Impact of technology on the utilisation of positron emission tomography in lymphoma: current and future perspectives

Development and validation of a prognostic nomogram model in locally advanced NSCLC based on metabolic features of PET/CT and hematological inflammatory indicators

BACKGROUND

We combined the metabolic features of 18F-FDG-PET/CT and hematological inflammatory indicators to establish a predictive model of the outcomes of patients with locally advanced non-small cell lung cancer (LA-NSCLC) receiving concurrent chemoradiotherapy.

RESULTS

A predictive nomogram was developed based on sex, CEA, systemic immune-inflammation index (SII), mean SUV (SUVmean), and total lesion glycolysis (TLG). The nomogram presents nice discrimination that yielded an AUC of 0.76 (95% confidence interval: 0.66-0.86) to predict 1-year PFS, with a sensitivity of 63.6%, a specificity of 83.3%, a positive predictive value of 83.7%, and a negative predictive value of 62.9% in the training set. The calibration curves and DCA suggested that the nomogram had good calibration and fit, as well as promising clinical effectiveness in the training set. In addition, survival analysis indicated that patients in the low-risk group had a significantly longer mPFS than those in the high-risk group (16.8 months versus 8.4 months, P < 0.001). Those results were supported by the results in the internal and external test sets.

CONCLUSIONS

The newly constructed predictive nomogram model presented promising discrimination, calibration, and clinical applicability and can be used as an individualized prognostic tool to facilitate precision treatment in clinical practice.

Advancing Precision Nuclear Medicine and Molecular Imaging for Lymphoma

PET with fluorodeoxyglucose F 18 (¹⁸F FDG-PET) is a meaningful biomarker for the detection, targeted biopsy, and treatment of lymphoma. This article reviews the evolution of ¹⁸F FDG-PET as a putative biomarker for lymphoma and addresses the current capabilities, challenges, and opportunities to enable precision medicine practices for lymphoma. Precision nuclear medicine is driven by new imaging technologies and methodologies to more accurately detect malignant disease. Although quantitative assessment of response is limited, such technologies will enable a more precise metabolic mapping with much higher definition image detail and thus may make it a robust and valid quantitative response assessment methodology.

On transcending the impasse of respiratory motion correction applications in routine clinical imaging - a consideration of a fully automated data driven motion control framework

Positron emission tomography (PET) is increasingly used for the detection, characterization, and follow-up of tumors located in the thorax. However, patient respiratory motion presents a unique limitation that hinders the application of high-resolution PET technology for this type of imaging. Efforts to transcend this limitation have been underway for more than a decade, yet PET remains for practical considerations a modality vulnerable to motion-induced image degradation. Respiratory motion control is not employed in routine clinical operations. In this article, we take an opportunity to highlight some of the recent advancements in data-driven motion control strategies and how they may form an underpinning for what we are presenting as a fully automated data-driven motion control framework. This framework represents an alternative direction for future endeavors in motion control and can conceptually connect individual focused studies with a strategy for addressing big picture challenges and goals.

Clinical application of 18F-fluorodeoxyglucose positron emission tomography for assessment and evaluation after therapy for malignant hepatic tumor

Positron emission tomography (PET) is widely available and its application with 2-[(18)F] fluoro-2-deoxy-D-glucose ((18)F-FDG) in oncology has become one of the standard imaging modalities in diagnosing and staging of tumors, and monitoring the therapeutic efficacy in hepatic malignancies. Recently, investigators have measured glucose utilization in liver tumors using (18)F-FDG and positron emission tomography/computer tomography (PET/CT) in order to establish a diagnosis of tumors, assess their biologic characteristics and predict therapeutic effects on hepatic malignancies. The PET/CT with (18)F-FDG may further enhance the hepatic malignancy diagnostic algorithm by accurate diagnosis, staging, restaging and evaluating its biological characteristics, which can benefit the patients suffering from primary and metastatic hepatic tumors such as hepatocellular carcinoma (HCC), cholangiocarcinoma (CCC), and metastatic liver tumor.

Biological imaging in radiation therapy: role of positron emission tomography

In radiation therapy (RT), staging, treatment planning, monitoring and evaluation of response are traditionally based on computed tomography (CT) and magnetic resonance imaging (MRI). These radiological investigations have the significant advantage to show the anatomy with a high resolution, being also called anatomical imaging. In recent years, so called biological imaging methods which visualize metabolic pathways have been developed. These methods offer complementary imaging of various aspects of tumour biology. To date, the most prominent biological imaging system in use is positron emission tomography (PET), whose diagnostic properties have clinically been evaluated for years. The aim of this review is to discuss the valences and implications of PET in RT. We will focus our evaluation on the following topics: the role of biological imaging for tumour tissue detection/delineation of the gross tumour volume (GTV) and for the visualization of heterogeneous tumour biology. We will discuss the role of fluorodeoxyglucose-PET in lung and head and neck cancer and the impact of amino acids (AA)-PET in target volume delineation of brain gliomas. Furthermore, we summarize the data of the literature about tumour hypoxia and proliferation visualized by PET. We conclude that, regarding treatment planning in radiotherapy, PET offers advantages in terms of tumour delineation and the description of biological processes. However, to define the real impact of biological imaging on clinical outcome after radiotherapy, further experimental, clinical and cost/benefit analyses are required.

Active scheduling of organ detection and segmentation in whole-body medical images

With the advance of whole-body medical imaging technologies, computer aided detection/diagnosis (CAD) is being scaled up to deal with multiple organs or anatomical structures simultaneously. Multiple tasks (organ detection/segmentation) in a CAD system are often highly dependent due to the anatomical context within a human body. In this paper, we propose a method to schedule multi-organ detection/segmentation based on information theory. The central idea is to schedule tasks in an order that each operation achieves maximum expected information gain. The scheduling rule is formulated to embed two intuitive principles: (1) a task with higher confidence tends to be scheduled earlier; (2) a task with higher predictive power for other tasks tends to be scheduled earlier. More specifically, task dependency is modeled by conditional probability; the outcome of each task is assumed to be probabilistic as well; and the scheduling criterion is based on the reduction of the summed conditional entropy over all tasks. The validation is carried out on two challenging CAD problems, multi-organ detection in whole-body CT and liver segmentation in PET-CT. Compared to unscheduled and ad hoc scheduled organ detection/segmentation, our scheduled execution achieves higher accuracy with faster speed.

Value of positron emission tomography in staging ocular adnexal lymphomas and evaluating their response to therapy

BACKGROUND AND OBJECTIVE

An observational case series to assess the value of positron emission tomography (PET) in staging ocular adnexal lymphomas and evaluating their response to therapy.

PATIENTS AND METHODS

The clinical records of 16 consecutive patients with ocular adnexal lymphoma for whom pretreatment and posttreatment PET scans and corresponding computed tomography (CT) and magnetic resonance imaging (MRI) scans were available were compared.

RESULTS

Pretreatment PET scans demonstrated fluorine 18-fluorodeoxyglucose (FDG) positive lesions in 15 orbits of 12 patients. In 1 patient with low-grade follicular lymphoma of the orbit, PET revealed an additional focus of lymphoma in the deltoid muscle that was missed on clinical examination and conventional radiography. All of the posttreatment PET scans showed complete resolution of FDG uptake, suggesting good response to therapy. However, posttreatment CT and MRI scans demonstrated residual masses in 3 patients.

CONCLUSIONS

PET is valuable for initial staging of ocular adnexal lymphomas and may be a good adjunct to conventional imaging in evaluation of response to therapy.

Response of liver metastases after treatment with yttrium-90 microspheres: role of size, necrosis, and PET

OBJECTIVE

Yttrium-90 radioembolization is an emerging treatment for liver malignancies. The purpose of this study was to evaluate the imaging response of liver metastases to 90Y microspheres based on size and necrosis criteria using CT and comparing the results to PET and to describe imaging features related to 90Y therapy.

MATERIALS AND METHODS

We reviewed the imaging studies of 42 patients with unresectable liver metastases treated with lobar radioembolization with 90Y. CT response was determined using traditional size criteria (World Health Organization [WHO] and Response Evaluation Criteria in Solid Tumors [RECIST]), necrosis criteria, and combined criteria (RECIST and necrosis). We compared the response on CT with the response on PET. Complications of treatment were assessed.

RESULTS

The response rate was 19% (8/42) by WHO criteria, 24% (10/42) by RECIST, 45% (19/42) by necrosis criteria, and 50% (21/42) by combined criteria. Stabilization of lesion size occurred in 50% of patients. Necrosis and combined criteria identified responders earlier than RECIST and WHO criteria. Seven responders by combined criteria had an increase in lesion size on initial follow-up and would have been considered nonresponders. PET scans were obtained in 23 patients (33 treated lobes). PET detected significantly more responses to treatment (21/33, 63%) than CT using RECIST (2/33, 6%) or combined criteria (8/33, 24%) (p < 0.05, McNemar test). Complications of treatment included radiation cholecystitis (10 patients, 23%) and liver edema (18 patients, 42%).

CONCLUSION

The use of necrosis and size criteria on CT and correlation with PET may improve the accuracy of assessment of response to 90Y treatment in patients with liver metastases and detect response earlier than standard size criteria.

Applications of PET in Liver Imaging

Fluorodeoxyglucose PET (FDG-PET) imaging has an important role in determining if there are metastases to the liver and whether disease has spread beyond the liver. Such information is critical for planning surgical resections of liver metastases. The ability of FDG-PET quantitatively to estimate metabolic rates makes it an important tool for monitoring. With increasingly broad indications for FDG-PET imaging, it is expected that FDG-PET (and PET-CT) of the liver will play a growing and increasingly important role in detecting and monitoring treatment of tumors involving the liver.

Technology related parameters affecting quantification in positron emission tomography imaging

Some of the issues associated with positron emission tomography (PET) technology which still pose challenges for the recovery of quantitative images are discussed. Through these issues reference to what is today considered as the 'gold standard' in quantitative PET imaging is also presented. A brief comparison of 2-D and 3-D PET is given, together with a short discussion of combined PET/CT imaging devices.

Highlights of the Annual Congress of the European Association of Nuclear Medicine, Helsinki 2004, and a dash of horizon scanning

The Annual Congress of the European Association of Nuclear Medicine represents the major scientific and professional event in the field of nuclear medicine in Europe. Specialists from all allied professions meet to discuss the latest findings and discoveries. A very large industrial exhibition demonstrates the latest technological innovations and developments. This Highlights Lecture summarises the scientific and medical advances discussed at this important gathering. The lecture covers a significant proportion of the data presented and/or discussed in up-to-date reviews, and places some of the trends encountered in the context of the evolution of the field as a whole. There is much food for thought in most areas of nuclear medicine: advances in instrumentation and data processing, progress in radiochemistry and pharmacy, novel diagnostics and therapeutics, and new insights in known areas of clinical application such as neurology and psychiatry, cardiology, oncology, endocrine disorders, paediatrics, nephro-urology and musculoskeletal disorders. This Highlights Lecture is, however, only a brief resume of the vast amount of data discussed, which can be found in much greater detail in the Congress Proceedings, published as volume 31, supplement 2 of Eur J Nucl Med Mol Imaging in August 2004.

Predictive role of positron emission tomography (PET) in the outcome of lymphoma patients

An extensive analysis of the reliability of positron emission tomography (PET) after induction treatment in patients with Hodgkin's disease (HD) or aggressive non-Hodgkin's lymphoma (NHL). In all, 75 untreated patients with HD (n=41) or aggressive NHL (n=34) were studied with both PET and CT scans following standard chemotherapy induction therapy (ABVD or MACOP-B) with/without radiotherapy. Histopathological analysis was performed when considered necessary. After treatment, four out of five (80%) patients who were PET⁺/CT⁻ relapsed, as compared with zero out of 29 patients in the PET⁻/CT⁻ subset. Among the 41 CT⁺ patients, 10 out of 11 (91%) who were PET⁺ relapsed, as compared with 0 out of 30 who were PET⁻. The actuarial relapse-free survival (RFS) rates were 9 and 100% in the PET⁺ and PET⁻ subsets, respectively (P=0.00001). All five patients who were PET⁺/CT⁻ underwent a lymph node biopsy: in four (80%) cases, persistent lymphoma and was confirmed at histopathological examination. Two HD patients who were PET⁻/CT⁺ (with large residual masses in the mediastinum or lung) were submitted to biopsy, which in both cases revealed only fibrosis. In HD and aggressive NHL patients, PET positivity after induction treatment is highly predictive for the presence of residual disease, with significant differences being observable in terms of RFS. PET negativity at restaging strongly suggests the absence of active disease; histopathological verification is important in patients who show PET positivity.

Kombinierte Hybridsysteme (PET/CT, SPECT/CT) versus multimodale Bildgebung mit getrennten Systemen

With increasing use of combined PET/CT scanners in the last few years, multimodality imaging (Nuclear Medicine/Radiology) found its way into clinical routine diagnostics. In this overview, necessary components for multimodality imaging, strategies for image analysis and image presentation, and diagnostic goals of combined imaging are demonstrated and discussed. A special focus is on the question, whether combined scanners can be replaced by a software approach with separated modalities. Advantages and limitations of multimodality imaging with combined or separated scanners are shown.