Economic evaluation of PET and PET/CT in oncology: evidence and methodologic approaches

A Systematic Literature Review of Modelling Approaches to Evaluate the Cost Effectiveness of PET/CT for Therapy Response Monitoring in Oncology

BACKGROUND AND OBJECTIVE

This systematic literature review addresses model-based cost-effectiveness studies for therapy response monitoring with positron emission tomography (PET) generally combined with low-dose computed tomography (CT) for various cancer types. Given the known heterogeneity in therapy response events, studies should consider patient-level modelling rather than cohort-based modelling because of its flexibility in handling these events and the time to events. This review aims to identify the modelling methods used and includes a systematic assessment of the assumptions made in the current literature.

METHODS

This study was conducted and reported following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 statement. Information sources included electronic bibliographic databases, reference lists of review articles and contact with experts in the fields of nuclear medicine, health technology assessment and health economics. Eligibility criteria included peer-reviewed scientific publications and published grey literature. Literature searches, screening and critical appraisal were conducted by two reviewers independently. The Consolidated Health Economic Evaluation Reporting Standards (CHEERS) were used to assess the methodological quality. The Bias in Economic Evaluation (ECOBIAS) checklist was used to determine the risk of bias in the included publications.

RESULTS

The search results included 2959 publications. The number of publications included for data extraction and synthesis was ten, representing eight unique studies. These studies addressed patients with lymphoma, advanced head and neck cancers, brain tumours, non-small cell lung cancer and cervical cancer. All studies addressed response to chemotherapy. No study evaluated response to immunotherapy. Most studies positioned PET/CT as an add-on modality and one study positioned PET/CT as a replacement for conventional imaging (X-ray and contrast-enhanced CT). Three studies reported decision-tree structures, four studies reported cohort-level state-transition models and one study reported a partitioned survival model. No patient-level models were reported. The simulation horizons adopted ranged from 1 year to lifetime. Most studies reported a probabilistic analysis, whereas two studies reported a deterministic analysis only. Two studies conducted a value of information analysis. Multiple studies did not adequately discuss model-specific aspects of bias. Most importantly and regularly observed were a high risk of structural assumptions bias, limited simulation horizon bias and wrong model bias.

CONCLUSIONS

Model-based cost-effectiveness analysis for therapy response monitoring with PET/CT was based on cohorts of patients instead of individual patients in the current literature. Therefore, the heterogeneity in therapy response events was commonly not addressed appropriately. Further research should include more advanced and patient-level modelling approaches to accurately represent the complex context of clinical practice and, therefore, to be meaningful to support decision making.

REGISTRATION

This review is registered in PROSPERO, the international prospective register of systematic reviews funded by the National Institute for Health Research, with CRD42023402581.

Prognostic value of pre-treatment 18F-FDG PET uptake for nasopharyngeal carcinoma

PURPOSE

To evaluate the prognostic value of maximal standardized uptake values (SUVmax) from serial fluor-18-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) in patients with nasopharyngeal carcinoma (NPC).

MATERIALS AND METHODS

Fifty-two patients with NPC who underwent 18F-FDG PET/CT scan before radiotherapy with/without chemotherapy were reviewed retrospectively. Twenty-seven patients (52%) were applied 3-D conformal radiotherapy and 25 patients (48%) applied intensity-modulated radiotherapy (IMRT). Fourteen (27%) patients were given neoadjuvant chemotherapy and forty-four (84.6%) patients were given concomitant and adjuvant chemotherapy.

RESULTS

Median follow-up time was 34 months (range 5.6-66.4 months). Forty-four (84.6%) patients were alive at last follow-up and eight (15.4%) had died. The best cut-off value of the SUVmax for the primary tumor site (SUVmax-PT) was 13 and 9 for the lymph nodes (SUVmax-LN). Patients with SUVmax-PT ≥ 13.0 and SUVmax-LN ≥ 9 had a significantly higher risk for the development of the distant metastases (p = 0.044 and p = 0.038). DFS was affected in patients with SUVmax-PT ≥ 13 (log rank χ 2 = 2.54, p = 0.017) and was significantly lower in patients with SUVmax-LN ≥ 9 for the lymph nodes (log rank χ 2 = 5.81, p = 0.013). OS was not affected by SUV levels. A multivariate Cox proportional hazard model of DFS included age (≥ 40), SUVmax-LN (< 9), T stage (T1-2) and neoadjuvant chemotherapy are significantly better prognosis for the DFS.

CONCLUSION

18F-FDG PET/CT uptake before treatment, as determined by SUVmax, may be a valuable tool to evaluate prognosis in NPC patients.

Role of molecular imaging in prognosis, diagnosis, and treatment of gastrointestinal cancers: An update on new therapeutic methods

One of the leading causes of cancer-related death is gastrointestinal cancer, which has a significant morbidity and mortality rate. Although preoperative risk assessment is essential for directing patient care, its biological behavior cannot be accurately predicted by conventional imaging investigations. Potential pathophysiological information in anatomical imaging that cannot be visually identified can now be converted into high-dimensional quantitative image features thanks to the developing discipline of molecular imaging. In order to enable molecular tissue profile in vivo, molecular imaging has most recently been utilized to phenotype the expression of single receptors and targets of biological therapy. It is expected that molecular imaging will become increasingly important in the near future, driven by the expanding range of biological therapies for cancer. With this live molecular fingerprinting, molecular imaging can be utilized to drive expression-tailored customized therapy. The technical aspects of molecular imaging are first briefly discussed in this review, followed by an examination of the most recent research on the diagnosis, prognosis, and potential future clinical methods of molecular imaging for GI tract malignancies.

[18F]FDG PET/CT versus [18F]FDG PET/MRI in the diagnosis of lymph node metastasis in nasopharyngeal carcinoma: a systematic review and meta-analysis

Purpose

This meta-analysis aimed to evaluate the comparative diagnostic accuracy of [18F]FDG PET/CT versus [18F]FDG PET/MRI in identifying lymph node metastases in individuals with nasopharyngeal carcinoma.

Methods

A comprehensive search was executed across PubMed, Embase, and Web of Science through September 2023 to identify studies evaluating the diagnostic precision of [18F]FDG PET/CT and [18F]FDG PET/MRI in detecting lymph node metastasis in nasopharyngeal carcinoma. Sensitivity and specificity were assessed through the DerSimonian-Laird method, incorporating the Freeman-Tukey transformation.

Results

The meta-analysis encompassed nine articles, involving a total of 916 patients. The overall sensitivity and specificity of [18F]FDG PET were 0.95 (95%CI: 0.88-1.00) and 0.95 (95%CI: 0.84-1.00). The overall sensitivity of [18F]FDG PET/CT was 0.94 (95%CI, 0.85-0.99), whereas [18F]FDG PET/MRI achieved a sensitivity of 1.00 (95%CI, 0.94-1.00). The findings reveal that [18F]FDG PET/CT demonstrates comparable sensitivity to [18F]FDG PET/MRI (p = 0.20). The overall specificity of [18F]FDG PET/CT was 0.94 (95%CI, 0.82-1.00), whereas [18F]FDG PET/MRI exhibited a specificity of 0.98 (95%CI, 0.93-1.00). Additionally, the results suggest that [18F]FDG PET/CT offers similar specificity to [18F]FDG PET/MRI (p = 0.11).

Conclusion

[18F]FDG PET demonstrates high sensitivity and specificity in identifying lymph node metastasis in nasopharyngeal carcinoma. Furthermore, [18F]FDG PET/CT exhibits comparable sensitivity and specificity to [18F]FDG PET/MRI.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=496006, PROSPERO (CRD42024496006).

PET/CT standardized uptake value and EGFR expression predicts treatment failure in nasopharyngeal carcinoma

OBJECTIVE

This study inventively combines epidermal growth factor receptor (EGFR) expression of the primary lesion and standardized uptake value (SUV) of positron emission tomography and computed tomography (PET/CT) to predict the prognosis of nasopharyngeal carcinoma (NPC). This study aimed to evaluate the predictive efficacy of maximum standard uptake value (SUVmax) and EGFR for treatment failure in patients with NPC.

METHODS

This retrospective study reviewed the results of EGFR expression and pretreatment ¹⁸F-FDG PET/CT of 313 patients with NPC. Time-dependent receiver operator characteristics was used for analyzing results and selecting the optimal cutoff values. Cox regression was used to screen out multiple risk factors. Cumulative survival rate was calculated by Kaplan-Meier.

RESULTS

The selected cutoff value of SUVmax-T was 8.5. The patients were categorized into four groups according to EGFR expression and SUVmax-T. There were significant differences in the 3-year local recurrence-free survival (LRFS) (p = 0.0083), locoregional relapse-free survival (LRRFS) (p = 0.0077), distant metastasis-free survival (DMFS) (p = 0.013), and progression-free survival (PFS) (p = 0.0018) among the four groups. Patients in the EGFR-positive and SUVmax-T > 8.5 group had the worst survival, while patients in the EGFR-negative and SUVmax-T ≤ 8.5 group had the best prognosis. Subsequently, patients with only positive EGFR expression or high SUVmax-T were classified as the middle-risk group. There were also a significant difference in 3-year overall survival among the three risk groups (p = 0.034). SUVmax-T was associated with regional recurrence-free survival and LRRFS in multivariate analysis, whereas EGFR was an independent prognostic factor for LRRFS, DMFS, and PFS.

CONCLUSION

The combination of SUVmax-T and EGFR expression can refine prognosis and indicate clinical therapy.

Selectively recommend 18F-FDG PET/CT for patients with de novo nasopharyngeal carcinoma in endemic areas

INTRODUCTION

To identify the subset of patients with de novo nasopharyngeal carcinoma (NPC) for whom [¹⁸F] fluorodeoxyglucose positron emission tomography and computed tomography (¹⁸F-FDG PET/CT) should be recommended, and to determine whether PET/CT is a cost-effective decision for precise M staging in endemic areas.

MATERIALS AND METHODS

Retrospective analysis of data of 4469 patients diagnosed with de novo NPC between January 2014 and December 2019. The detection rate of distant metastasis was compared between different groups. Univariate and multiple logistic regression analysis was applied to identify the risk factors for distant metastasis. The cost-effectiveness of the diagnostic strategies was assessed.

RESULTS

The detection rate of distant metastasis in the whole cohort was 5.46%. In multivariate analysis, male sex, T3-4 stage, N2-3 stage, and high plasma Epstein-Barr virus (EBV) DNA (≥ 14,650 copies/mL) were risk factors for distant metastases. NPC patients with T3-4 stage combined with N2-3 stage, high EBV DNA combined with male sex, or N2-3 stage combined with high EBV DNA were defined as recommended group with relatively higher tendency for metastasis. Distant metastasis incidence in recommended group and unrecommended group were 10.25% and 1.75%, respectively (P < 0.001). In the recommended group, PET/CT significantly improved the detection rate of distant metastasis (13.25% vs 9.02%, P = 0.005). Cost-effectiveness analysis revealed that additional cost for every one percent increase in distant metastasis detection rate was $22,785.58 in the recommended group (< Willingness-to-pay (WTP) threshold of $32,700.00) and $310,912.90 in the unrecommended group.

CONCLUSIONS

In patients with de novo NPC, the tendency for metastasis can be predicted based on clinical parameters. ¹⁸F-FDG PET/CT should be selectively recommended for the subset of patients with a relatively higher tendency for metastasis.

The Future of Nuclear Medicine as an Independent Specialty

In this article, we provide an overview of established and emerging conventional nuclear medicine and PET imaging biomarkers, as the diagnostic nuclear medicine portfolio is rapidly expanding. Next, we review briefly nuclear theranostic approaches that have already entered or are about to enter clinical routine. Using some approximations and taking into account emerging applications, we also provide some simplified business forecasts for nuclear theranostics. We argue that an optimistic outlook by the nuclear medicine community is crucial to the growth of the specialty and emphasize the urgent need for training adaptations.

A catalytic fluoride-rebound mechanism for C(sp3)-CF3 bond formation

The biological properties of trifluoromethyl compounds have led to their ubiquity in pharmaceuticals, yet their chemical properties have made their preparation a substantial challenge, necessitating innovative chemical solutions. We report the serendipitous discovery of a borane-catalyzed formal C(sp³)-CF₃ reductive elimination from Au(III) that accesses these compounds by a distinct mechanism proceeding via fluoride abstraction, migratory insertion, and C-F reductive elimination to achieve a net C-C bond construction. The parent bis(trifluoromethyl)Au(III) complexes tolerate a surprising breadth of synthetic protocols, enabling the synthesis of complex organic derivatives without cleavage of the Au-C bond. This feature, combined with the "fluoride-rebound" mechanism, was translated into a protocol for the synthesis of ¹⁸F-radiolabeled aliphatic CF₃-containing compounds, enabling the preparation of potential tracers for use in positron emission tomography.

Report on the development and application of PET/CT in mainland China

PURPOSE

To examine the development and application of systems combining positron emission and x-ray-computed tomography systems (PET/CTs) in mainland China.

METHODS

Using a questionnaire, we surveyed Chinese medical institutions on a variety topics relating to their PET/CT systems and its use. The respondents had PET/CTs installed and in clinical use before 31 December 2015. We examined the clinical scenarios to which Chinese PET/CTs were applied by reviewing the related Chinese and international literature from the start of 1995 to the end of 2013; these papers were found by searching the Wanfang and PubMed databases, respectively. The data were then classified and analyzed statistically.

RESULTS

At the end of 2015, there were 240 PET/CTs and 101 medical cyclotrons in mainland China. The total number of PET studies performed in 2015 was 469,364. The main clinical applications of PET were found to be diagnostic fludeoxyglucose (¹⁸F-FDG) imaging and oncological imaging. A minority of PET/CT studies were performed using ¹¹C-choline and other imaging agents. The number of papers relating to clinical use of PET/CT in mainland China increased each year over the period of study, in both the Chinese and international literature. Despite this progress, important problems were also apparent, including unbalanced regional development and the limited quality of the research.

CONCLUSIONS

This study provides detailed information for understanding the development PET/CT technology in mainland China, along with its geographical distribution and clinical application. It may thus prove a useful reference for all those involved in planning the future of PET/CT in China.

The use of bisphosphonates in the management of bone involvement from solid tumours and haematological malignancies - a European survey

Bone metastases in patients with solid tumours (ST) and bone lesions in patients with haematological malignancies (HM) are common. Associated skeletal-related events (SREs) cause severe pain, reduced quality of life and place a burden on health care resources. Bone-targeted agents can reduce the risk of SREs. We evaluated the management of bone metastasis/lesions in five European countries (France, Germany, Italy, Spain and the UK) by an observational chart audit. In total, 881 physicians completed brief questionnaires on 17 193 patients during the observation period, and detailed questionnaires for a further 9303 individuals. Patient cases were weighted according to the probability of inclusion. Although a large proportion of patients with bone metastases/lesions were receiving bisphosphonates, many had their treatment stopped (ST, 19%; HM, 36%) or will never be treated (ST, 18%; HM, 13%). The results were generally similar across the countries, although German patients were more likely to have asymptomatic bone lesions detected during routine imaging. In conclusion, many patients who could benefit from bone-targeted agents do not receive bisphosphonates and many have their treatment stopped when they could benefit from continued treatment. Developing treatment guidelines, educating physicians and increasing the availability of new agents could benefit patients and reduce costs.

Prognostic value of pre-treatment 18F-FDG-PET uptake in small-cell lung cancer

PURPOSE

Small-cell lung cancer (SCLC) is an aggressive disease, despite an initially favorable response to treatment, and its prognosis is still poor. Multiple parameters have been studied as possible prognostic factors, but none of them are reliable enough to change the treatment approach. ¹⁸F-fluorodeoxyglucose-positron emission tomography (FDG-PET) is a novel imaging technique for staging of SCLC. The aim of this study was to evaluate the prognostic value of pre-treatment FDG-PET parameters on clinical outcome in limited stage (LS) SCLC patients treated with curative thoracic radiotherapy (RT) and chemotherapy.

METHODS

Clinical records of 46 LS-SCLC patients with pre-treatment FDG-PET imaging were retrospectively reviewed. Patients were treated with definitive RT for a total dose of 50-60 Gy and chemotherapy. The clinical endpoints were progression-free survival (PFS) and overall survival (OS).

RESULTS

The median age was 59 (range 30-82) years, and median follow-up time was 23.2 months (range 5-82.8 months). Median OS was 30.9 months for pre-treatment tumor maximum standardized uptake value (SUV_max) <9.3 and 20.6 months for SUV_max ≥9.3 (p = 0.027) and PFS was 55.6 months for SUV_max <9.3 and 38.6 months for SUV_max ≥9.3 (p = 0.16). Median OS was 73 months for pre-treatment lymph node SUV_max <5.8 and 21 months for ≥5.8 (p = 0.01) and PFS was 38.6 months (range 6.8-70.3 months) for SUV_max-LN ≥5.8; all patients with SUV_max-LN <5.8 were alive (p = 0.07). Median survival time was 28.2 months (range 21.7-34.7 months) for patients younger than 65 and 8.7 months (range 5.7-11.8 months) for those ≥65 years (p = 0.00).

CONCLUSIONS

Pre-treatment FDG-PET uptake may be a valuable tool to evaluate prognosis in SCLC patients. Patients with a higher pre-treatment FDG uptake may be considered at increased risk of failure and may benefit from more aggressive treatment approaches.

Clinical usefulness of 18F-FDG PET/CT for initial staging and assessment of treatment efficacy in patients with lymph node tuberculosis

INTRODUCTION

Few studies have evaluated the promising role of ¹⁸F-fluoro-2-deoxy-D-glucose positron emission tomography (PET) and PET/computed tomography FDG PET/CT in evaluating and monitoring treatment response in patients with lymph node tuberculosis (LNTB). The aim of this clinical investigation was to assess the clinical usefulness of FDG PET/CT for initial tuberculosis staging and to determine the prognostic value of the decrease of ¹⁸F-FDG uptake during antibiotic treatment in LNTB patients.

METHODS

We retrospectively reviewed 18 cases of LNTB admitted at a single center from 2004 to 2014. Medical records of patients who underwent two FDG PET/CT (>6 months interval), at initial staging and at the end of therapy were reviewed to determine the impact of FDG PET/CT on initial management of LNTB and response to therapy. Statistical analysis was performed using linear mixed-effects model.

RESULTS

Thirteen cases of disseminated LNTB and five cases of localized LNTB were included in the study. Initial FDG PET/CT allowed guided biopsy for initial diagnosis in 5 patients and identified unknown extra-LN TB sites in 9 patients. Visual analysis follow-up of FDG PET/CT showed a complete metabolic response in 9/18 patients (all of whom were cured), a partial response in 7/18 (5 of whom were cured) and no response in 2/18 (all of whom were not cured). The semi-quantitative evaluation of 18F-FDG intensity decrease based on the maximum standardized uptake value (SUVmax), compared to targeted estimated decrease allowed to predict correctly a complete response to treatment in 14/18 cases.

CONCLUSION

FDG PET/CT allows an accurate pre-therapeutic mapping of LNTB and helps for early TB confirmation. The SUVmax follow up is a potential tool for monitoring the treatment response.

Use of [(18)F]Fluoro-2-deoxy-d-glucose Positron Emission Tomographic Imaging in the National Lung Screening Trial

BACKGROUND

Positron emission tomography (PET) is a diagnostic tool for lung cancer evaluation. No studies have ascertained practice patterns and determined the appropriateness of PET imaging in a large group of US patients with screen-detected lung nodules.

METHODS

We analyzed participants in the National Lung Screening Trial (NLST) with positive screening test results and identified individuals with a PET scan performed prior to lung cancer diagnosis (diagnostic PET). Appropriate scan was defined as one performed in a patient with a nodule ≥ 0.8 cm. Logistic regression was used to assess factors associated with diagnostic PET scan use and appropriateness of PET scan use.

RESULTS

Diagnostic PET imaging was performed in 1,556 of 14,195 patients (11%) with positive screen results; 331 of these (21%) were inappropriate. PET scan use by endemic fungal disease area was comparable although patients from the Northeast/Southeast were twice as likely as the West to have a diagnostic PET. Trial arm, older age, sex, nodule size ≥ 0.8 cm, upper lobe location, and spiculated margin were variables positively associated with use. Trial arm, older age, and spiculated margin were positively associated with appropriate use. Only 561 diagnostic PETs (36%) were recommended by a radiologist and 284 PETs performed for nodules < 0.8 cm (86%) were ordered despite no recommendation from a radiologist.

CONCLUSIONS

PET imaging was differentially used in the NLST and inappropriately used in many cases against radiologist recommendations. These data suggest PET imaging may be overused in the lung cancer screening population and may contribute to excess health-care costs.

PET/CT, MR, and PET/MR in Lymphoma and Melanoma

With the introduction of hybrid imaging technologies such as PET/CT and recently PET/MRI, staging and therapy-response monitoring have evolved. PET/CT has been shown to be of value for routine staging of FDG-avid lymphomas before as well as at the end of treatment. For interim staging, trials are ongoing to evaluate the use of PET/CT. In melanoma, PET/CT can be recommended for stages III and IV diseases for initial staging and before surgery. Studies investigating the use of PET/CT for early therapy response are promising. The role of PET/MR in lymphoma and melanoma imaging has to be defined because no larger studies exist so far. There may be an application of PET/MR in research especially for tumor characterization and therapy response. Furthermore, the potential role of non-FDG tracers is elucidated regarding the assessment of treatment response in targeted drug regimens.

Dual time-point (18)F-FDG PET/CT to assess response to radiofrequency ablation of lung metastases

AIM

To establish the usefulness of dual time-point PET/CT imaging in determining the response to radiofrequency ablation (RFA) of solitary lung metastases from gastrointestinal cancer.

MATERIALS AND METHODS

This prospective study included 18 cases (3 female, 15 male, mean age 71±15 yrs) with solitary lung metastases from malignant digestive tract tumors candidates for RFA. PET/CT images 1h after injection of 4.07MBq/kg of (18)F-FDG (standard images) were performed at baseline, 1 month, and 3 months after RFA. PET/CT images 2h after injection centered in the thorax at 1 month after RFA were also performed (delayed images). A retention index (RI) of dual time-point images was calculated as follows: RI=(SUVmax delayed image-SUVmax standard image/SUVmax standard image)*100. Pathological confirmation of residual tumor by histology of the treated lesion was considered as local recurrence. A negative imaging follow-up was considered as complete response.

RESULTS

Local recurrence was found in 6/18 lesions, and complete response in the remaining 12. The mean percentage change in SUVmax at 1 month and at 3 months showed a sensitivity and specificity for PET/CT of 50% and 33%, and 67% and 92%, respectively. The RI at 1 month after RFA showed a sensitivity and specificity of 83% and 92%, respectively.

CONCLUSIONS

Dual time point PET/CT can predict the outcome at one month after RFA in lung metastases from digestive tract cancers. The RI can be used to indicate the need for further procedures to rule out persistent tumor due to incomplete RFA.

Plant-PET Scans: In Vivo Mapping of Xylem and Phloem Functioning

Medical imaging techniques are rapidly expanding in the field of plant sciences. Positron emission tomography (PET) is advancing as a powerful functional imaging technique to decipher in vivo the function of xylem water flow (with (15)O or (18)F), phloem sugar flow (with (11)C or (18)F), and the importance of their strong coupling. However, much remains to be learned about how water flow and sugar distribution are coordinated in intact plants, both under present and future climate regimes. We propose to use PET analysis of plants (plant-PET) to visualize and generate these missing data about integrated xylem and phloem transport. These insights are crucial to understanding how a given environment will affect plant physiological processes and growth.

Image-guided surgery using multimodality strategy and molecular probes

The ultimate goal of cancer surgery is to maximize the excision of tumorous tissue with minimal damage to the collateral normal tissues, reduce the postoperative recurrence, and improve the survival rate of patients. In order to locate tumor lesions, highlight tumor margins, visualize residual disease in the surgical wound, and map potential lymph node metastasis, various imaging techniques and molecular probes have been investigated to assist surgeons to perform more complete tumor resection. Combining imaging techniques with molecular probes is particularly promising as a new approach for image-guided surgery. Considering inherent limitations of different imaging techniques and insufficient sensitivity of nonspecific molecular probes, image-guided surgery with multimodality strategy and specific molecular probes appears to be an optimal choice. In this article, we briefly describe typical imaging techniques and molecular probes followed by a focused review on the current progress of multimodal image-guided surgery with specific molecular navigation. We also discuss optimal strategy that covers all stages of image-guided surgery including preoperative scanning of tumors, intraoperative inspection of surgical bed and postoperative care of patients.

PET-CT guided curative conformal radiation therapy in limited stage small cell lung cancer

BACKGROUND

The prognosis of small cell lung cancer (SCLC) has been improving with the advances in diagnostic and therapeutic modalities. Positron emission tomography/computed tomography (FDG-PET/CT) which has been studied in non-small cell lung cancer (NSCLC) for a long time, and it has only recently been applied to SCLC. Therefore we sought to observe firstly the prognostic importance of the FDG uptake in limited disease small cell lung cancer (LD-SCLC) patients and secondly the clinical outcomes and toxicity profiles of LD-SCLC patients treated with conformal radiation therapy (RT) using FDG-PET/CT simulation.

METHODS

Between 2009 and 2011, 33 LD-SCLC patients with LD-SCLC underwent disease staging using FDG-PET/CT conformal RT. Thoracic radiation was administered at a daily fraction of 2 Gy. Total dose was prescribed according to the treatment protocol such as, concurrent or sequential chemotherapy and in some patients according to the response of CT. All patients underwent chemotherapy. Survival was estimated using the Kaplan-Meier method.

RESULTS

The median age of the patients was 58 years (range, 38-77 years). The median follow-up time was 20 months (range, 6.6-47.6 months). The 3-year overall survival (OS) and locoregional control rates were 23% and 48%, respectively.

CONCLUSIONS

There are few studies examining the impact of PET-CT and the prognostic significance of FDG-uptake on outcomes in patients with LD-SCLC. Higher RT doses in response to higher FDG uptake may be safely applied for the purpose of locoregional control.

PET/CT in therapy evaluation of patients with lung cancer

FDG-PET/CT is a well documented and widespread used imaging modality for the diagnosis and staging of patient with lung cancer. FDG-PET/CT is increasingly used for the assessment of treatment effects during and after chemotherapy. However, PET is not an accepted surrogate end-point for assessment of response rate in clinical trials. The aim of this review is to present current evidence on the use of PET in response evaluation of patients with lung cancer and to introduce the pearls and pitfalls of the PET-technology relating to response assessment. Based on this and relating to validation criteria, including stable technology, standardization, reproducibility and broad availability, the review discusses why, despite numerous studies on response assessment indicating a possible role for FDG-PET/CT, PET still has no place in guidelines relating to response evaluation in lung cancer.

Clinical impact of contrast-enhanced computed tomography combined with low-dose (18)F-fluorodeoxyglucose positron emission tomography/computed tomography on routine lymphoma patient management

This study evaluated the clinical impact of contrast-enhanced computed tomography (CECT) on routine management of patients with lymphoma. Over a 1-year period, 237 CECT scans were performed prospectively in 163 patients after low-dose (18)F-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT). Scans were performed at staging (n = 41), interim (n = 73), post-therapy (n = 115) and follow-up (n = 8). Clinical impact was determined from the multidisciplinary committee reports. CECT had no clinical impact in 219 cases (92%). A clear impact was noted in only 3%, i.e. up-staging of lymphoma (n = 2) and diagnosis of deep vein thrombosis (n = 5). A debatable impact was noted in the remaining 11 cases, consisting of additional investigations, either without therapeutic impact (n = 8), or resulting in delay of therapy onset (n = 2) or ablative surgery (n = 1). CECT delivered an average 33.5 ± 3.8 mSv vs. 17.7 ± 2.8 mSv for PET/CT. In conclusion, the clinical impact of CECT seems limited, although scarce, life-threatening conditions were diagnosed. Imaging of lymphoma needs optimization to reduce radiation exposure.

Cost-effectiveness of Fluorine-18-Fluorodeoxyglucose positron emission tomography in tumours other than lung cancer: A systematic review

AIM: To systematically review published data on the cost-effectiveness of Fluorine-18-Fluorodeoxyglucose positron emission tomography (FDG-PET) or PET/computed tomography (PET/CT) in tumours other than lung cancer.

METHODS: A comprehensive literature search of studies published in PubMed/MEDLINE, Scopus and Embase databases through the 10^th of October in 2013 was carried out. A search algorithm based on a combination of the terms: (1) “PET” or “ PET/computed tomography (PET/CT)” or “positron emission tomography”; and (2) “cost-effectiveness” or “cost-utility” or “cost-efficacy” or “technology assessment” or “health technology assessment” was used. Only cost-effectiveness or cost-utility analyses in English language were included. Exclusion criteria were: (1) articles not within the field of interest of this review; (2) review articles, editorials or letters, conference proceedings; and (3) outcome evaluation studies, cost studies or health technology assessment reports. For each included study, information was collected concerning basic study, type of tumours evaluated, perspective/type of study, results, unit and comparison alternatives.

RESULTS: Sixteen studies were included. Head and neck tumours were evaluated in 4 articles, lymphoma in 4, colon-rectum tumours in 3 and breast tumours in 2. Only one article was retrieved for melanoma, oesophagus and ovary tumours. Cost-effectiveness results of FDG-PET or PET/CT ranged from dominated to dominant.

CONCLUSION: Literature evidence about the cost-effectiveness of FDG-PET or PET/CT in tumours other than lung cancer is still limited. Nevertheless, FDG-PET or PET/CT seems to be cost-effective in selective indications in oncology (staging and restaging of head and neck tumours, staging and treatment evaluation in lymphoma).

Molecular imaging for cancer diagnosis and surgery

Novel molecular imaging techniques have the potential to significantly enhance the diagnostic and therapeutic approaches for cancer treatment. For solid tumors in particular, novel molecular enhancers for imaging modalities such as US, CT, MRI and PET may facilitate earlier and more accurate diagnosis and staging which are prerequisites for successful surgical therapy. Enzymatically activatable "smart" molecular MRI probes seem particularly promising because of their potential to image tumors before and after surgical removal without re-administration of the probe to evaluate completeness of surgical resection. Furthermore, the use of "smart" MR probes as part of screening programs may enable detection of small tumors throughout the body in at-risk patient populations. Dual labeling of molecular MR probes with fluorescent dyes can add real time intraoperative guidance facilitating complete tumor resection and preservation of important structures. A truly theranostic approach with the further addition of therapeutic agents to the molecular probe for adjuvant therapy is conceivable for the future.

Role of positron emission tomography/computed tomography in breast cancer

Although positron emission tomography (PET) imaging may not be used in the diagnosis of breast cancer, the use of PET/computed tomography is imperative in all aspects of breast cancer staging, treatment, and follow-up. PET will continue to be relevant in personalized medicine because accurate tumor status will be even more critical during and after the transition from a generic metabolic agent to receptor imaging. Positron emission mammography is an imaging proposition that may have benefits in lower doses, but its use is limited without new radiopharmaceuticals.

Positron emission tomography of the vulnerable atherosclerotic plaque in man--a contemporary review

Atherosclerosis is the primary underlying cause of cardiovascular disease (CVD). It is the leading cause of morbidity and mortality in the Western world today and is set to become the prevailing disease and major cause of death worldwide by 2020. In the 1950s surgical intervention was introduced to treat symptomatic patients with high-grade carotid artery stenosis due to atherosclerosis – a procedure known as carotid endarterectomy (CEA). By removing the atherosclerotic plaque from the affected carotid artery of these patients, CEA is beneficial by preventing subsequent ipsilateral ischemic stroke. However, it is known that patients with low to intermediate artery stenosis may still experience ischemic events, leading clinicians to consider plaque composition as an important feature of atherosclerosis. Today molecular imaging can be used for characterization, visualization and quantification of cellular and subcellular physiological processes as they take place in vivo; using this technology we can obtain valuable information on atherosclerostic plaque composition. Applying molecular imaging clinically to atherosclerotic disease therefore has the potential to identify atherosclerotic plaques vulnerable to rupture. This could prove to be an important tool for the selection of patients for CEA surgery in a health system increasingly focused on individualized treatment. This review focuses on current advances and future developments of in vivo atherosclerosis PET imaging in man.

Early PET/CT scan is more effective than RECIST in predicting outcome of patients with liver metastases from colorectal cancer treated with preoperative chemotherapy plus bevacizumab

Markers predictive of treatment effect might be useful to improve the treatment of patients with metastatic solid tumors. Particularly, early changes in tumor metabolism measured by PET/CT with (18)F-FDG could predict the efficacy of treatment better than standard dimensional Response Evaluation Criteria In Solid Tumors (RECIST) response.

METHODS

We performed PET/CT evaluation before and after 1 cycle of treatment in patients with resectable liver metastases from colorectal cancer, within a phase 2 trial of preoperative FOLFIRI plus bevacizumab. For each lesion, the maximum standardized uptake value (SUV) and the total lesion glycolysis (TLG) were determined. On the basis of previous studies, a ≤ -50% change from baseline was used as a threshold for significant metabolic response for maximum SUV and, exploratively, for TLG. Standard RECIST response was assessed with CT after 3 mo of treatment. Pathologic response was assessed in patients undergoing resection. The association between metabolic and CT/RECIST and pathologic response was tested with the McNemar test; the ability to predict progression-free survival (PFS) and overall survival (OS) was tested with the Log-rank test and a multivariable Cox model.

RESULTS

Thirty-three patients were analyzed. After treatment, there was a notable decrease of all the parameters measured by PET/CT. Early metabolic PET/CT response (either SUV- or TLG-based) had a stronger, independent and statistically significant predictive value for PFS and OS than both CT/RECIST and pathologic response at multivariate analysis, although with different degrees of statistical significance. The predictive value of CT/RECIST response was not significant at multivariate analysis.

CONCLUSION

PET/CT response was significantly predictive of long-term outcomes during preoperative treatment of patients with liver metastases from colorectal cancer, and its predictive ability was higher than that of CT/RECIST response after 3 mo of treatment. Such findings need to be confirmed by larger prospective trials.

Reliability of a radiological grading system for dermal backflow in lymphoscintigraphy imaging

RATIONALE AND OBJECTIVES

Lymphoscintigraphy may be used for diagnosing secondary lymphedema. Dermal backflow, the presence of radiotracer in dermal lymphatics, is a key clinical feature. Although often reported as present or absent, a scale that assesses the severity of dermal backflow has been previously developed. The aim of this study was to determine the reliability of these two methods of assessment.

MATERIALS AND METHODS

Sixteen experienced nuclear medicine physicians assessed the quantity of dermal backflow of 57 lymphoscintigraphy scans using a 4-point descriptive scale that was dichotomized for secondary analysis. Each scan included images from four time points for women previously diagnosed with secondary lymphedema (n = 47) and controls (n = 5); five scans were presented twice to examine intraobserver reliability. This was further investigated as 13 physicians viewed the scans again on an Apple iPad2. The physicians rated their confidence in their scoring. Readers were blinded to clinical history.

RESULTS

Although both the 2- and 4-point scale had moderate interobserver reliability, the reliability of the 2-point scale was slightly higher (4-point: Fleiss κ = .418, standard error [SE] = .008); 2-point: Fleiss κ = .574, SE = .013). Low interobserver reliability was found when only control subjects were considered (Fleiss κ = 0.055, SE = 0.034). Intraobserver reliability of the five repeated images varied from poor to perfect (Cohen κ = .063 to 1.00), whereas moderate to substantial intraobserver reliability (Cohen's κ = .342 to .752) was found when comparing devices. The readers were highly confident of their scores.

CONCLUSIONS

Overall, moderate intraobserver and interobserver reliability was found for quantifying dermal backflow with both the 2- and 4-point scale.

PET/CT in Oncology: Current Status and Perspectives

The discovery of the Warburg effect in the early twentieth century followed by the development of the fluorinated glucose analogue 18F-fluorodeoxyglucose (18F-FDG) and the invention of positron emission tomographs laid the foundation of clinical PET/CT. This review discusses the challenges and obstacles in clinical adoption of this technique. We then discuss advances in instrumentation, including the critically important introduction of PET/CT and current PET/CT protocols. Moreover, we provide evidence for the clinical utility of PET/CT for patient management and its potential impact on patient outcome, and address its cost and cost-effectiveness. Although this review largely focuses on 18F-FDG imaging, we also discuss a variety of additional molecular imaging approaches that can be used for cancer phenotyping with PET. Throughout this review we emphasize the critical contributions of CT to the strength of PET/CT.

Followup of a solid solitary pulmonary nodule with low metabolic activity

An incidentally found solid solitary pulmonary nodule (SPN) was studied using FDG PET/CT. The SPN (at that time 11mm) showed only minimal FDG uptake, with a maximum standardized uptake value of 1.7 (max SUV). This suggested a benign lesion. When followup CT was performed six months later, the SPN had grown to 12mm. The patient was re-examined by FDG PET/CT five months later to exclude malignancy. The SPN was now FDG avid, and its size was 14mm. The max SUV was 12.7, consistent with a malignant disease. The patient underwent surgery, and histological examination demonstrated a solid adenocarcinoma (gradus III). The increase in glucose metabolism can be attributed to a change in the histopathologic subtype or molecular features of the SPN. The importance of a followup of nonmetabolically active SPNs is emphasized, primarily by CT (due to its convenience and low cost).

Improved Benefit of SPECT/CT Compared to SPECT Alone for the Accurate Localization of Endocrine and Neuroendocrine Tumors

Objective: To assess the clinical utility of SPECT/ CT in subjects with endocrine and neuroendocrine tumors compared to SPECT alone.

Material and Methods: 48 subjects (31 women;17 men; mean age 54±11) with clinical suspicion or diagnosis of endocrine and neuroendocrine tumor had 50 SPECT/CT scans (32 Tc-99m MIBI, 5 post treatment I-131, 8 In-111 Pentetreotide, and 5 I-123 MIBG). SPECT alone findings were compared to SPECT/CT and to pathology or radiological follow up.

Results: From the 32 Tc-99m MIBI scans, SPECT accurately localized the lesion in 22 positive subjects while SPECT/CT did in 31 subjects. Parathyroid lesions not seen on SPECT alone were smaller than 10 mm. In five post treatment I-131 scans, SPECT alone neither characterized, nor localized any lesions accurately. SPECT/CT revealed 3 benign etiologies, a metastatic lymph node, and one equivocal lesion. In 8 In-111 Pentetreotide scans, SPECT alone could not localize primary or metastatic lesions in 6 subjects all of which were localized with SPECT/CT. In five I-123 MIBG scans, SPECT alone could not detect a 1.1 cm adrenal lesion or correctly characterize normal physiologic adrenal uptake in consecutive scans of the same patient with prior history of adrenelectomy, all of which were correctly localized and characterized with SPECT/CT.

Conclusion: SPECT/CT is superior to SPECT alone in the assessment of endocrine and neuroendocrine tumors. It is better in lesion localization and lesion characterization leading to a decrease in the number of equivocal findings. SPECT/CT should be included in the clinical work up of all patients with diagnosis or suspicion of endocrine and neuroendocrine tumors.

Conflict of interest:None declared.

Imaging in oncology--over a century of advances

Over the past 120 years, the discipline of oncology has evolved so that a multitude of anatomical and increasingly complex functional imaging techniques are now applicable in both clinical and research platforms. This Timeline article revisits the achievements of the pioneer techniques in cancer imaging, discusses how these techniques have changed over time, provides some examples of clinical importance, and ventures to explain how imaging will remodel the future of modern oncology.

[Importance of PET/CT in lymphoma diagnostics]

CLINICAL/METHODICAL ISSUE

Staging or re-staging of lymphomas using conventional imaging modalities is based on morphological changes, usually on the diameter of lesions. However, vitality of tumors cannot be evaluated.

STANDARD RADIOLOGICAL METHODS

In this context computed tomography (CT) has been used as a standard modality.

METHODICAL INNOVATIONS

Since the introduction of positron emission tomography (PET), evaluation of tumor vitality has become possible. Moreover PET/CT hybrid scanners were brought onto the market one decade ago.

PERFORMANCE

The fluorodeoxyglucose (FDG) PET/CT technique is now accepted as one of the most accurate modalities in the diagnosis of aggressive lymphomas due to a high FDG uptake (overall accuracy > 90%, sensitivity >90%). However, indolent lymphomas suffer from lower FDG uptake due to a moderate metabolic activity. After the introduction of PET/CT hybrid imaging the specificity of this diagnostic technique increased significantly compared to PET alone (from > 80% to > 90%). With the utilization of PET approximately 20% more lesions are detected when comparing to CT alone and in up to 15% of the patients this also results in a change of the therapeutic regime. As post-chemotherapy scar tissue usually persists for months, evaluation of vitality within residual bulks using FDG-PET can predict therapy response much earlier than CT, enabling therapy stratification. Other PET tracers apart from FDG have low impact in imaging of lymphomas and only the thymidine analogue fluorothymidine (FLT) is used in some cases for non-invasive measurement of proliferation.

ACHIEVEMENTS

Despite the capability of FDG-PET/CT there is no evidence that the improvement in diagnostics is translated into a better patient outcome and therefore warrants the high costs. False positive findings in PET can result in unnecessary treatment escalation with subsequent higher therapy-associated toxicity and costs.

PRACTICAL RECOMMENDATIONS

Some pitfalls can be avoided by scheduling PET scans carefully. As treatment-induced inflammation early after therapy can be misinterpreted as vital tumor tissue, it is recommended to wait at least 3 weeks between the last treatment cycle and the subsequent FDG-PET follow-up. Until the results of the prospective multicenter trials "PETAL" and "HD-18" become available, in Germany FDG-PET is only recommended generally for restaging Hodgkin's disease with a known rest bulk of  > 2.5 cm in justifiable individual cases or in clinical trials.

Initial investigation of ¹⁸F-NaF PET/CT for identification of vertebral sites amenable to surgical revision after spinal fusion surgery

Purpose

A pilot study was performed in patients with recurrent back pain after spinal fusion surgery to evaluate the ability of ¹⁸F-NaF PET/CT imaging to correctly identify those requiring surgical intervention and to locate a site amenable to surgical intervention.

Methods

In this prospective study 22 patients with recurrent back pain after spinal surgery and with equivocal findings on physical examination and CT were enrolled for evaluation with ¹⁸F-NaF PET/CT. All PET/CT images were prospectively reviewed with the primary objective of identifying or ruling out the presence of lesions amenable to surgical intervention. The PET/CT results were then validated during surgical exploration or clinical follow-up of at least 15 months.

Results

Abnormal ¹⁸F-NaF foci were found in 16 of the 22 patients, and surgical intervention was recommended. These foci were located at various sites: screws, cages, rods, fixation hardware, and bone grafts. In 6 of the 22 patients no foci requiring surgical intervention were found. Validation of the results by surgery (15 patients) or on clinical follow-up (7 patients) showed that ¹⁸F-NaF PET/CT correctly predicted the presence of an abnormality requiring surgical intervention in 15 of 16 patients and was falsely positive in 1 of 16.

Conclusion

In this initial investigation, ¹⁸F-NaF PET/CT imaging showed potential utility for evaluation of recurrent symptoms after spinal fusion surgery by identifying those patients requiring surgical management.

Molecular imaging for personalized cancer care

Molecular imaging is rapidly gaining recognition as a tool with the capacity to improve every facet of cancer care. Molecular imaging in oncology can be defined as in vivo characterization and measurement of the key biomolecules and molecularly based events that are fundamental to the malignant state. This article outlines the basic principles of molecular imaging as applied in oncology with both established and emerging techniques. It provides examples of the advantages that current molecular imaging techniques offer for improving clinical cancer care as well as drug development. It also discusses the importance of molecular imaging for the emerging field of theranostics and offers a vision of how molecular imaging may one day be integrated with other diagnostic techniques to dramatically increase the efficiency and effectiveness of cancer care.

Whole-body FDG PET/CT is more accurate than conventional imaging for staging primary breast cancer patients

PURPOSE

This retrospective study aimed (1) to compare the diagnostic accuracy of whole-body FDG PET/CT for initial breast cancer staging with the accuracy of a conventional, multimodal imaging algorithm, and (2) to assess potential alteration in patient management based on the FDG PET/CT findings.

METHODS

Patients with primary breast cancer (106 women, mean age 57 ± 13 years) underwent whole-body FDG PET/CT and conventional imaging (X-ray mammography, MR mammography, chest plain radiography, bone scintigraphy and breast, axillary and liver ultrasonography). The diagnostic accuracies of FDG PET/CT and a conventional algorithm were compared. Diagnostic accuracy was assessed in terms of primary tumour detection rate, correct assessment of primary lesion focality, T stage and the detection rates for lymph node and distant metastases. Histopathology, imaging or clinical follow-up served as the standards of reference.

RESULTS

FDG PET/CT was significantly more accurate for detecting axillary lymph node and distant metastases (p = 0.0125 and p < 0.005, respectively). No significant differences were detected for other parameters. Synchronous tumours or locoregional extraaxillary lymph node or distant metastases were detected in 14 patients (13%) solely by FDG PET/CT. Management of 15 patients (14%) was altered based on the FDG PET/CT findings, including 3 patients with axillary lymph node metastases, 5 patients with extraaxillary lymph node metastases, 4 patients with distant metastases and 3 patients with synchronous malignancies.

CONCLUSION

Full-dose, intravenous contrast-enhanced FDG PET/CT was more accurate than conventional imaging for initial breast cancer staging due to the higher detection rate of metastases and synchronous tumours, although the study had several limitations including a retrospective design, a possible selection bias and a relevant false-positive rate for the detection of axillary lymph node metastases. FDG PET/CT resulted in a change of treatment in a substantial proportion of patients.