Does Extended PET Acquisition in PET/MRI Rectal Cancer Staging Improve Results?

Bailey, Jason J.; Jordan, Eric; Burke, Colin; Ohliger, Michael A.; Wang, Z Jane; Loon, Katherine Van; Varma, Madhulika G.; Hope, Thomas A.

doi:10.2214/ajr.18.19620

Cited by 26 publications

(24 citation statements)

References 28 publications

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“…Attempts to develop improved accuracy are desirable as the assessment of N-stage remains challenging in rectal cancer [ 2 , 3 , 5 – 8 ]. In a recent study, Baily et al show that PET/MRI identified 94 hypermetabolic nodal structures presumed to be lymph nodes in 29 patients with rectal cancer, where approximately 61% of the metabolically abnormal lymph nodes had a size of 5 mm or less [ 20 ]. While the study lacked histopathological matching, the findings suggest that the assessment of mesorectal nodal structures could be facilitated with the aid of the metabolic information from FDG-PET/MRI.…”

Section: Discussionmentioning

confidence: 99%

“…in the head-and-neck region, brain, pelvis, breast, and in paediatric oncology [ 13 , 14 ]. Few studies have evaluated the role of 18 F-fluoro-2-deoxy-D-glucose (FDG) PET/MRI in colorectal cancer and even fewer in patients with primary rectal cancer [ 15 – 20 ]. None of these studies have matched individual nodal structures anatomically with a histopathological analysis, which is of importance for a valid comparison of imaging and histopathology.…”

Section: Introductionmentioning

confidence: 99%

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Rectal cancer: a methodological approach to matching PET/MRI to histopathology

et al. 2020

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Purpose To enable the evaluation of locoregional disease in the on-going RECTOPET (REctal Cancer Trial on PET/MRI/CT) study; a methodology to match mesorectal imaging findings to histopathology is presented, along with initial observations. Methods FDG-PET/MRI examinations were performed in twenty-four consecutively included patients with rectal adenocarcinoma. In nine patients, of whom five received neoadjuvant treatment, a postoperative MRI of the surgical specimen was performed. The pathological cut-out was performed according to clinical routine with the addition of photo documentation of each slice of the surgical specimen, meticulously marking the location, size, and type of pathology of each mesorectal finding. This allowed matching individual nodal structures from preoperative MRI, via the specimen MRI, to histopathology. Results Preoperative MRI identified 197 mesorectal nodal structures, of which 92 (47%) could be anatomically matched to histopathology. Of the matched nodal structures identified in both MRI and histopathology, 25% were found to be malignant. These malignant structures consisted of lymph nodes (43%), tumour deposits (48%), and extramural venous invasion (9%). One hundred eleven nodal structures (55%) could not be matched anatomically. Of these, 97 (87%) were benign lymph nodes, and 14 (13%) were malignant nodal structures. Five were malignant lymph nodes, and nine were tumour deposits, all of which had a short axis diameter < 5 mm. Conclusions We designed a method able to anatomically match and study the characteristics of individual mesorectal nodal structures, enabling further research on the impact of each imaging modality. Initial observations suggest that small malignant nodal structures assessed as lymph nodes in MRI often comprise other forms of mesorectal tumour spread. Trial registration Clinical Trials Identifier:NCT03846882.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Rectal cancer: a methodological approach to matching PET/MRI to histopathology

et al. 2020

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“…However, to our knowledge, an association between extended PET acquisition time and increased number of false positives has not been reported previously. A single study that considered the effect of extended PET acquisition time during PET/MRI staging of rectal cancer reported a greater lymph node detection rate for 15‐minute versus 3‐minute acquisitions but the lack of a reference standard prevented assessment of false‐positive rates . The prevalence of inflammatory lymph nodes relative to malignancy at staging is likely to be low in comparison to post‐treatment imaging.…”

Section: Discussionmentioning

confidence: 99%

Discrepancies between positron emission tomography/magnetic resonance imaging and positron emission tomography/computed tomography in a cohort of oncological patients

O'Mahoney

Jeavons

et al. 2020

J Med Imag Rad Onc

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Introduction: This study aims to evaluate discrepant findings between positron emission tomography/magnetic resonance imaging (PET/MRI) and positron emission tomography/computed tomography (PET/CT) in a cohort of oncological patients and to undertake a phantom study to assess the potential for extended PET acquisitions to lead to false-positive findings on PET/MRI. Methods: Discrepant findings from a series of 106 patients undergoing sameday 18 F-fluorodeoxyglucose (FDG)-PET/CT and PET/MRI were reviewed. Phantom studies explored the potential for PET acquisition time to contribute to discrepancy.Results: There were 14 discrepant cases, 5 (35.7%) of which related to PET/ MRI acquisitions that had been extended to 10 min. Three of these five cases proved to be falsely positive. Phantom studies showed greater contrast recovery and signal to noise ratio for 10-min PET/MRI acquisitions compared to 2min acquisitions using PET/CT. There were no discrepancies when PET/CT showed disseminated disease (P = 0.036). Conclusions: Extended PET/MRI acquisitions used to accommodate multiple MRI sequences may be associated with false-positive findings compared to PET/CT. PET/MRI is more likely to have incremental value when the prior probability for disseminated disease is low.

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“…The presence of numerous rectal cancer postoperative bed morphological changes offer a great challenge during serial follow-up of the rectal cancer post-operative patients; similar morphological patterns are noted in the normal post-operative fields as well as the evolving residual/recurrent neoplastic process. Differentiation of post-therapeutic alterations attributable to scarring, inflammation, and necrosis from residual or recurrent tumors poses significant problems for CT [9].…”

Section: Discussionmentioning

confidence: 99%

Rectal operative bed: ?tumor? post-management changes … positron emission tomography/computed tomography (PET/CT) can answer

Abdelmohsen

Omar

Shaaban

2020

Egypt J Radiol Nucl Med

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Background: Rectal cancer is a common malignancy that continues to have a highly variable outcome. Local pelvic recurrence following surgery is usually leading to incurable disease. Surgical resection with stage-appropriate combinedmodality therapy is the mainstay in the treatment of rectal cancer. A difficulty has been reported in distinguishing the benign post-management findings from tumor recurrence. By adding the metabolic changes to the post-operative morphologic changes, combined positron emission tomography (PET) and computed tomography (CT) may offer clinically useful addition in operative bed evaluation. Results: The study included 30 patients, 17 males (56.6%) and 13 females (43.3%). Suspicious operative bed findings included pre-sacral soft tissue density noted in 20 patients (66%), anastomotic site mural thickening in five patients (16.6%), and post-operative loco-regional nodes in five patients (16.6%). Moreover, pre-sacral soft tissue focal avid uptake was noted in 17 patients (17/20, 85%), and no uptake noted in three patients (3/20, 15%). Anastomotic site mural thickening was seen in five patients with positive uptake noted in three patients (3/5, 60%), and no uptake seen in two patients (2/5, 40%). Loco-regional nodes were seen in five patients with positive uptake in five patients. The most accurate SUV max cutoff value among studied cases was 3.5. Confirmation of PET/CT results was done by histopathological assessment in ten patients (33.3%) and by follow up after 6 months in 20 patients (66.6%) with recurrence noted in 15 patients (75%) and normal post-operative findings noted in five patients (25%). Conclusion: PET/CT study is an effective tool for evaluation of suspicious colorectal oncologic operative bed findings noted in the routine CT studies. PET/CT fusion images affect the clinical management by guiding further procedures (surgery and radiation therapy).

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Does Extended PET Acquisition in PET/MRI Rectal Cancer Staging Improve Results?

Abstract: Longer PET acquisition times during PET/MRI for rectal cancer increases the number of FDG-avid lymph nodes detected without increasing scan time.

Cited by 26 publications

References 28 publications

Rectal cancer: a methodological approach to matching PET/MRI to histopathology

Rectal cancer: a methodological approach to matching PET/MRI to histopathology

Discrepancies between positron emission tomography/magnetic resonance imaging and positron emission tomography/computed tomography in a cohort of oncological patients

Rectal operative bed: ?tumor? post-management changes … positron emission tomography/computed tomography (PET/CT) can answer

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