H-1 MR SPECTROSCOPY DETECTION OF LIPIDS AND LACTATE IN METASTATIC BRAIN-TUMORS

H-1 MR spectroscopy was used to correlate the metabolite-signals in 66 untreated metastatic brain tumors with the results of Gd-DTPA enhance d MRI, Cubic volumes containing brain metastases of lung cancer (n=17) , mammary carcinoma (n=24), melanoma (n=12) and those originating from other tumors (n=13) were examined using the double spin echo techniqu e with CHESS pulses for water suppression and TE=135 ms, Apart from tr ends toward reduced signals of choline-containing compounds (Cho) and reduced post-Gd MRI contrast in lung cancer compared with the other pa thology groups, the four tumor groups had similar MRI and MRS characte ristics. Metastases without lipid or lactate (Lact) signal in the H-1 MR spectra were comparatively small in size with homogeneous post-Gd M RI enhancement (33+/-5%, means+/-SEM; n=24) and elevated Cho signals c ompared with normal contralateral brain tissue (70+/-5% of contralater al N-acetyl aspartate signal; p<0.001), The other metastases showed ei ther unambiguous lipid signals (n=30) or MRS detectable Lact (n=12) an d were heterogeneous on MRI with divergent signals of Gd-enhancement ( 49+/-5% vs 14+/-8%, p<0.001) and Cho (88+/-10 vs 47+/-8% of contralate ral NAA; p=0.02), Those with Lact were significantly larger compared w ith both other groups (p<0.02, both). It is concluded that brain metas tases can be categorized into early stage (Cho), intermediate stage (l ipid, higher Cho) and late stage metastases (Lact, lower Cho).