The current status of an FDG-PET cancer screening program in Japan, based on a 4-year (2006-2009) nationwide survey

Unexpected focal fluorodeoxyglucose uptake in main organs; pass through or pass by?

Since the inception of fluorine-18 fluorodeoxyglucose (F-18 FDG), positron emission tomography/computed tomography (PET/CT) utilizing F-18 FDG has become widely accepted as a valuable imaging modality in the field of oncology, with global prevalence in clinical practice. Given that a single Torso PET/CT scan encompasses the anatomical region from the skull base to the upper thigh, the detection of incidental abnormal focal hypermetabolism in areas of limited clinical interest is both feasible and not uncommon. Numerous investigations have been undertaken to delineate the distinctive features of these findings, yet the outcomes have proven inconclusive. The incongruent results of these studies present a challenge for physicians, leaving them uncertain about the appropriate course of action. This article provides a succinct overview of the characteristics of fluorodeoxyglucose, followed by a comprehensive discussion of the imaging findings and clinical significance associated with incidental focal abnormal F-18 FDG activity in several representative organs. In conclusion, while the prevalence of unrecognized malignancy varies across organs, malignancies account for a substantial proportion, ranging from approximately one-third to over half, of incidental focal uptake. In light of these rates, physicians are urged to exercise vigilance in not disregarding unexpected uptake, facilitating more assured clinical decisions, and advocating for further active evaluation.

[18F]FDG PET/MRI combined with chest HRCT in early cancer detection: a retrospective study of 3020 asymptomatic subjects

PURPOSE

PET/MRI has become an important medical imaging approach in clinical practice. In this study, we retrospectively investigated the detectability of fluorine-18 (18F)-fluorodeoxyglucose positron emission tomography/magnetic resonance imaging ([18F]FDG PET/MRI) combined with chest computerized tomography (CT) for early cancer in a large cohort of asymptomatic subjects.

METHODS

This study included a total of 3020 asymptomatic subjects who underwent whole-body [18F]FDG PET/MRI and chest HRCT examinations. All subjects received a 2-4-year follow-up for cancer development. Cancer detection rate, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the [18F]FDG PET/MRI with or without chest HRCT were calculated and analyzed.

RESULTS

Sixty-one subjects were pathologically diagnosed with cancers, among which 59 were correctly detected by [18F]FDG PET/MRI combined with chest HRCT. Of the 59 patients (32 with lung cancer, 9 with breast cancer, 6 with thyroid cancer, 5 with colon cancer, 3 with renal cancer, 1 with prostate cancer, 1 with gastric cancer, 1 with endometrial cancer, and 1 with lymphoma), 54 (91.5%) were at stage 0 or stage I (according to the 8th edition of the tumor-node-metastasis [TNM] staging system), 33 (55.9%) were detected by PET/MRI alone (27 with non-lung cancers and 6 with lung cancer). Cancer detection rate, sensitivity, specificity, PPV, and NPV for PET/MRI combined with chest CT were 2.0%, 96.7%, 99.6%, 83.1%, and 99.9%, respectively. For PET/MRI alone, the metrics were 1.1%, 54.1%, 99.6%, 73.3%, and 99.1%, respectively, and for PET/MRI in non-lung cancers, the metrics were 0.9%, 93.1%, 99.6%, 69.2%, and 99.9%, respectively.

CONCLUSIONS

[18F]FDG PET/MRI holds great promise for the early detection of non-lung cancers, while it seems insufficient for detecting early-stage lung cancers. Chest HRCT can be complementary to whole-body PET/MRI for early cancer detection.

TRIAL REGISTRATION

ChiCTR2200060041. Registered 16 May 2022. Public site: https://www.chictr.org.cn/index.html.

Significance of incidental focal fluorine-18 fluorodeoxyglucose uptake in colon/rectum, thyroid, and prostate: With a brief literature review

BACKGROUND

Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (F-18 FDG PET/CT), a functional imaging method, is usually performed on the entire torso, and regions of unexpected suspicious focal hypermetabolism are not infrequently observed. Among the regions, colon, thyroid, and prostate were found to be the common organs in a recent umbrella review. Some studies reported that a high rate of malignancy was shown in incidentally identified focal hypermetabolic regions and suggested that further examinations should not be ignored.

AIM

To investigate the malignancy rate of incidental focal FDG uptake, useful PET parameters and their cutoffs in discrimination between malignant and benign lesions.

METHODS

Retrospectively, the final reports of 16510 F-18 FDG PET/CT scans performed at our hospital between January 2016 and March 2022 were reviewed to identify incidentally observed FDG uptake in the colon/rectum, thyroid, and prostate. The scans of patients with current or prior malignancies at each corresponding location, without the final reports of histopathology or colonoscopy (for colon and rectum) for the corresponding hypermetabolic regions, or with diffuse (not focal) hypermetabolism were excluded. Finally, 88 regions of focal colorectal hypermetabolism in 85 patients (48 men and 37 women with mean age 67.0 ± 13.4 years and 63.4 ± 15.8 years, respectively), 48 focal thyroid uptakes in 48 patients (12 men and 36 women with mean age 62.2 ± 13.1 years and 60.8 ± 12.4 years, respectively), and 39 focal prostate uptakes in 39 patients (mean age 71.8 ± 7.5 years) were eligible for this study. For those unexpected focal hypermetabolic regions, rates of malignancy were calculated, PET parameters, such as standardized uptake value (SUV), capable of distinguishing between malignant and benign lesions were investigated, and the cutoffs of those PET parameters were determined by plotting receiver operating characteristic curves.

RESULTS

In the colon and rectum, 29.5% (26/88) were malignant and 33.0% (29/88) were premalignant lesions. Both SUVmax and SUVpeak differentiated malignant/premalignant from benign lesions, however, no parameters could distinguish malignant from premalignant lesions. Higher area under the curve was shown with SUVmax (0.752, 95%CI: 0.649-0.856, P < 0.001) and the cutoff was 7.6. In the thyroid, 60.4% (29/48) were malignant. The majority were well-differentiated thyroid cancers (89.7%, 26/29). The results of BRAF mutation tests were available for 20 of the 26 well-differentiated thyroid cancers and all 20 had the mutation. Solely SUVmax differentiated malignant from benign lesions and the cutoff was 6.9. In the prostate, 56.4% (22/39) were malignant. Only SUVmax differentiated malignant from benign lesions and the cutoff was 3.8. Overall, among the 175 focal hypermetabolic regions, 60.6% (106/175) were proven to be malignant and premalignant (in colon and rectum) lesions.

CONCLUSION

Approximately 60% of the incidentally observed focal F-18 FDG uptake in the colon/rectum, thyroid, and prostate were found to be malignant. Of the several PET parameters, SUVmax was superior to others in distinguishing between malignant/premalignant and benign lesions. Based on these findings, incidental focal hypermetabolism should not be ignored and lead physicians to conduct further investigations with greater confidence.

Fluorine-18 Labeled Urea-Based Ligands Targeting Prostate-Specific Membrane Antigen (PSMA) with Increased Tumor and Decreased Renal Uptake

High expression of prostate-specific membrane antigen (PSMA) in prostate cancers prompted the development of the PSMA-targeted PET-imaging agent [18F]DCFPyL, which was recently approved by the FDA. Fluorine-18-labeled Lys–Urea–Glu-based oxime derivatives of [18F]DCFPyL were prepared for the comparison of their in vitro and in vivo properties to potentially improve kidney clearance and tumor targeting. The oxime radiotracers were produced by condensation of an aminooxy functionalized PSMA-inhibitor Lys–Urea–Glu scaffold with fluorine-18-labeled aldehydes. The radiochemical yields were between 15–42% (decay uncorrected) in 50–60 min. In vitro saturation and competition binding assays with human prostate cancer cells transfected with PSMA, PC3(+), indicated similar high nM binding affinities to PSMA for all radiotracers. In vivo biodistribution studies with positive control PC3(+) tumor xenografts showed that the kidneys had the highest uptake followed by tumors at 60 min. The PC3(+) tumor uptake was blocked with non-radioactive DCFPyL, and PC3(−) tumor xenograft (negative control) tumor uptake was negligible indicating that PSMA targeting was preserved. The most lipophilic tracer, [18F]2a, displayed comparable tumor-targeting to [18F]DCFPyL and a desirable alteration in pharmacokinetics and metabolism, resulting in significantly lower kidney uptake with a shift towards hepatobiliary clearance and increased liver uptake.

Change in cancer diagnosis during the COVID-19 pandemic: Trends estimated from FDG-PET/CT

The aim of this study is to clarify changes in the circumstances of cancer diagnoses during the COVID-19 pandemic in Tokyo, Japan, estimated from [¹⁸F]-2-fluoro-2-deoxy-D-glucose (FDG) -positron emission tomography/ computed tomography (PET/CT) for cancer patients. Cancer diagnosis in pandemic status (PANS) was evaluated by retrospective review of the findings of FDG-PET/CT examinations performed between 11 March 2020 and 28 December 2021 for initial staging and restaging for malignancy. Evaluation of cancer diagnosis in pre-pandemic status (pPANS) was conducted similarly in FDG-PET/CT examinations performed between 4 January 2018 and 10 March 2020. Of these, patients with malignant lymphoma (ML), lung cancer, esophageal cancer, and colorectal cancer who had a pathologically proven diagnosis or clinical diagnosis following therapy of the disease were selected for analysis. Initial cancer staging was determined by the diagnostic report of FDG-PET/CT. Change in cancer stage and in the number of FDG-PET/CT examinations performed was evaluated between pPANS and PANS, and according to term of the pandemic and vaccination status. The COVID-19 epidemic influenced the number of cancer patients who underwent FDG-PET/CT. There was a marked decrease in the number of cancer patients receiving FDG-PET/CT in Terms 1-3 (March 2020 to February 2021), but it recovered in Terms 4-6 (March 2021 to December 2021). There was no significant difference between PANS and pPANS in terms of the initial stage of cancer, but Stage IV ML and Stage II esophageal cancer were more frequent in PANS. Initial staging of ML, lung cancer, and esophageal cancer revealed more advanced cancer stages in Terms 4-6 compared with Terms 1-3. The number of patients receiving FDG-PET/CT in Tokyo was influenced by the COVID-19 epidemic. Staging based on FDG-PET/CT shifted to more advanced cancer stage during the pandemic compared with pre-pandemic.

Beyond the Prognostic Value of 2-[18F]FDG PET/CT in Prostate Cancer: A Case Series and Literature Review Focusing on the Diagnostic Value and Impact on Patient Management

The role of 2-deoxy-2-[¹⁸F]fluoro-D-glucose Positron Emission Tomography/Computed Tomography (FDG PET/CT) in the management of prostate cancer (PCa) patients is increasingly recognised. However, its clinical role is still controversial. Many published studies showed that FDG PET/CT might have a prognostic value in the metastatic castration-resistant phase of the disease, but its role in other settings of PCa and, more importantly, its impact on final clinical management remains to be further investigated. We describe a series of six representative clinical cases of PCa in different clinical settings, but all characterised by a measurable clinical impact of FDG PET/CT on the patients’ management. Starting from their clinical history, we report a concise narrative literature review on the advantages and limitations of FDG PET/CT beyond its prognostic value in PCa. What emerges is that in selected cases, this imaging technique may represent a useful tool in managing PCa patients. However, in the absence of dedicated studies to define the optimal clinical setting of its application, no standard recommendations on its use in PCa patients can be made.

Changes of 18 F-fluoro-2-deoxyglucose position-emission tomography findings by the eradication of Helicobacter pylori in the stomach

PURPOSE

Helicobacter pylori (HP) infection is reported to increase ¹⁸ F-fluoro-2-deoxyglucose (FDG) accumulation in the stomach. The accumulation of FDG by positron-emission tomography (FDG-PET) in the stomach for the voluntary health examinees of cancer checkup was examined before and after the HP eradication.

SUBJECTS AND METHODS

From March 2013 to October 2015, eighty-one subjects were performed FDG-PET to detect cancer at the health checkup. All of them were also surveyed by esophagogastroduodenoscopy. Subjects were classified as the 33 cases of HP positive (group A), 38 cases of originally negative (group B), and the 10 negative cases by HP eradication therapy (group C). Group A was treated by combination of amoxicillin, clarithromycin, and proton pump inhibitor for a week, and all of them eradicated HP. A part of group A (n = 7) was serially performed FDG-PET one to five years after the treatment and compared the maximum standard uptake value of FDG (SUV) around the fundic gland region.

RESULTS

SUV of group A (3.55 ± 0.69) was significantly higher than those of both group B (2.96 ± 0.72) and group C (2.89 ± 0.51) (p < 0.01, respectively). Groups B and C are almost comparable and showed no significant difference during the course. In group A, HP eradication significantly decreased the SUV to 3.1 ± 0.43 (P < .01). SUV after the eradication was significantly reduced (P < .01) in the mild to moderate atrophy (C1-C3) group according to Kimura and Takemoto classification of chronic gastritis of group A. Although SUV in the advanced atrophy group (O1-O3) tended to decline after the eradication, the change was not significant.

CONCLUSION

HP-infected stomach showed higher FDG uptake in the fundic gland region and HP eradication decreased the uptake in the mild to moderate atrophic gastritis but not in the severe atrophic gastritis.

Prospective Employer-Initiated Whole-Body Cancer Screening-Costs and Outcomes of a Cancer Screening Program in Japan

PURPOSES

To determine cancer detection and mortality and its costs associated with employee-initiated, prospective whole-body cancer screening program in an engineering company in Hamamatsu, Japan.

MATERIALS AND METHODS

The program includes whole-body fluorine-18-2-fluoro-2-deoxy-D-glucose PET/CT, brain and pelvis MR, and abdominal ultrasound, offered every 2 years five consecutive times. Employees are free to opt in or opt out anytime. The subjects were divided into the full (five consecutive screenings), partial (more than once and less than five), and no participation groups. The rate ratio of cancer detection rate and cancer-related mortality and cancer-related costs of care were measured. All employees also received other annual health screenings, including chest radiograph or upper gastrointestinal study.

RESULTS

Among 1,213 subjects, 543 employees were under full participation, 318 were under partial participation, and 352 were under no participation. In all, 26, 9, and 19 cancers were detected from the full participation, partial participation, and nonparticipation groups, respectively. No statistical significance was observed in the cancer detection rate ratio. The rate ratio of cancer-related deaths was 0.11 (0.01-0.90) for the full participation group compared with the nonparticipation group, and the difference was statistically significant. The cost of cancer-related care was highest among the nonparticipation group; however, the difference was not statistically significant (P = .108).

CONCLUSION

Whole-body cancer screening can successfully reduce cancer-related mortality and costs of cancer-related care. The cancer detection rate was not significantly improved because of broad implementation of additional annual health screenings offered to all employees at no cost, resulting in the high baseline cancer detection rate.

Prevalence of Newly Diagnosed Malignancies in Patients with Polymyalgia Rheumatica and Giant Cell Arteritis, Comparison of 18F-FDG PET/CT Scan with Chest X-ray and Abdominal Ultrasound: Data from a 40 Week Prospective, Exploratory, Single Centre Study

The aim of the study was to identify the prevalence of newly diagnosed malignancies in patients with polymyalgia rheumatica (PMR) and giant cell arteritis (GCA), with the aid of 18F-FDG PET/CT scan compared to conventional imaging techniques: Chest X-ray (CXR) and abdominal ultrasound (US). Secondarily, to examine the relative diagnostic accuracy of these two imaging modalities for the detection of cancer. Eighty consecutive patients with newly diagnosed PMR, GCA, or concomitant PMR and GCA, were included and followed up for 40 weeks. All patients underwent an 18F-FDG PET/CT scan, CXR, and abdominal US at diagnosis. Imaging findings were dichotomously categorized into malignant or benign. Among 80 patients, three patients were diagnosed with seronegative rheumatoid arthritis and were excluded from the analysis. Of the remaining 77, 64 (83.1%) patients were diagnosed with pure PMR, 3 (3.9%) with pure GCA, and 10 (13.0%) with concomitant PMR and GCA. Five types of cancer that were more prevalent than the one-year prevalence of 1.2% among the background population were found in four (5.2%; 95%CI: 1.4-12.8%) patients. CXR/abdominal US could detect the solid cancer in one patient, whereas 18F-FDG PET/CT could identify all four solid cancers. Furthermore, four (5.2%; 95%CI: 1.4-12.8%) cases of monoclonal gammopathy of undetermined significance (MGUS) were found. An increase in C reactive protein (CRP) implicated an increased risk for cancer of 2.4% (OR: 1.024, 95%CI: 1.001-1.047; p = 0.041). 18F-FDG PET/CT can reveal occult cancers at an early stage with a high negative predictive value, and it is specifically beneficial in PMR/GCA patients with nonspecific symptoms.

Limited usefulness of serum carcinoembryonic antigen and carbohydrate antigen 19-9 levels for gastrointestinal and whole-body cancer screening

The diagnostic performance of serum carcinoembryonic antigen (CEA) and carbohydrate antigen (CA) 19-9 levels for multiple-organ cancer screening has not been fully elucidated. However, they are widely used for real-world opportunistic screening of multiple-organ cancers. This study aimed to examine the diagnostic performance of these serum markers in multiple-organ cancer screening. Data from asymptomatic individuals subjected to opportunistic cancer screening were analyzed. The diagnostic performance of CEA and CA 19-9 was assessed for (A) upper/lower gastrointestinal cancers and (B) whole-body cancers (including both gastrointestinal and other organ cancers) using the results of upper/lower gastrointestinal endoscopy and whole-body imaging as reference. Data from 12,349 and 7616 screened individuals were used to assess the diagnostic performance of CEA and CA 19-9 for (A) and (B), respectively. For (A), the sensitivity and positive predictive value (PPV) of CEA (cut-off: 5 ng/mL) were 7.8% and 3.7%, respectively; those of CA19-9 (cut-off: 37 U/mL) were 7.4% and 2.7%, respectively. For (B), the sensitivity and PPV of CEA were 6.6% and 4.1%, respectively, and those of CA19-9 were 10.8% and 5.8%, respectively. Considering even multiple cancers, the sensitivity and PPV of CEA and CA 19-9 were low, thus confirming their limited usefulness in multiple-organ cancer screening.

FDG-PET/CT Incidental Detection of Cancer in Patients Investigated for Infective Endocarditis

Background: Fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) is an imaging technique largely used in the management of infective endocarditis and in the detection and staging of cancer. We evaluate our experience of incidental cancer detection by PET/CT during IE investigations and follow-up.

Methods and Findings: Between 2009 and 2018, our center, which includes an “endocarditis team,” managed 750 patients with IE in a prospective cohort. PET/CT became available in 2011 and was performed in 451 patients. Incidental diagnosis of cancer by PET/CT was observed in 36 patients and confirmed in 34 of them (7.5%) (colorectal n = 17; lung n = 7; lymphoma n = 2; melanoma n = 2; ovarian n = 2; prostate n = 1; bladder n = 1; ear, nose, and throat n = 1; brain n = 1). A significant association has been found between colorectal cancer and Streptococcus gallolyticus and/or Enterococcus faecalis [12/26 vs. 6/33 for other cancers, p = 0.025, odds ratio = 3.86 (1.19–12.47)]. Two patients had a negative PET/CT (a colon cancer and a bladder cancer), and two patients, with positive PET/CT, had a benign colorectal tumor. PET/CT had a sensitivity of 94–100% for the diagnosis of cancer in this patient.

Conclusions: Whole-body PET/CT confirmed the high incidence of cancer in patients with IE and could now be proposed in these cases.

Molecular imaging of prostate cancer: Review of imaging agents, modalities, and current status

INTRODUCTION

The clinical course of Prostate cancer (PCa) are markedly diverse, ranging from indolent to highly aggressive disseminated disease. Molecular imaging techniques are playing an increasing role in early PCa detection, staging and disease recurrence. There are some molecular imaging modalities, radiotracers agents and its performance are important in current clinical practice PCa.

OBJECTIVE

This review summarizes the latest information regarding molecular imaging of PCa and is designed to assist urologists with ordering and interpreting these modalities and different radiotracers for different patients.

EVIDENCE ACQUISITION

A PubMed-based literature search was conducted up to September 2019. We selected the most recent and relevant original articles, metanalysis and reviews that have provided relevant information to guide molecular imaging modalities and radiotracers use.

EVIDENCE SYNTHESIS

In this review, we discuss 3 main molecular imaging modalities and 7 radiotracer technologies available.

CONCLUSIONS

The use molecular imaging modalities and radiotracers has a unique role in biochemical recurrence and diagnosis of ganglionar and bone progression of PCa. In the present time, no one of these molecular imaging modalities can be recommended over the classical work-up of abdominopelvic CT scan and bone scan, and large-scale and multi-institutional studies are required to validate the efficacy and cost utility of these new technologies.

Ten-year prospective evaluation of whole-body cancer screening with multiple modalities including [18F]fluorodeoxyglucose positron emission tomography in a healthy population

PURPOSE

To prospectively evaluate the value of whole-body cancer screening with multiple modalities including FDG-PET in a healthy population.

METHODS

The study was conducted in 1197 healthy individuals aged ≥ 35 years at enrollment between August 2003 and July 2004. All participants were scheduled to receive annual whole-body cancer screening five times (screening period) with subsequent long-term follow-up (follow-up period). The endpoints of the study were definitive cancer diagnosis, cancer-related death, and all-cause death.

RESULTS

The follow-up rate was 99.8% for the screening period and 96.2% for the follow-up period. Forty-five cancers were confirmed during the screening period (August 2003 to July 2009), and 37 of the 45 were detected by the screening. Fourteen of the 45 were PET positive. Sixteen, 5, 4, 9 and 11 cancers were confirmed after the first, the second, the third, the fourth, and the fifth (took 2 years) screening, respectively. Eight participants died, of whom five died of cancer. The rate of cancer incidence (per 100,000) of 628.7 (95% confidence interval [CI] 445.0-812.4) was significantly high, and the rates of cancer mortality and all-cause mortality of 69.9 (95% CI 8.6-131.1) and 111.8 (95% CI 34.3-189.2), respectively, were significantly low, compared with the corresponding rates of 379.3, 138.2 and 354.2, respectively, in the age-rank- and sex-matched general population. During the follow-up period (August 2009 to July 2013), 37 cancers were confirmed and 30 of the 37 were detected. Seven participants died, of whom three died of cancer. The rate of cancer incidence was 809.6 (95% CI 548.7-1070.5). The rates of cancer mortality and all-cause mortality of 65.6 (95% CI 0-139.9) and 153.2 (95% CI 39.7-266.6), respectively, were significantly low compared with 190.1 and 462.3, respectively, in the general population.

CONCLUSION

Cancer detection by PET alone was limited. While the high cancer incidence was attributed to the extensive screening, the low cancer and all-cause mortality may indicate the potential value of this type of cancer screening. Cancer incidence increases with aging and it has been shown that continuous screening may reduce the risk caused by the cancer progression.

Melanoma Radiological Surveillance: A Review of Current Evidence and Clinical Challenges

Melanoma is a common cancer in both young and older populations in many western countries. Rates of melanoma diagnosis worldwide are increasing. With the introduction of both targeted and immunotherapies there have been dramatic improvements in the care of patients with metastatic melanoma. With these new therapies being increasingly offered to patients with stage III metastatic melanoma and stage IV disease, radiological surveillance of melanoma has become a widely used method of monitoring melanoma patients for early locoregional and distant metastasis. However, concerns have been raised about risk of false positive results, which patients to consider radiological surveillance for, and at what intervals to do so. To date, there are no published review articles on the topic of radiological surveillance in melanoma patients identified in the MEDLINE database. A comprehensive literature review was performed by searching the MEDLINE database to review all published works on this topic. This article aims to present an extensive review of literature surrounding radiological surveillance in melanoma patients, a discussion of controversies, and recommendations for surveillance modalities.

Clinical usefulness of FDG-PET/CT for identification of abnormal extra-cardiac foci in patients with infective endocarditis

The aim of the study was to evaluate the ability to detect extra-cardiac foci by means of whole-body ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) in patients with definite endocarditis (IE) according to the modified Duke criteria and investigate the clinical impact of the findings. From January 2011 to December 2015 we included 178 patients (mean age 66 ± 14 years, 25% female) with IE in this multicentre study. FDG-PET/CT was part of the work-up for extra-cardiac foci in the including hospitals and was performed at a median of 9 days (IQR 10) after IE was diagnosed. In 114 patients FDG-PET/CT identified 166 lesions: 52 (31%) infectious lesions, 21 (13%) cases of cancer, 7 (4%) cases of embolism, 60 (36%) reactive findings, and 26 (16%) other types of lesions. A total of 74 new extra-cardiac findings, not previously discovered by other modalities, were identified in 62 patients and resulted in additional investigations in 29 patients and a change in treatment in 18 patients (10%). The most frequent diagnoses discovered by FDG-PET/CT were colon polyps, cancer, and spondylodiscitis. There was a higher rate of findings leading to a change in treatment in patients above 67 years of age infected with other bacterial aetiologies than streptococci. FDG-PET/CT was useful to detect extra-cardiac foci. FDG-PET/CT findings may lead to unnecessary investigations. One out of 10 the patients with definite endocarditis had underwent a change in treatment regimen based on the FDG-PET/CT findings.

Comparative prognostic implication of treatment response assessments in mCRPC: PERCIST 1.0, RECIST 1.1, and PSA response criteria

Accurate appraisal of treatment response in metastatic castrate-resistant prostate cancer (mCRPC) is challenging in view of remarkable tumor heterogeneity and the available choices among many established and novel therapeutic approaches. The purpose of this single-center prospective study was to evaluate the comparative prognostic utility of PERCIST 1.0 in predicting overall survival (OS) in patients with mCRPC compared to RECIST 1.1 and prostate-specific antigen (PSA)-based treatment response assessments.

Methods: Patients with mCRPC were prospectively enrolled if they were beginning systemic medical therapy or transitioning to new systemic therapy after not responding to a prior treatment. All patients underwent a baseline ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography/ computed tomography (PET/CT) prior to the initiation of treatment and again 4 months after the start of therapy. Patients' responses to treatment at 4 months compared to baseline were evaluated with RECIST 1.1, PERCIST 1.0 and PSA response criteria. The associations between patients' response categories and OS were evaluated. OS was defined as the duration in time between the date of baseline PET/CT to death from any cause. Patients with different response status were compared with logrank tests. Survival probabilities were calculated using the Kaplan-Meier method.

Results: Patients with progressive disease by PSA response criteria at 4 months demonstrated significantly shorter OS (24-month OS probability: 18% ± 11%) compared to patients with stable disease, SD, (44% ± 19%, p=0.03) and complete response, CR, or partial response, PR, (53% ± 11%, p=0.03). RECIST 1.1 response criteria demonstrated a similar trend in OS, however no statistically significant differences were noted between patients with PD (25% ± 15%) compared to SD/non-CR, non-PD (54% ± 13%) and CR/PR (54% ± 14%) (p=0.13). PERCIST 1.0 criteria demonstrated significant differences in OS between responders, CMR/PMR (56% ± 12%), compared to SMD (38% ± 17%, p=0.03) and PMD (21% ± 10%, p=0.01). Patients with progressive disease by both PERICST 1.0 and PSA response criteria demonstrated significantly worse OS (24-month OS: 0%, 12-month OS: 31% ± 14%) compared to patients with progressive disease by either response criteria.

Conclusion: PERCIST 1.0 may provide significant prognostic information for patients with mCRPC undergoing systemic chemotherapy, particularly when incorporated with PSA treatment response criteria.

Comparison of FDG-PET/CT for Cancer Detection in Populations With Different Risks of Underlying Malignancy

Background/Aim: Whole-body positron-emission tomography/computed tomography with the glucose analog 2-[ 18 F]fluoro-2-deoxy-D-glucose (FDG-PET/CT) has been used to screen examinees for underlying malignancy in many countries. The aim of this study was to compare the potential value of FDG-PET/CT application in asymptomatic individuals with those with suspected malignancy. Patients and Methods: A total of 9,408 examinees underwent whole-body FDG-PET/CT at our hospital from July 2006 to August 2013. Three thousand and seven hundred asymptomatic individuals and 848 individuals with laboratory and clinical/radiologicaI suspicion of malignancy who had undergone FDG-PET/CT for cancer screening were recruited. The final confirmation of cancer and outcomes were based on a pathological report and continuous follow-up. Results: Forty-five out of 3,700 asymptomatic individuals (1.2%) had proven malignancy, and 42 of them (93.3%) were found by FDG-PET/CT. Two hundred and twelve out of 848 with suspected malignancy (25%) had proven malignancy, and 196 of them (92.5%) were detected by FDG-PET/CT. Most of these cancers in asymptomatic individuals were clinically at an early stage. The discovery rate in asymptomatic individuals and those with suspected malignancy was 1.1% and 23.1%, respectively. The overall survival of patients with cancer diagnosed with PET/CT was higher than those with suspected malignancy (78.6% vs. 48.5%, p<0.001). Patients with a resectable lesion, early-stage disease, and lower maximal standardized uptake value had significantly better survival than those without. Conclusion: FDG-PET/CT is useful in the early diagnosis of cancer and thus might improve the survival rates of these patients. Considering the costs and risk of radiation exposure, it would be better used as a priority in patients with laboratory and clinical/radiologic suspicion of malignancy.

Non-AIDS-defining malignancies in Japanese hemophiliacs with HIV-1 infection

Along improvement of prognosis of HIV-1-infected patients due to successful anti-retroviral therapy, main causes of death in the patients have been changing from AIDS to non-AIDS defining malignancies (NADM) recently. However, little is known about the prevalence and incidence of NADM in patients, and especially in HIV-1-infected hemophiliacs. We prospectively conducted NADM screening with FDG-PET, chest CT, upper gastrointestinal endoscopy, tumor markers, and stool occult blood in hemophiliacs with a mean age of 48.9 years. Screening was done twice from December 2016 through March 2019; the first screening was used to calculate prevalence in 69 patients and the second was used to calculate incidence in 56 patients. The first screening revealed 4 cases of malignancies; three were cases of thyroid cancer and one was a case of a neuroendocrine tumor in the pancreas; prevalence was 5.8% (95% CI: 0.2-11.4%). During a mean follow-up of 1.2 years with 68.2 person-years (PYs), cancer was diagnosed in 2 cases (pancreatic and liver cancer) during the second screening. Incidence was 2.99/100 PY. It can be speculated that there might be around 40 cases of undiagnosed NADM currently and 20 cases of new NADM annually in this population, because 718 HIV-1-infected hemophiliacs are surviving in Japan according to the 2018 Nationwide Survey on Coagulation Disorders. Screening for NADM in HIV-1-infected hemophiliacs at other hospitals is strongly recommended.

Incidentally Detected 18F-FDG-Avid Prostate Cancer Diagnosed Using a Novel Fusion Biopsy Platform

Background: Localized prostate cancer rarely undergoes a shift in metabolism towards aerobic glycolysis, a process known as the Warburg Effect. Because of this, positron emission tomography (PET)/CT imaging using 2-deoxy-2-[¹⁸F]fluoro-d-glucose (¹⁸F-FDG) is uncommonly used to evaluate patients with early-stage prostate cancer. However, men undergoing an ¹⁸F-FDG PET/CT for unrelated reasons will on occasion be found to have radiotracer uptake within the prostate gland. The appropriate work-up of these patients is poorly defined. Case Presentation: We present the case of a 61-year-old man with a history of tonsillar squamous cell carcinoma who was incidentally found on ¹⁸F-FDG PET/CT to have a hypermetabolic nodule within the prostate. The patient's prostate-specific antigen level was 2.1 ng/cc and digital rectal examination revealed no abnormalities. The patient underwent a targeted prostate biopsy of the lesion using the KOELIS Trinity biopsy platform, which uniquely allows for the real-time overlay of transrectal ultrasonography and PET/CT images. Targeted biopsy revealed Gleason score 4 + 3 = 7 (grade group 3) prostate cancer. Conclusion: Although the incidental detection of ¹⁸F-FDG uptake within the prostate is uncommon, more than half of all patients will be found to have prostate cancer. Based on this case and our review of the available medical literature, it is our belief that men with incidentally detected uptake of ¹⁸F-FDG within the prostate should undergo further evaluation with a prostate biopsy. This recommendation is supported by data suggesting that ¹⁸F-FDG-avid prostate cancer represents a more aggressive clinical phenotype.

Standardized Uptake Value Using Thyroid Quantitative SPECT/CT for the Diagnosis and Evaluation of Graves' Disease: A Prospective Multicenter Study

The clinical applications of the quantitative single photon emission computed tomography (SPECT)/computed tomography (CT) are being expanded to a variety of fields of nuclear medicine. However, clinical application of quantitative SPECT/CT for the evaluation of Graves' disease (GD) still needs further investigation. Our aim was to investigate the feasibility of standard uptake value (SUV) of the thyroid for the clinical diagnosis and evaluation of GD. In this prospective multicenter study, 116 patients diagnosed with GD (Graves group) and 74 healthy volunteers (control group) were enrolled from 8 different hospitals. All patients underwent technetium pertechnetate (^99mTcO₄ ^-) SPECT/CT imaging with Q.Metrix quantitative software and 24-hour thyroid radioactive iodine uptake (24h-RAIU) test. The SUVmax and SUVmean in Graves group were significantly higher than those of control group (P<0.01). Cut-off values of SUVmax and SUVmean to predict GD were 231.425 and 116.66 by ROC curves, respectively. The SUVmax and SUVmean in Graves patients were significantly related to serum thyroxine level with correlation coefficient of 0.493 and 0.512 for FT₃ and 0.449 and 0.464 for FT₄, respectively (all P<0.01). Additionally, the SUVmax and SUVmean in GD positively correlated with 24h-RAIU with a coefficient of 0.832 and 0.830, respectively (P<0.01). The volumes determined by Q.Metrix (35.65 ± 20.56ml) of 72 subjects also positively correlated with that from ultrasound (36.67 ± 21.00ml) with a coefficient of 0.927 (P<0.01). SUV measurements derived from thyroid SPECT/CT may be useful for the clinical diagnosis and evaluation of GD.

Sub-clinical abnormalities detected by PET/MRI in household tuberculosis contacts

Background

The understanding of early events following TB exposure is limited by traditional tests that rely on detection of an immune response to infection, which is delayed, or on imaging tests with low sensitivity for early disease. We investigated for evidence of lung abnormalities in heavily exposed TB contacts using PET/MRI.

Methods

30 household contacts of 20 index patients underwent clinical assessment, IGRA testing, chest x-ray and PET/MRI scan using 18-F-FDG. MRI images were examined by a radiology/nuclear medicine dual-qualified physician using a standardised report form, while PET/MRI images were examined independently by another radiology/nuclear medicine dual-qualified physician using a similar form. Standardised uptake value (SUV) was quantified for each abnormal lesion.

Results

IGRA was positive in 40%. PET/MRI scan was abnormal in 30%, predominantly FDG uptake in hilar or mediastinal lymph nodes and lung apices. We did not identify any relationship between PET/MRI findings and degree of exposure or IGRA status.

Conclusion

PET-based imaging may provide important insights into the natural history following exposure to TB that may not be available from traditional tests of TB immune response or imaging. The clinical significance of the abnormalities is uncertain and merits further investigation in longitudinal studies.

Usefulness of both PET/CT with F18-FDG and whole-body diffusion-weighted imaging in cancer screening: a preliminary report

OBJECTIVE

Positron emission tomography/computed tomography (PET/CT) with fluorodeoxyglucose (F18-FDG) is useful for the detection of malignant lesions, including metastatic lesions, and this technique is widely used in cancer screening. However, this approach may occasionally yield false-positive and false-negative findings. At our PET center, to increase the accuracy of PET/CT, we use PET/CT and whole-body diffusion-weighted imaging (WB-DWI) together. This study aimed to assess the usefulness of this combination.

METHODS

We examined 29 subjects with confirmed diagnosis. All of them had undergone PET/CT and WB-DWI on the same day. Twenty-seven of them also underwent ultrasonography, blood testing, and upper gastrointestinal series on the same day and two fecal occult blood tests on another day. WB-DWI was performed on a 1.5-T MRI unit with a b value of 0 and 800 or 1000 s/mm². For all 29 cases, PET/CT and WB-DWI were classified to be positive or negative, and the diagnostic ability was calculated for each modality.

RESULTS

Among the 29 subjects, 17 had malignant tumors and 12 had benign tumors or no abnormalities. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of PET/CT were 65%, 25%, 55%, 33%, and 48%, respectively; while the corresponding values for WB-DWI were 59%, 100%, 100%, 63%, and 76%, respectively. By considering the result to be negative when PET/CT findings were positive but WB-DWI findings were negative, specificity increased from 25 to 100%, and accuracy increased from 48 to 76%. On the other hand, by considering the result to be positive when the findings of either PET/CT or WB-DWI were positive, sensitivity increased from 65 to 76%, and accuracy increased from 48 to 55%.

CONCLUSIONS

Our results suggest that using both PET/CT and WB-DWI together can increase accuracy in cancer screening. However, this approach was not able to detect malignant lesions in some cases, indicating that there were limitations with imaging certain organs. Therefore, it is important to further understand the features of PET/CT and WB-DWI and use them appropriately for each organ. Additionally, given that the study sample was relatively small, further research is needed to validate these findings.

PET/CT incidental detection of second tumor in patients investigated for pancreatic neoplasms

BACKGROUND

Positron Emission Tomography/computed tomography (PET/CT) is an imaging technique which has a role in the detection and staging malignancies (both in first diagnosis and follow-up). The finding of an unexpected region of FDG (Fluorodeoxyglucose) uptake can occur when performing whole-body FDG-PET, raising the possibility of a second primary tumor. The aim of this study was to evaluate our experience of second primary cancer incidentally discovered during PET/CT examination performed for pancreatic diseases, during the initial work-up or follow-up after surgical resection.

METHODS

In this study, a retrospective evaluation of a prospectively collected data base was performed. Three hundred ninety- nine patients with pancreatic pathology were evaluated by whole body PET/CT imaging from January 2004 to December 2014. Among them, 348 patients were scanned before surgical resection and 51 during the course of their follow-up (pancreatic cancer). Median follow-up time was 29 months (range 14-124).

RESULTS

Fifty-six patients (14%) had incidental uptake of FDG in their organs: 31 patients had focal uptake and 25 showed diffuse with or without focal uptake. All patients with focal uptake were investigated, and invasive malignancy was diagnosed in 22 patients: 14 colon, 4 lung, 1 larynx, 1 urothelial, 1 breast cancer, and 1 colon metastasis from pancreatic cancer. Twenty patients underwent resection, and 6 endoscopic removal of colonic polyps. Three patients were not operated for advanced disease, and two patients did not show any pathology (PET/CT false positive). Of the 10 patients investigated for diffuse uptake, no malignancy was found; none of these patients developed a second cancer during the follow-up.

CONCLUSIONS

As in other malignancies, unexpected FDG uptake can occur in patients having PET/CT investigation for pancreatic diseases. Focal uptake is likely to be a malignancy and deserves further investigations, although the stage and the poor prognosis of primary pancreatic cancer should be kept in mind. Some selected patients may benefit from the aggressive treatment of incidental lesions and show survival benefit.

Clinical significance of patterns of increased [18F]-FDG uptake in the thyroid gland: a pictorial review

In the diagnosis and staging of oncologic patients, [¹⁸F]-fluorodeoxyglucose positron emission tomography (FDG-PET) is well recognized as an important functional imaging modality. FDG-PET also has been used for cancer screening in healthy individuals. In general, the normal thyroid gland shows absent or low uptake on FDG-PET, which is often identified as an incidental finding on PET. Today, thyroid FDG uptake can be seen in three patterns: diffuse; focal; and diffuse-plus-focal. Diffuse thyroid uptake is mainly considered an indicator of chronic thyroiditis. Focal thyroid uptake has been associated with malignancy (range 25-50%). Diffuse-plus-focal uptake is not well recognized and might also indicate a risk of malignancy. Understanding the patterns of thyroid FDG uptake is thus important for nuclear medicine physicians or radiologists when giving recommendations to the referring physician. In this pictorial review, we show the clinical significance of different patterns of thyroid uptake on FDG-PET [PET/computed tomography (CT)], including ultrasonography (US) findings.

The Use of PET-CT in Rheumatology

Positron emission tomography (PET) is a sensitive imaging tool that gives quantitative measure of underlying inflammation. Computed tomography (CT) scan used in combination with PET further helps to delineate the anatomical structure. PET-CT can be helpful for the early diagnosis of rheumatic diseases by pattern recognition, but its role in disease monitoring still needs further evaluation. It is not a fast track solution for all because of different sensitivity and specificity to different diseases, relative high cost, and radiation exposure to the patients.

Performance of 18-fluoro-2-deoxyglucose positron emission tomography for esophageal cancer screening

AIM

To evaluate the performance of 18-fluoro-2-deoxyglucose positron emission tomography (FDG-PET) for esophageal cancer (EC) screening.

METHODS

We retrospectively analyzed the data of consecutive asymptomatic individuals who underwent FDG-PET and esophagogastroduodenoscopy (EGD) simultaneously for cancer screening at our institution from February 2004 to March 2013. In total, 14790 FDG-PET and EGD procedures performed for 8468 individuals were included in this study, and the performance of FDG-PET for EC screening was assessed by comparing the results of FDG-PET and EGD, considering the latter as the reference.

RESULTS

Thirty-two EC lesions were detected in 28 individuals (31 squamous cell carcinomas and 1 adenocarcinoma). The median tumor size was 12.5 mm, and the depths of the lesions were as follows: Tis (n = 12), T1a (n = 15), and T1b (n = 5). Among the 14790 FDG-PET procedures, 51 examinations (0.3%) showed positive findings in the esophagus; only 1 was a true-positive finding. The screen sensitivity, specificity, positive predictive value, and negative predictive value of FDG-PET for ECs were 3.6% (95%CI: 0.1-18.3), 99.7% (95%CI: 99.6-99.7), 2.0% (95%CI: 0.0-10.4), and 99.8% (95%CI: 99.7-99.9), respectively. Of the 50 FDG-PET false-positive cases, 31 were observed in the lower esophagus, and gastroesophageal reflux disease was observed in 17 of these 31 cases.

CONCLUSION

This study is the first to clarify the FDG-PET performance for EC screening. Based on the low screen sensitivity, FDG-PET is considered to be difficult to use as a screening modality for ECs.

Can positron emission tomography detect colorectal adenomas and cancers?

BACKGROUND AND AIM

Fluorine-18 2-fluoro-2-deoxy-d-glucose positron emission tomography (PET) is effective and less invasive than other modalities used to diagnose tumors, including colorectal cancer (CRC). However, the detectability of adenomas and CRCs, especially in the early stages, is unclear.

METHODS

We evaluated the records of 2323 consecutive eligible patients who underwent both a total colonoscopy (TCS) and PET between October 2002 and September 2012 at a tertiary cancer center. The PET findings were verified by TCS performed independently within 1 year. Target lesions were defined as CRCs and adenomas that were 6 mm or larger in size.

RESULTS

Total colonoscopy detected 532 target lesions ≥ 6 mm in size: 56 T2-T4 CRCs, 39 T1 CRCs, 223 advanced adenomas, and 214 low-grade adenomas. Of the 532 lesions, 216 (40.6%) were PET positive. Of the 369 cases with positive uptakes, PET detected target lesions in the matched segments for 58.5% (216/369). Sensitivity of PET to T2-T4 CRCs, T1 CRCs, advanced adenomas, and low-grade adenomas was 92.9%, 79.5%, 50.7%, and 9.3%, respectively. PET could detect 76.5% (13/17) of T1 CRCs whose size is 10 to 19 mm and 85.0% (17/20) of T1 CRCs equal or larger than 20 mm. The multivariate analysis excluding T2-T4 CRCs showed malignant histology, larger size, protruded lesions, villous histology, and lesions in distal colon were significant factors.

CONCLUSIONS

Sensitivity of PET for detecting T2-T4 and even T1 cancers are promising. However, sensitivity of PET to adenomas, even advanced adenomas, is limited.

Whole-Body 18F-FDG PET/CT Is Superior to CT as First-Line Diagnostic Imaging in Patients Referred with Serious Nonspecific Symptoms or Signs of Cancer: A Randomized Prospective Study of 200 Patients

A fast-track pathway has been established in Denmark to investigate patients with serious nonspecific symptoms and signs of cancer (NSSC), who are not eligible to enter an organ-specific cancer program. The prevalence of cancer in this cohort is approximately 20%. The optimal screening strategy in patients with NSSC remains unknown. The aim of the study was to investigate whether ¹⁸F-FDG PET/CT was superior to CT as an initial imaging modality in patients with NSSC. In a randomized prospective trial, the imaging modalities were compared with regard to diagnostic performance. Methods: Two hundred patients were randomized 1:1 to whole-body ¹⁸F-FDG PET/CT or CT of the thorax and abdomen as the imaging modality. A tentative diagnosis was established after first-line imaging. The final referral diagnosis was adjudicated by the physician, when sufficient data were available. Results: One hundred ninety-seven patients were available for analysis because 3 patients withdrew consent before scanning. Thirty-nine (20%) patients were diagnosed with cancer, 10 (5%) with an infection, 15 (8%) with an autoimmune disease, and 76 (39%) with other diseases. In the remaining 57 patients (28%), no specific disease was found. ¹⁸F-FDG PET/CT had a higher specificity (96% vs. 85%; P = 0.028) and a higher accuracy (94% vs. 82%; P = 0.017) than CT. However, there were no statistically significant differences in sensitivity (83% vs. 70%) or negative predictive values (96% vs. 92%). No difference in days to final referral diagnosis according to randomization group could be shown (7.2 vs. 7.6 d). However, for the subgroups in which the imaging modality showed a suggestion of malignancy, there was a significant delay to final diagnosis in the CT group compared with the ¹⁸F-FDG PET/CT group (11.6 vs. 5.7 d; P = 0.02). Conclusion: Compared with CT, we found a higher diagnostic specificity and accuracy of ¹⁸F-FDG PET/CT for detecting cancer in patients with NSSC. ¹⁸F-FDG PET/CT should therefore be considered as first-line imaging in this group of patients.

Sensitivity of 2-[18F]fluoro-2-deoxyglucose positron emission tomography for advanced colorectal neoplasms: a large-scale analysis of 7505 asymptomatic screening individuals

BACKGROUND

The sensitivity of 2-[¹⁸F]fluoro-2-deoxyglucose positron emission tomography (FDG-PET) for advanced colorectal neoplasms among healthy subjects is not yet fully understood. The present study aimed to clarify the sensitivity by analyzing large-scale data from an asymptomatic screening population.

METHODS

A total of 7505 asymptomatic screenees who underwent both FDG-PET and colonoscopy at our Cancer Screening Division between February 2004 and March 2013 were analyzed. FDG-PET and colonoscopy were performed on consecutive days, and each examination was interpreted in a blinded fashion. The results of the two examinations were compared for each of the divided six colonic segments, with those from colonoscopy being set as the reference. The relationships between the sensitivity of FDG-PET and clinicopathological features of advanced neoplasms were also evaluated.

RESULTS

Two hundred ninety-one advanced neoplasms, including 24 invasive cancers, were detected in 262 individuals. Thirteen advanced neoplasms (advanced adenomas) were excluded from the analysis because of the coexistence of lesions in the same colonic segment. The sensitivity, specificity, and positive and negative predictive values of FDG-PET for advanced neoplasms were 16.9 % [95 % confidence interval (CI) 12.7-21.8 %], 99.3 % (95 % CI 99.2-99.4 %), 13.5 % (95 % CI 10.1-17.6 %), and 99.4 % (95 % CI 99.3-99.5 %), respectively. The sensitivity was lower for lesions with less advanced histological grade, of smaller size, and flat-type morphology, and for those located in the proximal part of the colon.

CONCLUSIONS

FDG-PET is believed to be difficult to use as a primary screening tool in population-based colorectal cancer screening because of its low sensitivity for advanced neoplasms. Even when it is used in opportunistic cancer screening, the limit of its sensitivity should be considered.

Application of whole-body FDG-PET for cancer screening in a cohort of hospital employees

Whole-body positron emission tomography/computed tomography with the glucose analog 2-[F]fluoro-2-deoxy-D-glucose (FDG-PET/CT) has been extensively used to screen for underlying malignancies in asymptomatic individuals. We were able to survey a cohort of hospital employees using FDG-PET/CT and to report the results herein.A total of 116 hospital employees older than 55 years old were offered whole-body FDG-PET in our hospital. Ninety-seven employees (83.6%) completed the assessment from February 2014 to August 2014 in our PET center. The final confirmation of cancer was based on pathologic examination and follow-up after more than 1 year.Among the 97 participants, 92 were asymptomatic and 5 presented with previously diagnosed cancers. Six of the 92 asymptomatic participants (6.6%) with significant nodular lesions were referred for histological or cytological evaluation of the possibility of malignancy, and 1 case was considered clinically important and required surgical resection. The cancer discovery rate was 3.3% (3/92) with positive predictive value of 50% (3/6). In the 5 participants with previously identified cancers, no recurrence or metastasis was detected.The offer of whole-body FDG-PET for cancer screening was welcomed with enthusiasm by most of the hospital employees. PET/CT combines the merits of PET and CT and can be administered to and provide benefits to a select group of hospital employees.

Is There Use for FDG-PET in Prostate Cancer?

The use of positron emission tomography (PET) with ¹⁸F-fluorodeoxyglucose (FDG) in prostate cancer depends on the phase of the disease along the natural history of this prevalent malignancy in men. Incidental high FDG uptake in the prostate gland, although rare, should prompt further investigation with at least a measurement of serum prostate specific antigen level. Although in general FDG uptake level may significantly overlap among normal, benign, and malignant tissues, aggressive primary tumors with Gleason score > 7 tend to display high FDG uptake. PET with FDG may be useful in staging of those patients with aggressive primary tumors and can localize the site of disease in a small fraction of men with biochemical failure and negative conventional imaging studies. FDG-PET may be quite useful in treatment response assessment and prognostication of patients with castrate-resistant metastatic prostate cancer.

(11)C-methylaminoisobutyric acid (MeAIB) PET for evaluation of prostate cancer: compared with (18)F-fluorodeoxyglucose PET

OBJECTIVE

α-N-methyl-(11)C-methylaminoisobutyric acid ((11)C-MeAIB) is a selective substrate of system A amino acid transport, and known to accumulate in malignant lesions. The aim of this study was to evaluate the utility of MeAIB PET for the assessment of prostate cancer, compared with FDG PET.

METHODS

Thirty-four men (age range 57-77 years) with prostate cancer were prospectively enrolled, and underwent MeAIB PET and FDG PET between January 2011 and January 2013. MeAIB PET and FDG PET were performed at 20 and 50 min post-injection, respectively. SUVmax of the prostate was calculated, and visual analysis was conducted for MeAIB and FDG PET studies. MRI images were visually evaluated if available. All patients received total prostatectomy subsequently, and imaging findings were compared with pathological results, including T stage, Gleason score, and tumor size. The patient-based and lesion-based sensitivity and specificity were calculated according to pathological significant cancer.

RESULTS

Mean value of SUVmax of (11)C-MeAIB PET and (18)F-FDG PET in prostate cancer were 3.18 (±1.90, range; 1.55-9.57) and 3.88 (±2.85, range; 2.04-14.47). MeAIB PET and FDG PET were positive by visual analysis in 47.1 % (16/34) and 44.1 % (15/34) of the patients. MRI was positive in 51.5 % (17/33). Pathological stage and Gleason score were as follows: Stage 2 (n = 23), 3 (n = 8), and 4 (n = 3); Gleason score 6 (n = 13), 7 (n = 16), 8 (n = 3), and 9 (n = 2). The sensitivities tended to be higher according to higher pathological T stage or Gleason sum score for both MeAIB and FDG PET studies. Visual analysis of both MeAIB PET and FDG PET had significant correlation with extraprostatic extension (p < 0.05). MeAIB PET and FDG PET had complementary results by visual analysis in the assessment of prostate cancer. The patient-based sensitivity of MeAIB PET, FDG PET, and MRI were 51.6, 48.4, and 56.7 %, respectively. The patient-based specificity of these modalities was 100 % for each modality.

CONCLUSIONS

MeAIB PET has better diagnostic results than FDG PET for the assessment of significant prostate cancer, and these PET studies showed complementary results. MRI has even better diagnostic results than (11)C-MeAIB PET. MeAIB accumulates in prostate cancer, which indicates that the system A amino acid transport pathway is activated in prostate cancer.

FDG PET/CT allowing detection and follow-up of tumor cell transplantation

After detection of small cell lung cancer in a 67-year-old patient who had donated a kidney 7 months earlier, the graft recipient underwent FDG-PET/CT to determine the presence/absence of tumor cell transmission. It showed abnormal increased uptake of the renal graft, associated with hypermetabolic lymph nodes and hepatic, pulmonary and bone lesions. Emergency graft resection was performed 5 days after PET/CT, permitting immunosuppressive therapy withdrawal. Pathologic examination of the kidney showed parenchymal infiltration by tumor cells compatible with small cell lung cancer. Thereafter, pathologists proved that the recipient's and donor's tumor cells matched using microsatellite markers. FDG-PET/CT was performed in the follow-up and showed progression in the donor despite chemotherapy and radiotherapy. He died a few months later. However, FDG-PET/CT showed a complete metabolic response after only 3 courses of chemotherapy in the recipient.

18F-fluorodeoxyglucose PET/CT for detection of disease in patients with prostate-specific antigen relapse following radical treatment of a local-stage prostate cancer

The present study aimed to retrospectively review the contribution of ¹⁸F-fluorodeoxygluose-positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) in the assessment of biochemical recurrence in patients with a diagnosis of local-stage prostate cancer (PCa) who underwent radical prostatectomy (RP) or received external beam radiation therapy (EBRT). A total of 28 patients who underwent RP or received EBRT for PCa between July 2007 and April 2013, and who underwent ¹⁸F-FDG PET/CT scanning for re-staging due to biochemical recurrence were included in the present study. The mean age of the patients was 65.07 years and the standard deviation was 7.51 years (range, 51-82 years). Of the 28 patients, 23 (82.1%) underwent RP and 5 (17.9%) received definitive EBRT. Prior to scanning, all patients were required to fast for 6 h, and ~1 h after the intravenous injection of 555 MBq ¹⁸F-FDG, whole-body PET scans were performed from the skull base to the upper thighs. Whole-body CT scans were performed in the craniocaudal direction. ¹⁸F-FDG PET images were reconstructed using CT data for attenuation correction. Histopathology examination or clinical follow-up was used to confirm any suspicious recurrent or metastatic lesions. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of ¹⁸F-FDG PET/CT were 61.6, 75.0, 61.6, 75.0 and 71.4%, respectively. ¹⁸F-FDG PET/CT can detect local and distant metastases with a high accuracy in the assessment of biochemical recurrence, thus detecting occult metastases and allowing the re-staging of PCa in the patients receiving definitive treatment. It is considered that ¹⁸F-FDG PET/CT may be useful in re-assessing the patients with PCa receiving definitive treatment.

Prognostic value and clinical correlations of 18-fluorodeoxyglucose metabolism quantifiers in gastric cancer

AIM: To investigate the correlations of pre-treatment positron emission tomography-computer tomography (PET-CT) metabolic quantifiers with clinical data of unstratified gastric cancer (GC) patients.

METHODS: Forty PET-CT scans utilising 18-fluorodeoxyglucose in patients who received no prior treatment were analysed. Analysis involved measurements of maximum and mean standardised uptake volumes (SUV), coefficient of variation (COV), metabolic tumour volumes and total lesion glycolysis of different thresholds above which the tumor volumes were identified. The threshold values were: SUV absolute value of 2.5, 30% of SUVmax, 40% of SUVmax, and liver uptake-based (marked _2.5, ₃₀, ₄₀ and _liv, respectively). Clinical variables such as age, sex, clinical stage, performance index, weight loss, tumor histological type and grade, and CEA and CA19.9 levels were included in survival analysis. Patients received various treatment modalities appropriate to their disease stage and the outcome was defined by time to metastasis (TTM) and overall survival (OS). Clinical and metabolic parameters were evaluated by analysis of variance, receiver operating characteristics, univariate Kaplan-Meier, and multivariate Cox models. P < 0.05 was considered statistically significant.

RESULTS: Significant differences were observed between initially disseminated and non-disseminated patients in mean SUV (6.05 vs 4.13, P = 0.008), TLG_2.5 (802 cm³vs 226 cm³; P = 0.031), and TLG₃₀ (436 cm³vs 247 cm³, P = 0.018). Higher COV was associated with poor tumour differentiation (0.47 for G3 vs 0.28 for G1 and G2; P = 0.03). MTV_2.5 was positively correlated to patient weight loss (< 5%, 5%-10% and > 10%: 40.4 cm³vs 123.6 cm³vs 181.8 cm³, respectively, P = 0.003). In multivariate Cox analysis, TLG₃₀ was prognostic for OS (HR = 1.001, 95%CI: 1.0009-1.0017; P = 0.047) for the whole group of patients. In the same model yet only including patients without initial disease dissemination TLG₃₀ (HR = 1.009, 95%CI: 1.003-1.014; P = 0.004) and MTV_2.5 (HR = 1.02, 95%CI: 1.002-1.036; P = 0.025) were prognostic for OS; for TTM TLG₃₀ was the only significant prognostic variable (HR = 1.006, 95%CI: 1.001-1.012; P = 0.02).

CONCLUSION: PET-CT in GC may represent a valuable diagnostic and prognostic tool that requires further evaluation in highly standardised environments such as randomised clinical trials.

(18)F-FDG-PET/CT and (18)F-NaF-PET/CT in men with castrate-resistant prostate cancer

To evaluate (18)F-labeled-fluorodeoxyglucose ((18)F-FDG-) and (18)F-labeled-sodium fluoride ((18)F-NaF-) positron emission tomography/computed tomography (PET/CT) as biomarkers in metastatic castrate-resistant prostate cancer (mCRPC). Nine men (53-75 years) in a phase 1 trial of abiraterone and cabozantinib had (18)F-FDG-PET/CT, (18)F-NaF-PET/CT and standard imaging ((99m)Tc-labeled-methylene-diphosphonate ((99m)Tc-MDP) bone scan and abdominal/pelvic CT) at baseline and after 8 weeks of therapy. Baseline disease was classified as widespread (18)F-FDG-avid, oligometastatic (18)F-FDG-avid (1 site), or non-(18)F-FDG-avid. Metabolic response was classified using European Organisation for Research and Treatment of Cancer (EORTC) criteria. Treatment response using Response Evaluation Criteria in Solid Tumors (RECIST) 1.1, Prostate Cancer Working Group 2 (PCWG2) guidelines and days on trial (DOT) were recorded. All men were followed for 1 year or until progression. Four men had (18)F-FDG-avid disease: two with widespread (DOT 53 and 76) and two with oligometastatic disease (DOT 231 and still on trial after 742+ days). Five men had non-(18)F-FDG-avid disease; three remained stable or improved (2 still on trial while one discontinued for non-oncologic reasons; DOT 225-563+), and 2 progressed (DOT 285 and 532). Despite the small sample size, Kaplan-Meier analysis showed a significant difference in progression free survival (PFS) between men with widespread (18)F-FDG-avid, oligometastatic (18)F-FDG-avid and non-(18)F-FDG-avid disease (p < 0.01). All men had (18)F-NaF-avid disease. Neither (18)F-NaF-avid disease extent nor intensity was predictive of treatment response. (18)F-FDG-PET/CT may be superior to (18)F-NaF-PET/CT and standard imaging in men with mCRPC on abiraterone and cabozantinib. (18)F-FDG-PET/CT may have potential to stratify men into 3 groups (widespread vs. oligometastatic (18)F-FDG-avid vs. non-(18)F-FDG-avid mCRPC) to tailor therapy. Further evaluation is warranted.

Ability of 18-fludeoxyglucose positron emission tomography/CT to detect incidental cancer

OBJECTIVE

To determine the prevalence and clinical features of pathologically proven incidental cancer (IC) detected by whole-body fluorine-18 fludeoxyglucose ((18)F-FDG) positron emission tomography (PET)/CT, as well as the incidence of false-positive and false-negative results.

METHODS

We retrospectively reviewed reports derived from (18)F-FDG PET/CT images of 3079 consecutive patients with known or suspected malignancies for 3 years. Discrete focal uptake indicating IC was identified from reports as well as pathological or clinical diagnoses, and the clinical courses were investigated. The false-positive result was defined as uptake indicating IC but not pathologically confirmed as malignant during follow-up. The false-negative result was defined as pathologically proven IC detected by another modality at initial clinical work-up or diagnosed during the follow-up period.

RESULTS

We found (18)F-FDG uptake indicating IC in 6.7% of all patients, and IC was pathologically proven in 2.2% of all patients. The most common sites were the colon, lung and stomach. The median survival duration of patients with IC was 42 months. The results were false positive in 4.5% of all patients, and the results were false negative in 2.3% of all patients.

CONCLUSION

(18)F-FDG PET/CT is a valuable tool for detecting IC. The rates of false-positive and false-negative results are within acceptable range.

ADVANCES IN KNOWLEDGE

This is the first report to describe the survival of patients with IC, and the detailed features of false-negative results at actual clinical settings.

FDG in Urologic Malignancies

Kidney, bladder, and prostate cancer account for more than one-eighth of new cancer cases worldwide. Imaging in kidney cancer is dominated by computed tomography (CT). Positron emission tomography (PET) imaging of bladder cancer is hampered by the urinary excretion of the most common PET tracer, 18F-fluoro-deoxy-glucose (FDG). PET imaging has been applied more often in prostate cancer. FDG-PET/CT is claimed to have a high frequency of false-negative results in urologic cancers; however, this finding may instead reflect correctly the state of disease being due to slow-growing cancers with a good prognosis and without a need of therapy.

Imaging in prostate carcinoma

Imaging plays a central role in the detection, diagnosis, staging, and follow-up of prostate carcinoma. This article discusses the role of multiple imaging modalities in the diagnosis and staging of prostate cancer, with attention to imaging features of localized and metastatic disease, imaging adjuncts to improve prostate biopsy, and potential imaging biomarkers. In addition, the role of imaging in the management of prostate cancer, with emphasis on surveillance, evaluation of response to new therapies, and detection of recurrent disease is described. Lastly, future directions in prostate cancer imaging are presented.

Detection of prostate cancer by an FDG-PET cancer screening program: results from a Japanese nationwide survey

OBJECTIVES

The aim of this study was to analyze detection rates and effectiveness of (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) cancer screening program for prostate cancer in Japan, which is defined as a cancer-screening program for subjects without known cancer. It contains FDG-PET aimed at detection of cancer at an early stage with or without additional screening tests such as prostate-specific antigen (PSA) and magnetic resonance imaging (MRI).

METHODS

A total of 92,255 asymptomatic men underwent the FDG-PET cancer screening program. Of these, 504 cases with findings of possible prostate cancer in any screening method were analyzed.

RESULTS

Of the 504 cases, 165 were verified as having prostate cancer. Of these, only 61 cases were detected by FDG-PET, which result in 37.0% relative sensitivity and 32.8% positive predictive value (PPV). The sensitivity of PET/computed tomography (CT) scanner was higher than that of dedicated PET (44.0% vs. 20.4%). However, the sensitivity of FDG-PET was lower than that of PSA and pelvic MRI. FDG-PET did not contribute to improving the sensitivity and PPV when performed as combined screening.

CONCLUSION

PSA should be included in FDG-PET cancer screening programs to screen for prostate cancer.

Detection of colorectal cancer and adenomas by FDG-PET cancer screening program: results based on a nationwide Japanese survey

PURPOSE

The aim of this study was to analyze the detection rate for CRC and adenomas for asymptomatic subjects in Japan by FDG-PET cancer screening program carried out between 2006 and 2009.

METHODS

The "FDG-PET cancer screening program" included both PET and positron emission tomography with computed tomography (PET/CT) with or without other screening tests. A total of 154,783 asymptomatic subjects underwent FDG-PET cancer screening program; we analyzed the 1,808 cases with findings from any detection method that indicated suspected CRC.

RESULTS

Among the 1,808 cases, the number of cases verified as CRC and adenoma was 394 and 679, respectively. The sensitivity and positive predictive value (PPV) of FDG-PET were 86.0 and 31.7% for CRC, and 63.6 and 63.8% for CRC and adenoma. The sensitivity and PPV of fecal occult blood test (FOBT) for CRC were lower than those of FDG-PET, but higher for adenoma. Therefore, FDG-PET and FOBT were complementary for screening for CRC, and CRC and adenoma. The majority of CRC detected by the FDG-PET imaging was UICC stage 0 or I, however, detection of smaller or less invasive cancer was limited.

CONCLUSION

The FDG-PET screening program in Japan has detected CRC at an early stage and adenomas as premalignant lesions. A combination of FDG-PET and FOBT yields the best results if the intent is to detect either CRC or adenoma. However, it is absolutely clear that an FDG-PET cancer screening program cannot detect all colon lesions.

Fluorodeoxyglucose positron emission tomography may aid the diagnosis of aggressive primary prostate cancer: A case series study

Recent evidence has shown that positive results may be observed for fluorodeoxyglucose-positron emission tomography (FDG-PET) in undifferentiated, biologically aggressive and metastatic tumors. The present study describes a case series of six patients with normal prostate-specific antigen (PSA) serum levels who underwent FDG-PET due to other causes. Positive PET results were observed at the prostate and the patients were subsequently diagnosed with high-risk prostate cancer. Clinical, anamnestic, laboratory and instrumental data were collected from six asymptomatic patients with total serum PSA levels of <4 ng/ml who had undergone FDG-PET due to other causes. The FDG-PET and prostate biopsy were positive for prostate cancer. All the patients were treated with radical intent. The median age was 66 years (range, 52-72 years), the median total PSA value was 2.4 ng/ml (range, 1.5-3.9 ng/ml) and the body mass index was 26.4 (range, 21.8-30.2). Three of the six patients underwent FDG-PET due to a clinical suspicion of multiple myeloma, while three patients were examined for other oncological diseases. The pathological analysis at the prostate biopsy revealed three patients with a Gleason score of 6, two with a score of 7 (4+3) and one with a score of 8 (4+4). Five of the six patients were treated by radical prostatectomy and one by radiotherapy. The pathological analysis revealed one patient of pT2a stage, three of pT2c and one of pT3b. No patients demonstrated lymph node invasion. The definitive Gleason score was 3+3 in one patient, 4+3 in one patient, 4+4 in two patients and 5+3 in one patient. Following a median follow-up time of six months (range, 1-12 months), five of the six patients underwent FDG-PET again, which revealed negative results. At the end of this study, these patients were alive without evidence of disease. By contrast, one patient demonstrated positive FDG-PET results. In conclusion, FDG-PET has been used to characterize prostate cancers in patients with apparently normal PSA levels.

Positron emission mammography (PEM): reviewing standardized semiquantitative method

Purpose

To validate semiquantitative analysis of positron emission mammography (PEM).

Methods

Fifty women with histologically confirmed breast lesions were retrospectively enrolled. Semiquantitative uptake values (4 methods), the maximum PEM uptake value (PUVmax), and the lesion-to-background (LTB) value (3 methods) were measured. LTB is a ratio of the lesion’s PUVmax to the mean background; LTB1, LTB2, and LTB3 (which were calculated on different background) were used to designate the three values measured. Interobserver reliability between two readers for PUVmax and the LTBs was tested using the interobserver correlation coefficient (ICC). The likelihood ratio test was used to evaluate the relationship between ICCs. Receiver operating characteristic (ROC) curves were calculated for all methods. Diagnostic accuracy in differentiating benign tissue from malignant tissue was compared between PUVmax and LTB1.

Results

The ICC rate was 0.971 [95 % confidence interval (CI) 0.943–0.986] for PUVmax, 0.873 (95 % CI 0.758–0.935) for LTB1, 0.965 (95 % CI 0.925–0.983) for LTB2, and 0.895 (95 % CI 0.799–0.946) for LTB3. However, there were some technical difficulties in the practical use of LTB2 and LTB3. The likelihood ratio test between PUVmax and LTB1 was statistically significant (p < 0.001). ROC curves of the 4 methods had similar characteristics. The median PUVmax was 1.39 for benign lesions and 3.70 for malignant lesions. LTB1 was 1.92 for benign lesions and 4.78 for malignant lesions. Significant differences (p < 0.001) in both PUVmax and LTB1 were observed between groups.

Conclusion

Due to its simplicity and reproducibility, PUVmax is superior to LTB as an indicator for PEM in semiquantitative analysis.

Imaging evaluation of prostate cancer with 18F-fluorodeoxyglucose PET/CT: utility and limitations

Prostate cancer is a major public health problem in developed countries. The remarkable biological and clinical heterogeneity of prostate cancer provides unique opportunities as well as challenges for the diagnostic imaging evaluation of this prevalent disease. The disease is characterized by a natural history that ranges from localized slowly growing hormone-dependent tumor progressing to metastatic hormone-refractory disease. PET is an ideal imaging tool for noninvasive interrogation of the underlying tumor biology. (18)F-FDG is the most common PET radiotracer used for oncological applications based upon elevated glucose metabolism in malignant tissue in comparison to normal tissue. FDG uptake in prostate cancer depends on tumor differentiation with low accumulation in well-differentiated tumors and high uptake in aggressive poorly differentiated tumors. Cumulative current evidence suggests that FDG PET may be useful in detection of disease in a small fraction of patients with biochemical recurrence, in the imaging evaluation of extent and treatment response in metastatic disease and in prediction of patient outcome.