To evaluate extent of bone marrow involvement and disease severity in Gaucher patients, results of modified Dixon quantitative chemical shift imaging (QCSI) of the lumbar spine were correlated with quantitative analysis of marrow triglycerides and glucocerebrosides and with quantitative determination of splenic volume at magnetic resonance (MR) imaging. High-field-strength MR spectra of surgical marrow specimens were dominated by a single fat and a water peak, validating use of QCSI. QCSI showed average vertebral marrow fat fractions of 10% +/- 8 in Gaucher patients (normal adult averages, 29% +/- 6). Relaxation times for lipid and water approximated normal averages; bulk T1 values were significantly longer, reflecting decreased marrow fat. Glucocerebroside concentrations were higher in Gaucher marrow and inversely correlated with triglyceride concentrations. Extent of marrow infiltration determined by fat fraction measurements correlated with disease severity measured by splenic enlargement. These results show that as Gaucher cells infiltrate bone marrow and displace normal marrow adipocytes, bulk T1 increases due to the higher T1 of water compared with that of fat. QCSI provides a sensitive, noninvasive technique for evaluating bone marrow involvement in Gaucher disease.
A modified Dixon chemical shift imaging technique was used to quantify longitudinal changes in bone marrow that occur during induction chemotherapy in patients with acute leukemia. Results were correlated with those of bone marrow biopsy. Forty-seven quantitative images were obtained with a 0.6-T whole body imager in a total of 11 patients over the course of treatment. Quantitative measures of fat fractions and water and fat component T1 and T2 relaxation times were determined, as well as average relaxation times. Imaging results showed sequential increases in fat fractions among responding patients (n = 9), consistent with biopsy-confirmed clinical remission. In the two patients who later relapsed, sharp decreases in fat fractions were noted. In the two patients who failed to regenerate normal marrow, unchanging, low fat fractions were seen. Water component T1 values reflected posttherapeutic changes in the hematopoietic elements. Quantitative chemical shift imaging proved useful in assessing treatment response in acute leukemia during early bone marrow regeneration and, later, in ascertaining remission or relapse.
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