracy measures. Patients and Methods: Patients eligible for the study have newly diagnosed unfavourable intermediate- or high-risk PCa. A total of 448 patients will be randomised 1:1 into two groups: (A) a control group staged with Na[18F]F-PET/CT and (B) an intervention group staged with [18F]PSMA-1007-PET/CT. A subgroup in the intervention group will have a supplementary blinded Na[18F]F-PET/CT performed for the purpose of performing accuracy analyses. QoL will be assessed at baseline and with regular intervals (3-12 months) during the study period. Treatment decisions are achieved at multidisciplinary team conferences based on the results of the respective scans and according to current Danish guidelines. Trial Registration: The Regional Committees on Health Research Ethics for Southern Denmark (S-20190161) and the Danish Medicines Agency (EudraCT Number 2021-000123-12) approved the study, and it has been registered on clinicaltrials.gov (Record 2020110469).

Lesion detection in 18F-sodium fluoride bone imaging: a comparison of attenuation-corrected versus nonattenuation-corrected PET reconstructions from modern PET-CT systems.

OBJECTIVES: An earlier study demonstrated comparable lesion detection between attenuation-corrected (AC) and nonattenuation-corrected (NAC) 18F-sodium fluoride (NaF) PET images, which is relevant for computed tomography (CT) radiation dose-saving. However, this finding may not be applicable to newer systems. The aim was to compare lesion detection between AC and NAC NaF PET images on modern PET-CT systems. METHODS: One expert and one nonexpert observer retrospectively surveyed NaF PET data in 25 breast cancer patients. At both lesion and patient level, each observer classified bone abnormalities as malignant, equivocal or benign, from NAC and AC PET images in the absence of CT. Expert interpretation of NaF PET-CT with the review of all diagnostic imaging/pathology reports for at least the subsequent 12 months provided reference standard metastases status at the patient level. Two-tailed Wilcoxon signed-rank tests measured statistically significant differences in total lesion detection between AC and NAC PET. Quadratic-weighted kappa score measured agreement in patient metastases status between observers. RESULTS: On a lesion-basis, AC PET images showed significantly more lesions than NAC for both the expert (122 versus 96; P = 0.002) and nonexpert (146 versus 132; P = 0.036) observers, with a large number of patients demonstrating disparity between AC and NAC images. For metastases status at the patient level without CT, NAC PET showed slightly better diagnostic accuracy than AC due to fewer false-positive results, as fewer lesions were identified. CONCLUSION: AC PET data provided superior lesion detection to NAC in NaF bone examinations and are thus required for clinical interpretation.