Implications For Radiotherapy Planning Research Articles

Clinical Results of Fibroblast Activation Protein (FAP) Specific PET and Implications for Radiotherapy Planning: Systematic Review.

Simple SummaryThe purpose of this systematic review is to summarize the findings of using fibroblast activation protein (FAP) as a new tracer for positron emission tomography (PET) in cancer patients. In the 19 included studies, FAP was evaluated in various cancers and showed promising initial results for staging as well as radiotherapy planning. Small molecules targeting fibroblast activation protein (FAP) have emerged as a new group of tracers for positron emission tomography (PET) in 2018. The purpose of this systematic review is therefore to summarize the evidence that has been gathered to date in patients and to discuss its possible implications for radiotherapy planning. The MEDLINE database was searched for the use of FAP-specific PET in cancer patients and the records were screened according to PRISMA guidelines. Nineteen studies were included. While dedicated analyses of FAP-specific PET for radiotherapy planning were available for glioblastoma, head and neck cancers, lung cancer, and tumors of the lower gastrointestinal tract, there is still very limited data for several epidemiologically significant cancers. In conclusion, FAP-specific PET represents a promising imaging modality for radiotherapy planning that warrants further research.

OC-0560: FIESTA MRI to investigate CSF around lower cranial nerve roots; implications for radiotherapy planning

OC-0560: FIESTA MRI to investigate CSF around lower cranial nerve roots; implications for radiotherapy planning

Rectal tumour volume (GTV) delineation using T2-weighted and diffusion-weighted MRI: Implications for radiotherapy planning

PurposeTo compare the rectal tumour gross target volume (GTV) delineated on T2 weighted (T2W MRI) and diffusion weighted MRI (DWI) images by two different observers and to assess if agreement is improved by DWI. Material and methods27 consecutive patients (15 male, range 27.1–88.8 years, mean 66.9 years) underwent 1.5T MRI prior to chemoradiation (45Gy in 25 fractions; oral capecitabine 850mg/m2), including axial T2W MRI (TR=6600ms, TE=90ms) and DWI (TR=3000ms, TE=77ms, b=0, 100, 800s/mm2). 3D tumour volume (cm3) was measured by volume of interest (VOI) analysis by two independent readers for the T2W MRI and b800 DWI axial images, and the T2W MRI and DWI volumes compared using Mann–Whitney test. Observer agreement was assessed using Bland–Altman statistics. Significance was at 5%. ResultsArtefacts precluded DWI analysis in 1 patient. In the remaining 26 patients evaluated, median (range) T2W MRI MRI and DWI (b=800s/mm2) 3D GTVin cm3 were 33.97 (4.44–199.8) and 31.38 (2.43–228), respectively, for Reader One and 43.78 (7.57–267.7) and 42.45 (3.68–251) for Reader Two. T2W MRI GTVs were slightly larger but not statistically different from DWI volumes: p=0.52 Reader One; p=0.92 Reader Two. Interobserver mean difference (95% limits of agreement) for T2W MRI and DWI GTVs were −9.84 (−54.96 to +35.28) cm3 and −14.79 (−54.01 to +24.43) cm3 respectively. ConclusionSmaller DWI volumes may result from better tumour conspicuity but overall observer agreement is not improved by DWI.

Computed tomography overestimation of esophageal tumor length: Implications for radiotherapy planning

To assess the relationship between preoperative computed tomography (CT) and postoperative pathological measurements of esophageal tumor length and the prognostic significance of CT tumor length data. A retrospective study was carried out in 56 patients who underwent curative esophagogastrectomy. Tumor lengths were measured on the immediate preoperative CT and on the post-operative resection specimens. Inter- and intra-observer variations in CT measurements were assessed. Survival data were collected. There was a weak correlation between CT and pathological tumor length (r = 0.30, P = 0.025). CT lengths were longer than pathological lengths in 68% (38/56) of patients with a mean difference of 1.67 cm (95% CI: 1.18-2.97). The mean difference in measurements by two radiologists was 0.39 cm (95% CI: -0.59-1.44). The mean difference between repeat CT measured tumor length (intra-observer variation) were 0.04 cm (95% CI: -0.59-0.66) and 0.47 cm (95% CI: -0.53-1.47). When stratified, patients not receiving neoadjuvant chemotherapy showed a strong correlation between CT and pathological tumor length (r = 0.69, P = 0.0014, n = 37) than patients that did (r = 0.13, P = 0.43, n = 19). Median survival with CT tumor length > 5.6 cm was poorer than with smaller tumors, but the difference was not statistically significant. Esophageal tumor length assessed using CT does not reflect pathological tumor extent and should not be the only modality used for management decisions, particularly for planning radiotherapy.

CT overestimates oesophageal tumour length particularly after neoadjuvant chemotherapy: implications for radiotherapy planning

Introduction: Tumour length is an adverse prognostic factor in oesophageal cancer and successful treatment depends on accurate preoperative assessment. This study assessed the level of agreement between preoperative CT and postoperative pathological measurements of oesophageal tumour length, and the relationship between CT tumour length and prognosis.

Macroscopic tumor volume of malignant glioma determined by contrast-enhanced magnetic resonance imaging with and without magnetization transfer contrast

The purposes of this study were to compare the conspicuity and lesion volume of contrast-enhancing macroscopic malignant glioma determined by postcontrast magnetic resonance (MR) imaging with and without magnetization transfer (MT) saturation, and to discuss possible implications for radiotherapy planning. Nineteen patients (age 24–60 years) with histologically proven malignant glioma were prospectively examined by MR imaging. After the administration of gadolinium dimeglumine (0.1 mmol/kg body weight), the lesions were imaged with an MT-weighted FLASH (fast, low-angle shot) pulse sequence and with a conventional T 1-weighted spin-echo (SE) sequence without MT saturation. The mean tumor volumes of gliomas measured on MT-weighted FLASH images were significantly ( p < .01) larger than those obtained from T 1-weighted SE images (45 ± 15 cm 3 vs. 33 ± 10 cm 3). The mean contrast-to-noise ratio of enhancing lesions on MT-weighted FLASH was 48 ± 14 compared with 30 ± 14 on SE images, representing a significant ( p < .01) improvement. We conclude that the volume of contrast enhancement of malignant glioma identified on MT-weighted FLASH images represents the area of disrupted blood-brain barrier. If this volume of subtle contrast enhancement is caused by tumor infiltration and represents the boost target volume for stereotactic radiosurgery or brachytherapy, MT-weighted FLASH images would be better than T 1-weighted SE images to define these volumes. These improved delineation of areas at highest risk for recurrence following radiation therapy should enhance the efficacy of treatment planning for high-boost therapy.

The role of CT in the staging and radiotherapy planning of prostatic tumours.

Fifty patients with proven carcinoma of the prostate have been evaluated with CT. The CT studies were carried out for staging and radiotherapy planning and the findings compared with rectal examination and lymphography. CT provided useful additional information to that obtained by rectal examination in 40% of patients and these findings had important implications for radiotherapy planning. There was good correlation between CT and lymphography in the assessment of pelvic lymph node involvement.