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Loss of bone and muscle mass are major findings of male hypogonadism. In order to determine the long-term effect of testosterone replacement therapy on spinal bone and muscles, the trabecular and cortical bone mineral density, vertebral body area and paraspinal muscle area were assessed by quantitative computed tomography in 32 testosterone-substituted patients, aged 18-74 years, with idiopathic hypogonadotropic hypogonadism (n = 6), pituitary insufficiency (n = 5), Klinefelter syndrome (n = 12) or other forms of primary hypogonadism (n = 9). They were followed for a mean period of 3.2Ϯ1.7 years (meanϮS.D.), ranging from 1 to 7 years. A significant correlation between initial serum testosterone levels and bone mineral density was found in patients with congenital forms (r = 0.58; P<0.05) but not in those with acquired forms. A significant increase in trabecular and cortical bone mineral density (P<0.001) was documented in the course of replacement therapy in all patients regardless of the type of hypogonadism and age of patients. A slight but significant increase in paraspinal muscle area was observed if all patients were taken together (P<0.01). The area of paraspinal muscle correlated with body weight (r = 0.58; P<0.001) and moderately with trabecular bone mineral density (r = 0.4; P<0.01). Its increase did not correspond to the change observed for trabecular and cortical bone mineral density. Vertebral body area did not change over time. It correlated only with height and weight but not with bone mineral density. In conclusion, testosterone therapy of hypogonadal men improves both trabecular and cortical bone mineral density of the spine independently of age and type of hypogonadism while vertebral area remains unchanged. The effects seen on paraspinal muscles emphasize the clinical benefit of adequate replacement therapy for the physical fitness of hypogonadal men.

Summary:Our aim was to quantify irradiation-induced permeability alterations of the blood-bone marrow barrier (BMB) with dynamic contrast enhanced magnetic resonance imaging (MRI). The standard small molecular contrast agent, gadoterate meglumine, and a new macromolecular contrast agent, carboxymethyldextran-Gd-DOTA (CMD-Gd-DOTA), were compared. Twenty New Zealand white rabbits underwent MRI of the bone marrow before and 1-2 days after total body irradiation (TBI). Dynamic, repetitive T1-weighted MRI was performed before and after injection of either 0.05 mmol/kg BW CMD-Gd-DOTA (n = 10) or 0.5 mmol/kg BW gadoterate (n = 10). Bone marrow contrast enhancement was quantified as delta signal intensity: ⌬SI = ͉(SI post − SI pre ) / SI pre ͉ * 100%. All MRI data were compared with the histopathologic BMB ultrastructure. Dynamic bone marrow ⌬SI data steadily increased after CMD-Gd-DOTA injection, while blood ⌬SI data slightly decreased. This bone marrow contrast enhancement, indicative of contrast agent extravasation, was significantly higher and prolonged in the irradiated group as compared to non-irradiated controls (P Ͻ 0.05) and corresponded to irradiation-induced alterations of the BMB ultrastructure seen on electron microscopy. By contrast, ⌬SI data of non-irradiated and irradiated marrow were not significantly different following gadoterate injection (P Ͼ 0.05). We conclude that irradiation-induced alterations in BMB permeability could be reliably assessed with dynamic MRI, using the new macromolecular contrast agent CMD-Gd-DOTA. Bone Marrow Transplantation (2000) 25, 71-78.

The aim was to compare the diagnostic performance of dynamic Gd-DTPA- and ferumoxides-enhanced MRI for hepatocellular carcinoma (HCC). Twenty-five patients with chronic hepatitis or liver cirrhosis underwent both dynamic gadopentetate- and ferumoxides-enhanced MRI studies of the liver for HCC detection on the same day. MR data of both studies were retrospectively and independently analyzed. Two observers determined in consensus the grade of diffuse fibrotic liver changes (mild, moderate or severe) and the number of focal lesions. HCCs were confirmed by histology (n=22) and/or follow-up studies for at least six months (n=64). Differences in results obtained from both MR data sets were tested for significance with the McNemar's test (p<0.05). Ferumoxides-enhanced MR images detected 84 of 99 hepatic lesions, including 82 of 86 HCCs and 2 false positive, nonmalignant lesions, while Gd-DTPA-enhanced MR images detected 92 of 99 hepatic lesions, including 81 of 86 HCCs and 11 false positive, nonmalignant lesions. Sensitivity of MRI for detection of HCCs was not significantly different between ferumoxides-enhanced (95.3%; p>0.05) and Gd-DTPA-enhanced scans (94.2%). Gd-DTPA- and ferumoxides-enhanced MRI perform equally well for HCC detection. The majority of small hypervascular hepatic lesions, detected on dynamic Gd-DTPA-enhanced MRI but not on ferumoxides-enhanced MRI, represent no HCCs.

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