Brain Metastases: Likelihood Ratios

Introduction: Often patients with a known primary cancer need to be staged to evaluate for brain metastases. This may occur in patients with neurological symptoms or those with cancers with high propensity for metastatic disease in the brain (e.g. lung cancer).

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Tags: Neoplasm Neurologic Tag this Diagnosis.

The likelihood ratios of findings for Brain Metastases are listed below. See the left navigation bar to change the display.

Pre-Test Probability (Prevalence): %.	Post-Test Probability (Predictive Value): %.	Switch to display mode.
Note that calculating probabilities from more than one** finding is inherently inaccurate because findings are not independent. (For example, using two positive findings that share a common pathogenesis is likely to overestimate the true probability.)

Good Positive Likelihood Ratio
Finding	Result	+LR	-LR
[ + ] PET/CT scan	+ 0 -	11.4	0.7
versus MRI in patients with lung cancer Study: Nuklearmedizin. 2011;50(3):101-6. PMID: 21165538

Poorly Diagnostic Findings
Finding	Result	+LR	-LR
[ + ] Contrast-enhanced Head CT		Sensitivity = 60%
versus CE-MRI. Per lesion . Very old data. Another study found sensitivity of 69% for detecting additional lesions in patients with one lesion seen on CT. Study: AJNR Am J Neuroradiol. 1991 Mar-Apr;12(2):293-300. PMID: 1902031 J Neurooncol. 1999;44(3):275-81. PMID: 10720207
[ + ] Non-contrast MRI		Sensitivity = 50.8%
per lesion, versus CE-MRI. Very old data in obsolete scanners, unclear how relevant this is to today. Study: AJNR Am J Neuroradiol. 1991 Mar-Apr;12(2):293-300. PMID: 1902031