Cancer Treatment Today » Imaging

How to follow brain metastases after radiosurgery – pro

M Levin, MD — Thu, 22 Nov 2012 15:15:17 +0000

How to follow a patient with treated brain metastases is becoming a more and more actual clinical problem as treatments that control systemic disease continue to improve. It is not uncommon now to follow a patient for many months or even years after treatment of metastatic disease without new metastases developing. One study reported a median time of 8.8 months to new metastasis after radiosurgery. Patients with 3 or more lesions and cancer histologies other than NSCLC were more likely to have additional future metastasis. This data produced a recommendation for close surveillance with a 3-month interval between magnetic resonance imaging (MRI), in order to identify new metastasis early to facilitate the most effective treatment. However, the most appropriate frequency and choice of imaging modality following treatment of a patient with brain metastases remain controversial. As the most sensitive current imaging modality for the brain, MRI is the preferred imaging modality, even with an newer applications such as spectroscopy, diffusion-weighted imaging, and perfusion-weighted imaging.

A. Mintz, MD et al, Management of single brain metastasis: a practice guideline. Curr Oncol. 2007 August; 14(4): 131–143.

Patel SH, Robbins JR, Videtic GM, Gore EM, Bradley JD, Gaspar LE, Germano I, Ghafoori P, Henderson MA, Lutz ST, McDermott MW, Patchell RA, Robins HI, Vassil AD, Wippold FJ II, Expert Panel on Radiation Oncology-Brain Metastases. ACR Appropriateness Criteria® follow-up and retreatment of brain metastases. [online publication]. Reston (VA): American College of Radiology (ACR); 2011. 8 p. [33 references]

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PET for glioblastoma – pro

M Levin, MD — Fri, 24 Aug 2012 18:05:03 +0000

PET is not medically appropriate to follow glioblastoma because it not supported by credible scientific evidence published in peer-reviewed medical literature generally and recognized by the relevant medical community. PET for brain cancer is not included in the NCCN guidelines and CMS does not cover PET for this diagnosis. Occasionally, PET can provide information to differentiate tumor necrosis from tumor progression. The sensitivity of PET for differentiating necrosis and tumor progression is 80%–90% and the specificity is 50%–90%. Causes of false-negative PET results include recent radiation therapy, low histologic grade, and small tumor volume. FDG PET may be false positive in nonmalignant inflammatory processes and subclinical seizure activity. The question of hypermetabolic foci of radiation injury as a cause of false-positive scans requires further investigation. Other issues requiring further study are the optimal timing of FDG PET after radiation and chemotherapy and the accuracy of FDG PET in tumors other than high-grade gliomas.

A 2010 guideline by Laperrier says: Positron emission tomography (PET) is not recommended for the determination of diagnosis or grading in gliomas. A recommendation cannot be made for or against the use of PET or positron emission tomography/computed tomography (PET/CT) in the assessment of patients with recurrent gliomas because of insufficient evidence. Positron emission tomography (PET) is not recommended for the determination of diagnosis or grading in gliomas. A recommendation cannot be made for or against the use of PET for the assessment of treatment response in gliomas because of insufficient evidence. A recommendation cannot be made for or against the use of PET or positron emission tomography/computed tomography (PET/CT) in the assessment of patients with recurrent gliomas because of insufficient evidence. Positron emission tomography (PET) is not recommended for the determination of diagnosis or grading in gliomas. A recommendation cannot be made for or against the use of PET for the assessment of treatment response in gliomas because of insufficient evidence. A recommendation cannot be made for or against the use of PET or positron emission tomography/computed tomography (PET/CT) in the assessment of patients with recurrent gliomas because of insufficient evidence.
The situation is different if pseudoprogression or radiation necrosis ii being considered. There, NCCN GLIO-4 recommends MR Spectroscopy, PET or MR Perfusion, footnote S.

D. A. Podoloff PET/CT and Occult Primary Tumors J Natl Compr Canc Netw, March 1, 2009; 7(3): 239 – 244.

Laperriere N, Walker-Dilks C. PET imaging in brain cancer: recommendations. Toronto (ON): Cancer Care Ontario (CCO); 2009 Jan 19. 13 p. (Recommendation report – PET; no. 10). [14 references]

nccn, brain cancers, 2012

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Radiologic follow-up of pituitary tumors – pro

M Levin, MD — Fri, 24 Aug 2012 17:51:46 +0000

Pituitary tumors are classified as micoradenomas, sometimes called incidentalomas, because they tend to be asymptomatic and discovered incidentally, and macroadenomas. BMJ Best PRactice (2012) says that there is no consensus about the follow-up duration of patients with non-functional pituitary microadenomas, but recommends a follow-up MRI in 1 year with no further routine imaging study if the tumour is stable, especially in those with a pituitary microadenoma < 6 mm in size, unless the patient develops symptoms or signs suggestive of mass effect.

The risk of tumour growth for pituitary macroadenomas is expected to be higher since the tumour has already shown the propensity to grow. There is no consensus, but a pragmatic approach would be to obtain a follow-up MRI at 6 months and then yearly for 5 years. This can be followed by an imaging study every 2 to 3 years if the pituitary tumour is stable. This recommendation is in line with that of the Endocrine Society and Best Practice.

Biochemchemical and laboratory followup is not discussed in this review of radiologic followup.

http://bestpractice.bmj.com/best-practice/monograph/1030/follow-up.html, 2012

http://www.endo-society.org/guidelines/upload/032811_PituitaryIncident_FinalA-2.pdf

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