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02-02-2006, 08:25 AM

Mickey:
I believe the reason for pet is to determine active cancer or benign necrotic tissue. I do know there is an MRi/Pet type scan that can do this. Will include info here.
hugs,
pattyz

Performed together, MRI and MRS (magnetic resonance spectroscopy) produce an image of the brain that shows both morphology and tissue metabolism. Certain metabolites are present in greater or lesser quantities in tumors, compared to normal brain tissue. Choline is a cell-member marker that is found in increased quantities in malignant tumors.

BACKGROUND: There have been some reports that radiation necrosis can be controlled conservatively. There are rare cases showing progressive space-occupying radiation necrosis (PSORN). It is very difficult to control PSORN by conservative treatment. The purpose of this study was to evaluate the early diagnosis of those cases and the timing of surgery for patients with PSORN. METHOD: We have experienced some cases where quality of life was improved by the removal of PSORN after stereotactic radiosurgery (SRS) for brain metastases. Therefore, we evaluated retrospectively the diagnosis and treatment of six cases of symptomatic PSORN at approximately 6-12 months after SRS for metastatic brain tumours. FINDINGS: In all six cases, on Magnetic Resonance Imaging with Gd contrast material (Gd-MRI), PSORN was revealed as a ring-like enhanced mass with large perifocal oedema coupled with the appearance of neurological deficit. Proton Magnetic Resonance Spectroscopy ((1)H-MRS) enabled us to differentiate PSORN from recurrence of metastases in all six cases.

MRS Applications in Oncology
By Pia C. Sundgren MD, PhD, Suresh K. Mukherji MD
Lately, MRS has been shown to be a helpful tool in evaluation of a new contrast-enhancing lesion at the site of a previously identified and treated primary intracranial neoplasm, differentiating recurrent tumor from radiation injury.

Radiation injury versus recurrent brain tumor . Contrast-enhancing lesions that arise on routine brain MR imaging at the site of a previously identified and treated primary intracranial neoplasm present a significant diagnostic dilemma. These lesions are in regions that have been subjected to radiation, with or without chemotherapy, and in some instances surgical resection. Many do not have specific imaging characteristics that will enable the neuroradiologist to discriminate tumor recurrence from the inflammatory or necrotic changes that can result from treatment with radiation. 28 Both recurrent tumors and radiation injury typically demonstrate enhancement with gadolinium. Specific spectroscopic changes that occur with radiation-induced necrosis have been reported and include slight depression of NAA and variable changes in choline. 29-32 A recent study reported a 93% success rate in differentiating recurrent tumor from radiation injury with significantly increased Cho/NAA and Cho/Cr ratios (P < 0.001) in areas of recurrent tumor compared to areas of radiation injury and compared to normal adjacent brain tissue. 33 These results also are supported by previous work utilizing SVS, where the authors claim that a Cho/Cr ratio over 1.79 or lipid-lactate/Cho ratio less than 0.75 has a sevenfold increased odds of indicating tumor compared to pure necrosis.

02-02-2006, 08:25 AM	#20
pattyz Guest Posts: n/a	Mickey: I believe the reason for pet is to determine active cancer or benign necrotic tissue. I do know there is an MRi/Pet type scan that can do this. Will include info here. hugs, pattyz Performed together, MRI and MRS (magnetic resonance spectroscopy) produce an image of the brain that shows both morphology and tissue metabolism. Certain metabolites are present in greater or lesser quantities in tumors, compared to normal brain tissue. Choline is a cell-member marker that is found in increased quantities in malignant tumors. BACKGROUND: There have been some reports that radiation necrosis can be controlled conservatively. There are rare cases showing progressive space-occupying radiation necrosis (PSORN). It is very difficult to control PSORN by conservative treatment. The purpose of this study was to evaluate the early diagnosis of those cases and the timing of surgery for patients with PSORN. METHOD: We have experienced some cases where quality of life was improved by the removal of PSORN after stereotactic radiosurgery (SRS) for brain metastases. Therefore, we evaluated retrospectively the diagnosis and treatment of six cases of symptomatic PSORN at approximately 6-12 months after SRS for metastatic brain tumours. FINDINGS: In all six cases, on Magnetic Resonance Imaging with Gd contrast material (Gd-MRI), PSORN was revealed as a ring-like enhanced mass with large perifocal oedema coupled with the appearance of neurological deficit. Proton Magnetic Resonance Spectroscopy ((1)H-MRS) enabled us to differentiate PSORN from recurrence of metastases in all six cases. MRS Applications in Oncology By Pia C. Sundgren MD, PhD, Suresh K. Mukherji MD Lately, MRS has been shown to be a helpful tool in evaluation of a new contrast-enhancing lesion at the site of a previously identified and treated primary intracranial neoplasm, differentiating recurrent tumor from radiation injury. Radiation injury versus recurrent brain tumor . Contrast-enhancing lesions that arise on routine brain MR imaging at the site of a previously identified and treated primary intracranial neoplasm present a significant diagnostic dilemma. These lesions are in regions that have been subjected to radiation, with or without chemotherapy, and in some instances surgical resection. Many do not have specific imaging characteristics that will enable the neuroradiologist to discriminate tumor recurrence from the inflammatory or necrotic changes that can result from treatment with radiation. 28 Both recurrent tumors and radiation injury typically demonstrate enhancement with gadolinium. Specific spectroscopic changes that occur with radiation-induced necrosis have been reported and include slight depression of NAA and variable changes in choline. 29-32 A recent study reported a 93% success rate in differentiating recurrent tumor from radiation injury with significantly increased Cho/NAA and Cho/Cr ratios (P < 0.001) in areas of recurrent tumor compared to areas of radiation injury and compared to normal adjacent brain tissue. 33 These results also are supported by previous work utilizing SVS, where the authors claim that a Cho/Cr ratio over 1.79 or lipid-lactate/Cho ratio less than 0.75 has a sevenfold increased odds of indicating tumor compared to pure necrosis.