Assessment of response to treatment
Anju Sahdev, Sarah J. Vinnicombe in Husband & Reznek's Imaging in Oncology, 2020
A general principle to follow in imaging of response assessment is that the subsequent follow-up examinations should be performed with the same modality and the same imaging protocol. This enables comparison of the size and number of lesions, as well other, more recently introduced, metabolic and functional parameters. The introduction of new modalities or imaging of new body parts should be performed if there are equivocal features on initial imaging or if new clinical symptoms are present. Generally, there is now a trend towards whole-body imaging in cancer that provides all necessary information for patient management in a single examination. Increasingly, radiologists participate in clinical investigations or clinical trials involving novel imaging or therapeutic agents to assess their efficacy. General guidelines regarding good clinical practice are appropriate in these research investigations, as well as for those undertaken in routine clinical practice and, at present, the greatest difference lies in the degree of quantification of imaging findings between research and clinical studies, as well as the documentation of the findings. Ultimately, accurate interpretation of the imaging findings and individual patient care are paramount, whether involving a routine case or a clinical research investigation.
PET/microPET Imaging
Robert J. Gropler, David K. Glover, Albert J. Sinusas, Heinrich Taegtmeyer in Cardiovascular Molecular Imaging, 2007
The coincidence events detected by a PET scanner can be divided into three categories (Fig. 7). If the annihilation photons escape the object without any interaction and subsequently become detected by the scanner, this is defined as a true coincidence, illustrated as event A. If at least one of the two 511 keV photons is scattered by the object, such as event B in Figure 7, this is a scattered coincidence. If two uncorrelated 511 keV photons are detected within the predefined timing window, shown as event C, it is a random coincidence. True coincidences are the desired signal and are proportional to the amount of activity within the field of view (FOV). Scatter coincidences are proportional to the activity within and near the FOV, but also depend on the amount of scattering medium that annihilation photons encounter. For human imaging, particularly the whole-body imaging protocol, this can be a significant portion of the total coincidences measured by a scanner. Random coincidences are proportional to the width of the coincidence timing window and the square of the singles event rate of detectors. That is, when the amount of activity within and near the FOV doubles, the random coincidences increase by nearly a factor of 4. Both scatter and random coincidences need to be subtracted from the measured coincidences before the images are reconstructed.
Image Acquisition Protocols
Michael Ljungberg in Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
As discussed, it is possible to reduce the FOV used by the system by applying a digital zoom during the acquisition. Conversely, it is possible to increase the field of view by moving the detector or patient during an acquisition. This type of acquisition protocol is generally referred to as whole-body imaging, as it is commonly used to image along the entire length of the patient. A clinical example where this is most common is for bone imaging, particularly for oncology where potential sites of disease can appear in any number of places within the skeletal anatomy. Typical imaging methods and patient preparation are summarized in Table 15.5.
Primary cardiac lymphoma: the management and outcome of a single-centre cohort of 22 patients
Published in Acta Oncologica, 2021
Xiao-Juan Wei, Hui Yuan, Pek-Lan Khong, Fen Zhang, Peng-Jun Liao, Xin-Miao Jiang, Ling Huang, Han-Guo Guo, Fei-Li Chen, Si-Chu Liu, Yan-Ying Huang, Shu-Xia Wang, Wen-Yu Li
Whole-body imaging was performed to evaluate disease characteristics and determine the optimal biopsy route. Whole-body 18-fluorodeoxyglucose positron emission tomography/computed tomography (18 F-FDG PET/CT) combined with contrast-enhanced CT (CECT) was the imaging modality of choice, but for patients with limited economic resources whole-body CECT was also accepted (see Document S1 for a description of the imaging techniques). Bulky disease was defined as the largest dimension ≥7.5 cm of a cardiac tumour. If imaging revealed extracardiac involvement, biopsy was performed at the least invasive site. Peripheral lymph node or mass biopsy was the priority, followed by cytological investigation of pleural or pericardial effusion, and intrathoracic or intra-abdominal biopsy (mediastinoscopy or CT-guided fine needle aspiration biopsy [CT-FNAB]). For patients presenting with only intrapericardial lesions, we attempted transjugular endocardial biopsy, endobronchial ultrasonography-guided fine-needle aspiration biopsy (EBUS-FNAB), or video-assisted thoracic surgery (VATS), depending on the lesion location. Cardiotomy was the final option. All histological samples were reviewed by an experienced pathologist (F Z) as previously described [13].
Pathway to biomarker discovery in psoriatic arthritis
Published in Expert Review of Clinical Immunology, 2020
Biomarker research in a heterogeneous disease within another disease (PsA occurs within a larger population of psoriasis patients) is challenging. The immediate challenge is defining clinical outcomes. Although the CASPAR classification criteria have helped standardize the classification of PsA, the mandatory or stem criterion – inflammatory musculoskeletal disease – remains poorly defined [10,74]. Criteria for joint damage based on erosion and joint space narrowing have been defined; those for new bone formation are not commonly used [75]. These changes are slow to develop and strongly influenced by baseline damage and treatment. Designing an adequately powered study to validate biomarkers for joint damage is therefore difficult. In PsA, there is often poor correlation between physician assessment, patient-reported outcomes and imaging studies [76,77]. The current criteria for disease activity and treatment response are composite measures that include physician-assessed, patient-reported, and common laboratory test(s). Although useful for clinical trials and observational studies, these criteria may not be ideal for biomarker discovery studies. Criteria anchored in whole body imaging methods may be required at least for discovery studies.
Cemiplimab for locally advanced cutaneous squamous cell carcinoma: safety, efficacy, and position in therapy panel
Published in Expert Review of Anticancer Therapy, 2021
Eve Lebas, Nathalie Marchal, Andrée Rorive, Arjen F Nikkels
The cornerstone study revealed that using cemiplimab at 3 mg/kg every 2 weeks for expansion cohorts of patients suffering from lacSCC and/or mcSCC in a phase 1 trial, a response rate of 50%, observed after 2 months of treatment (13 of 26 patients, 95% confidence interval (CI), 30 to 70)(NCT02383212) [32]. Efficacy was evaluated using whole-body imaging techniques according to RECIST 1.1. In a pivotal phase 2 study with a median follow-up of 7.9 months it was demonstrated that 3 mg/kg of cemiplimab every 2 weeks for a cohort of patients with mcSCC provided a response rate of 47% (28 of 59 patients; 95% CI, 34 to 61) [32]. Among the 28 responding patients the DOR was longer than half a year in 57% of the patients, and 82% of the responding patients continued to have a response and to receive cemiplimab at the time of data cutoff [33].
Related Knowledge Centers
- Medical Imaging
- Full-Body CT Scan
- Magnetic Resonance Imaging
- Full Body Scanner