Somatostatin receptor imaging with 68Ga DOTATATE PET/CT: clinical utility, normal patterns, pearls, and pitfalls in interpretation.

Gallium 68 ((68)Ga) 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-octreotate (DOTATATE, GaTate) positron emission tomography (PET)/computed tomography (CT) is an imaging technique for detecting and characterizing neuroendocrine tumors (NETs). GaTate, a somatostatin analog, has recently been accorded orphan drug status by the U.S. Food and Drug Administration, thereby increasing interest in and availability of this radiotracer. GaTate PET/CT allows whole-body imaging of cell surface expression of somatostatin receptors (SSTRs) and is rapidly evolving as the new imaging standard of reference for the detection and characterization of NETs. The authors discuss the normal appearance at GaTate PET/CT and the utility of this modality in a variety of these tumors, including gastrointestinal, pancreatic, and bronchial NETs as well as pheochromocytoma, paraganglioma, meningioma, and oncogenic osteomalacia. In addition, they discuss potential causes of false-positive findings, including pancreatic uncinate process activity, inflammation, osteoblastic activity, and splenosis. They also highlight the complementary role of 2-[fluorine-18]fluoro-2-deoxy-d-glucose (FDG) PET/CT, including the advantages of using both GaTate PET/CT and FDG PET/CT to evaluate sites of well- and poorly differentiated disease. The use of GaTate PET/CT together with FDG PET/CT allows identification of tumor heterogeneity, which provides prognostic information and can be pivotal in guiding biopsy. It also allows optimal patient management, including theranostic application of peptide receptor radionuclide therapy, and the restaging of patients following therapy.

Diagnostic evaluation for interventional bronchoscopists and radiologists in lung cancer practice.

The global epidemic of lung cancer shows no signs of abating. It is generally accepted that accurate and cost-efficient diagnostic evaluation is the first important step to achieve the best outcomes of treatment. This is true in the context of disease confirmation, treatment planning, treatment monitoring, detection of and management of treatment failure or prognostication. Fortunately, major advances in the diagnostic evaluation of lung cancer have been made in the past three decades allowing more patients to get the appropriate treatment at the right time. This paper outlines how computed tomography, positron emission tomography/computed tomography and endobronchial ultrasound contribute to lung cancer management and discuss their strengths and weaknesses and their complimentary roles at different stages of lung cancer management. Due to financial constraint and reimbursement restrictions, not all clinically important advances in the diagnostic evaluation of lung cancer have been readily accepted into routine clinical care. This enforces the need to maintain ongoing dialogue between cancer clinicians, imaging specialists and health-care economists.

Response Evaluation and Survival Prediction After PD-1 Immunotherapy in Patients with Non-Small Cell Lung Cancer: Comparison of Assessment Methods.

Immunotherapy using programmed death-1 blockers is a promising modality for non-small cell lung cancer (NSCLC). Therefore, defining the most accurate response criteria for immunotherapy monitoring is of great importance in patient management. This study aimed to compare the correlation between survival outcome and response assessment by PERCIST, version 1.0; immunotherapy-modified PERCIST (imPERCIST); RECIST, version 1.1; and immunotherapy-modified RECIST (iRECIST) in NSCLC patients. Methods: Seventy-two patients with NSCLC who were treated with nivolumab or pembrolizumab and had baseline and follow-up 18F-FDG PET/CT data were analyzed. The patients were categorized into responders (complete or partial response) and nonresponders (stable or progressive disease) according to PERCIST1 and PERCIST5 (analyzing the peak SUV normalized by lean body mass [SULpeak] of 1 or up to 5 lesions), imPERCIST1, imPERCIST5, RECIST, and iRECIST. The correlation between achieved response and overall survival (OS) was compared. Results: The overall response rate and the overall disease control rate of the study population were 29% and 74%, respectively. The OS and progression-free survival (PFS) of patients with complete and partial response were statistically comparable. The OS and PFS were significantly different between responders and nonresponders (20.3 vs. 10.6 mo, P = 0.001, for OS and 15.5 vs. 2.2 mo, P < 0.001, for PFS, respectively). Twenty-three (32%) patients with progressive disease according to PERCIST5 had controlled disease according to imPERCIST5; follow-up of patients showed that 22% of these patients had pseudoprogression. The overall incidence of pseudoprogression was 7%. The response rate was 25% and 24% according to PERCIST1 and PERCIST5 (P = 0.2) and 32% and 29% according to imPERCIST1 and imPERCIST5 (P = 0.5), respectively, indicating no significant difference between analyzing the SULpeak of only the most 18F-FDG-avid lesion and analyzing up to the 5 most 18F-FDG-avid lesions. Conclusion: The achieved response by all conventional and immunotherapy-modified methods correlated strongly with patients' survival outcome, with significantly longer OS and PFS in responders than in nonresponders according to all assessed definitions. The most 18F-FDG-avid lesion according to PERCIST and imPERCIST accurately reflects the overall metabolic response.

Mycobacterium tuberculosis infection in patients with cancer, the role of 18-fluorodeoxyglucose positron emission tomography for diagnosis and monitoring treatment response.

Active tuberculosis (TB) infection including asymptomatic and extrapulmonary disease may be detected with 18-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT). This report highlights the promising role of FDG-PET/CT for evaluation of TB in high-risk, immunocompromised patients with cancer. PET/CT performed for cancer evaluation may detect asymptomatic infection and guide definitive diagnosis. It may also be a useful tool in the assessment of latent TB, to exclude active disease prior to treatment. PET/CT has potential for monitoring response to anti-tuberculosis treatment. Metabolic response may indicate clinical response and guide duration of anti-microbial therapy.

Clinical experience of the first digital mammographic unit in Australia in its first year of use.

In April 2004, Melbourne's Peter MacCallum Cancer Centre, Australia's only stand-alone dedicated cancer hospital, became the first Australian site to offer digital mammography (DM). In the first year of DM operation, 1208 mammograms were performed on 1157 women; 17 new cases of invasive carcinoma and six new cases of ductal carcinoma-in-situ (DCIS) were detected; and 30 hook-wire needle localisations were conducted in 29 patients. We developed a unit policy to manage indeterminate microcalcifications newly demonstrated on DM that were not previously detected by conventional screen-film mammography (CM): those believed to have malignant morphology were recommended for biopsy, and those without were recommended for 6-month DM follow-up to confirm microcalcification stability. DM detected 56 new stand-alone microcalcifications (18 suspicious and 38 indeterminate). Tissue diagnosis of 12 suspicious microcalcifications yielded four cases of DCIS and one of atypical ductal hyperplasia. Of the indeterminate microcalcifications, 35 have demonstrated stability at DM follow-up to date, over a mean period of 23.6 months. From our experience, we believe DM's superior demonstration ability uncovered microcalcifications previously undetected by CM, rather than microcalcification progression. We suggest that routine review with DM, rather than biopsy, is appropriate management when new indeterminate microcalcifications without malignant characteristics are identified by DM.

Clinical experience with the first combined positron emission tomography/computed tomography scanner in Australia.

Metabolic imaging with fluorine-18-fluorodeoxyglucose positron emission tomography (FDG-PET) is increasing rapidly worldwide because of superior accuracy compared with conventional non-invasive techniques used for evaluating cancer. Limited anatomical information from FDG-PET images alone dictates that complementary use with structural imaging is required to optimise benefit. Recently, combined positron emission tomography/computed tomography (PET/CT) scanners have overtaken standalone PET scanners as the most commonly purchased PET devices. We describe our experience of over 5500 scans performed since the first PET/CT scanner in Australia was commissioned at the Peter MacCallum Cancer Centre (PMCC), Melbourne, in January 2002. Clinical indications for PET/CT scans performed at PMCC largely reflect current Medicare reimbursement policy. Advantages of PET/CT include greater patient comfort and higher throughput, greater diagnostic certainty and accuracy, improved biopsy methods, and better treatment planning. We believe PET/CT will underpin more effective and efficient imaging paradigms for many common tumours, and lead to a decrease in imaging costs.