Clinical Indications and Impact on Management: Fourth and Subsequent Posttherapy Follow-up 18F-FDG PET/CT Scans in Oncology Patients

Clinical practice consensus for the diagnosis and management of melanoma in Taiwan

Melanoma is rare in Taiwan. Asian melanoma is distinct from Western melanoma because acral and mucosal melanoma accounts for the majority of melanoma cases, leading to distinct tumor behaviors and genetic profiling. With consideration of the clinical guidelines in Western countries, Taiwanese experts developed a local clinical practice consensus guideline. This consensus includes diagnosis, staging, and surgical and systemic treatment, based only on clinical evidence, local epidemiology, and available resources evaluated by experts in Taiwan. This consensus emphasizes the importance of surgical management, particularly for sentinel lymph node biopsies. In addition, molecular testing for BRAF is mandatory for patients before systemic treatment. Furthermore, immunotherapy and targeted therapy are prioritized for systemic treatment. This consensus aimed to assist clinicians in Taiwan in diagnosing and treating patients according to available evidence.

Characterizing and quantifying low-value diagnostic imaging internationally: a scoping review

BACKGROUND

Inappropriate and wasteful use of health care resources is a common problem, constituting 10-34% of health services spending in the western world. Even though diagnostic imaging is vital for identifying correct diagnoses and administrating the right treatment, low-value imaging-in which the diagnostic test confers little to no clinical benefit-is common and contributes to inappropriate and wasteful use of health care resources. There is a lack of knowledge on the types and extent of low-value imaging. Accordingly, the objective of this study was to identify, characterize, and quantify the extent of low-value diagnostic imaging examinations for adults and children.

METHODS

A scoping review of the published literature was performed. Medline-Ovid, Embase-Ovid, Scopus, and Cochrane Library were searched for studies published from 2010 to September 2020. The search strategy was built from medical subject headings (Mesh) for Diagnostic imaging/Radiology OR Health service misuse/Medical overuse OR Procedures and Techniques Utilization/Facilities and Services Utilization. Articles in English, German, Dutch, Swedish, Danish, or Norwegian were included.

RESULTS

A total of 39,986 records were identified and, of these, 370 studies were included in the final synthesis. Eighty-four low-value imaging examinations were identified. Imaging of atraumatic pain, routine imaging in minor head injury, trauma, thrombosis, urolithiasis, after thoracic interventions, fracture follow-up and cancer staging/follow-up were the most frequently identified low-value imaging examinations. The proportion of low-value imaging varied between 2 and 100% inappropriate or unnecessary examinations.

CONCLUSIONS

A comprehensive list of identified low-value radiological examinations for both adults and children are presented. Future research should focus on reasons for low-value imaging utilization and interventions to reduce the use of low-value imaging internationally.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO: CRD42020208072.

Clinical and Prognostic Value of 18F-FDG-PET/CT in the Restaging Process of Recurrent Cutaneous Melanoma

BACKGROUND

Several studies on 18F-FDG-PET/CT have investigated the prognostic role of this imaging modality in different tumors after treatment. Nevertheless, its role in restaging patients with recurrent CM still needs to be defined.

OBJECTIVE

The aim of this retrospective multicenter study was to evaluate the clinical and prognostic impact of 18F-FDG-PET/CT on the restaging process of cutaneous melanoma (CM) after surgery in patients with suspected distant recurrent disease or suspected metastatic progression disease.

MATERIALS AND METHODS

74 patients surgically treated for CM underwent 18F-FDG-PET/CT for suspected distant recurrent disease or suspected metastatic progression disease. The diagnostic accuracy of visually interpreted 18F-FDG-PET/CT was obtained by considering histology (n=21 patients), other diagnostic imaging modalities performed within 2 months of PET/CT (CT in 52/74 patients and Whole-Body MRI in 18/74 patients) and clinical follow-up (n=74 patients) for at least 24 months containing all the clinical and diagnostic information useful for the PET performance assessment and outcome. Progression-free survival (PFS) and overall survival (OS) were assessed by using the Kaplan- Meier method. The risk of progression (Hazard Ratio-HR) was computed by the Cox regression analysis.

RESULTS

Suspicion of recurrent CM was confirmed in 24/27 patients with a positive 18F-FDG-PET/CT scan. Overall, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy of 18F-FDG-PET/CT were 82%, 93%, 88%, 89%, and 89%, respectively, with area under the curve being 0.87 (95%IC 0.78-0.97; p<0.05). 18F-FDG-PET/CT findings significantly influenced the therapeutic management in 18 patients (modifying therapy in 10 patients; guiding surgery in 8 patients). After 2 years of follow-up, PFS was significantly longer in patients with a negative vs. a positive 18F-FDG-PET/CT scan (90% vs 46%, p<0.05; Fig. 1). Moreover, a negative scan was associated with a significantly longer OS than a positive one (76% vs 39% after 2 years, p<0.05; Fig. 2). In addition, a positive 18F-FDG-PET/CT scan was associated with an increased risk of disease progression (HR=8.2; p<0,05).

CONCLUSION

18F-FDG-PET/CT showed a valuable diagnostic performance in patients with suspicion of recurrent CM. This imaging modality might have an important prognostic value in predicting the survival outcomes, assessing the risk of disease progression, and guiding treatment decision making.

Recurrence of Melanoma After Initial Treatment: Diagnostic Performance of FDG PET in Posttreatment Surveillance

Purpose

In malignant melanoma, recurrence is often observed in distant areas from the primary site. While FDG PET is a sensitive imaging for detecting malignant lesions, the role of FDG PET in posttreatment surveillance period has not been investigated sufficiently. The aim of this study was to evaluate the value of PET during posttreatment surveillance in melanoma.

Methods

A total of 76 melanoma patients who underwent FDG PET during surveillance period after completion of the first treatment were retrospectively enrolled. PET scans were grouped according to the purpose and clinical situations, routine surveillance, or evaluating clinical suspicion. Final diagnosis of recurrence was determined by complete clinical evaluation or long-term follow-up. In each situation, the diagnostic role of FDG PET was assessed.

Results

A total of 143 scans of 76 patients were analyzed: 51 for clinical suspicion and 92 for routine surveillance. In the clinical suspicion group, PET correctly diagnosed non-recurrence in 10 cases (20%). In routine surveillance group, 16 cases (17%) presented recurrence, all of which was correctly diagnosed on PET. NPV and PPV were 100% and 76%, respectively. In subgroup analysis, sensitivity and NPV were higher in the low-risk group (stages I-II_A) than in the high-risk group (stages II_B-IV), while specificity and PPV were higher in the high-risk group.

Conclusion

In conclusion, FDG PET is an effective diagnostic tool in posttreatment surveillance of melanoma. Even in cases without clinical suspicion, melanoma recurs in a considerable proportion of patients, which can be sensitively diagnosed on PET.

18-Fluoride labeled sodium fluoride positron emission tomography with computer tomography: the impact of pretreatment staging in intermediate- and high-risk prostate cancer

Background

18-Fluoride labeled sodium fluoride (Na-18-F) positron emission tomography with computer tomography (PET/CT) has a better sensitivity and specificity than whole body bone scan (WBBS) in detecting osseous metastatic prostate cancer. We performed a pilot study of 20 men to examine what level of impact Na-18-F PET/CT has on management plans when used for staging newly diagnosed prostate cancer.

Materials and methods

Twenty men were prospectively enrolled into the study in South Australia. Men were eligible if they had newly diagnosed, untreated, and biopsy-confirmed intermediate- or high-risk prostate cancer (D'Amico classification). WBBS and Na-18-F PET/CT scans were performed within 1 week of each other. Following review of the WBBS, treatment type and intent was documented by the treating urologist. The Na-18-F PET/CT scan was then reviewed. The impact of the Na-18-F PET/CT was measured on whether treatment modality or intent was subsequently altered: high impact = treatment intent or modality was changed; medium impact = treatment modality was modified; low impact = no change in treatment.

Results

In 18 men (90%), the WBBS and Na-18-F PET/CT were negative for osseous metastases. In one man (5%), the WBBS demonstrated widespread osseous metastases which were similarly demonstrated on the Na-18-F PET/CT. One man (5%) had a normal WBBS; however, the Na-18-F PET/CT demonstrated widespread osseous metastases. Subsequently, in 19 men (95%), the results of the two scans were congruent and the addition of the Na-18-F PET/CT scan demonstrated a low impact on management. In one man (5%), the addition of the Na-18-F PET/CT had a high impact as treatment type and intent was altered.

Conclusions

Our pilot study is the first of its kind in Australia, and our findings suggest that Na-18-F PET/CT is a safe and feasible modality for staging prostate cancer. However, its true impact on prostate cancer management warrants further investigation.

Incidence of Brain Metastases on Follow-up 18F-FDG PET/CT Scans of Non-Small Cell Lung Cancer Patients: Should We Include the Brain?

The brain is the most common site of distant metastasis from lung cancer. Thus, MRI of the brain at initial staging is routinely performed, but if this examination is negative a follow-up examination is often not performed. This study evaluates the incidence of asymptomatic brain metastases in non-small cell lung cancer patients detected on follow-up ¹⁸F-FDG PET/CT scans. Methods: In this Institutional Review Board-approved retrospective review, all vertex to thigh ¹⁸F-FDG PET/CT scans in patients with all subtypes of lung cancer from August 2014 to August 2016 were reviewed. A total of 1,175 ¹⁸F-FDG PET/CT examinations in 363 patients were reviewed. Exclusion criteria included brain metastases on initial staging, histologic subtype of small-cell lung cancer, and no follow-up ¹⁸F-FDG PET/CT examinations. After our exclusion criteria were applied, a total of 809 follow-up ¹⁸F-FDG PET/CT scans in 227 patients were included in the final analysis. The original report of each ¹⁸F-FDG PET/CT study was reviewed for the finding of brain metastasis. The finding of a new brain metastasis prompted a brain MRI, which was reviewed to determine the accuracy of the ¹⁸F-FDG PET/CT. Results: Five of 227 patients with 809 follow-up ¹⁸F-FDG PET/CT scans reviewed were found to have incidental brain metastases. The mean age of the patients with incidental brain metastasis was 68 y (range, 60-77 y). The mean time from initial diagnosis to time of detection of incidental brain metastasis was 36 mo (range, 15-66 mo). When MRI was used as the gold standard, our false-positive rate was zero. Conclusion: By including the entire head during follow-up ¹⁸F-FDG PET/CT scans of patients with non-small cell lung cancer, brain metastases can be detected earlier while still asymptomatic. But, given the additional scan time, radiation, and low incidence of new brain metastases in asymptomatic patients, the cost-to-benefit ratio should be weighed by each institution.