[Evidence of fluoride-induced effects on the calcaneus by measurements of broadband ultrasound attenuation (BUA)]

We measured broadband ultrasound attenuation (BUA) of the calcaneus as well as radial (RBD) and spinal bone density (SBD) in normal and osteoporotic females (n = 188) both before treatment and after long-term fluoride therapy. RBD was measured using single photon absorptiometry of the non-dominant distal forearm (SPA) and spinal bone density (SBD) was assessed using quantitative CT (QCT). In untreated osteoporotic patients (n = 62), BUA as well as the other densitometric methods showed significantly lower values (p < 0.05) when compared to age matched controls (n = 75). Females with osteoporosis and long-term treatment with fluoride (n = 51) had both significantly higher BUA values and higher spinal bone density when compared to women with untreated osteoporosis. BUA and SBD were correlated in the entire group (r = 0.5, r < 0.0001) as well as in the subgroups of untreated (r = 0.48, p < 0.001) and fluoride-treated patients with osteoporosis (r = 0.4, p < 0.05). These results suggest that BUA provides further evidence of an osteogenic response to fluoride at peripheral weight-bearing skeletal sites such as the calcaneus.

[Basics of MRI technique and MRI image interpretation]

Today magnetic resonance imaging (MRI) is an important routine diagnostic tool in orthopaedics. It is based on the nuclear magnetic resonance phenomenon: "free" hydrogen atoms (mainly from water) become field-parallel in a strong outer magnetic field. They reach a higher energy level by application of an additional electromagnetic field. After shutdown of this outer field the atoms send out electromagnetic waves (radiowaves), representing the MR signal. Different amounts of "free" water result in various image characteristics. Typically, a higher tissue water content is represented by high MR signals, e.g. in blastomas, inflammations and degenerative changes. Waterless structures such as calcified or fibrous tissues, tendons and ligaments show low MR signals. Fatty structures have high signals; proteins dissolved in "free" water change the water signal dramatically. Besides these basic parameters, para-, ferro- and super-paramagnetic materials--ether naturally present in the human body, such as methemoglobin, or artificially introduced, such as MR contrast media--and flow are responsible for different grey shades in MRI. MRI is not associated with ionizing radiation and allows imaging in all planes without changing the patient's position. Disadvantages of MRI are high costs and low availability. Future technical developments will result in shorter imaging times and broadening of the application spectrum, leading towards "MR fluoroscopy" and MR interventions.

[Bone inflammation (including spondylitis)]

MRI diagnosis of bony inflammations has sensitivity of up to 96%, but specificity of only 70-87%. The most common reasons for false-positive results are fractures, infarctions, neoplasms, septic arthritis and aggressive metastasis. Early MRI diagnosis is based on bone marrow oedema, which is hypointense on T1-weighted images, hyperintense on T2-weighted images. Reactive fibrovascular tissue and hyperaemia lead to contrast enhancement. Necrosis, calcification and sequestra show low signal intensities. Increasing calcifications and restructuring of spongiosa are not well visualized in MRI. In spondylitis, fat conversion is a good marker for healing. Complications of osteomyelitis (e.g. soft tissue abscesses) can be diagnosed by MRI with high sensitivity. In the primary diagnosis and follow-up of osteomyelitis (spondylitis), standard X-ray exams should be performed first. In the initial studies MRI can replace bone scintigraphy, which has poor morphological resolution. Semiquantitative follow-up studies can be done by MRI or scintigraphy.

[Recurrent renal vein thrombosis in a premature infant. Doppler ultrasound diagnosis and follow-up]

Renal vein thrombosis (RVT) is a rare disorder in neonates. Early diagnosis is mandatory since immediate thrombolytic therapy favours prognosis. Our case report describes RVT demonstrated by Duplex Doppler Ultrasound. A possibly characteristic sequence of changes in the echogenicity of the renal parenchyma and in the Duplex Doppler flow pattern of the renal arteries could be found.

[Ultrasound monitoring of the umbilical artery catheter. A case of a newborn infant with recurrent hypoglycemia]

Hypoglycaemia in neonates can be caused by malposition of the umbilical artery catheter (UAC). If the tip of the umbilical arterial catheter is located next to the origin of the great abdominal vessels glucose infusion is mainly directed into the coeliac trunk and superior mesenteric artery. Direct stimulation of the pancreatic gland might then result in hyperinsulinaemic hypoglycaemia. Generally, UAC position is controlled by x-ray. When using ultrasound for location of the UAC the exact topography and especially the relation of the tip of the UAC to the great vessel lumina can be documented precisely.

MR assessment of brain maturation: comparison of sequences

PURPOSE

To evaluate the role of short-inversion-time inversion-recovery (STIR) sequences in assessment of brain maturation.

METHODS

Twenty-seven infants and young children with normal neurologic development were examined by 1.5-T MR using a circularly polarized head coil. Axial T1-weighted and T2-weighted and spin-echo and STIR images were obtained. Signal intensity of different anatomic structures at individual sequences was classified relatively to reference sites and temporal sequence of signal intensity was observed.

RESULTS

Signal intensity changes on T1-weighted and T2-weighted spin-echo sequences occurred at ages described in various previous publications. On STIR images intensity changes became apparent at a time between T1-weighted and T2-weighted images. The advantages of the STIR sequence were improved assessment of myelination of subcortical cerebral white matter from 6 to 14 months and good contrast between white matter lesions and cerebrospinal fluid.

CONCLUSION

Our results suggest that from 0 to 6 months myelination can be assessed best using a combination of T1-weighted and T2-weighted images; from 6 to 14 months a combination of T2-weighted and STIR images seems to be advantageous; after 14 months the use of only T2-weighted sequences is sufficient. After 14 months STIR images may be useful in detecting small periventricular white matter lesions or in cases with retarded myelination and isointensity between gray matter and white matter.

Sonographic detection of internal jugular vein thrombosis after central venous catheterization in the newborn period

We sonographically investigated the internal jugular veins of 40 children who had undergone catheterization of the vein (group A: silastic catheter, n = 24; group B: polyurethane catheter, n = 16) in the neonatal period. The average age at catheter implantation was 43 +/- 73 days, the average birthweight 2414 +/- 1145 g, and the average gestational age 34.8 +/- 5.0 weeks. We performed follow-up longitudinal and transverse high resolution sonographic scans including routine examination of the contralateral jugular vein at a mean age of 3.7 +/- 1.5 years. In group A thrombotic alterations were detected in 8 aut of 24 patients. In three of these patients we found mild clinical symptoms. In group B thrombotic alterations were detected in 1 aut of 16 patients without clinical symptoms. Mean birthweight (1815 versus 3313 g) and mean gestational age (32.3 versus 38 weeks) were significantly lower and indwelling time of the catheters (18 versus 11 days) was significantly longer in group A. Our results indicate that jugular vein thrombosis is a frequent long-term complication in neonates after jugular vein catheterization. High resolution ultrasonography is an adequate method for detecting jugular vein thrombosis and should therefore routinely be performed for long-term follow-up.

[Generalized clostridial infection in a 60-year-old patient with massive soft tissue emphysema on thoracic radiography]

We report a case of a 60-year-old patient with progressive soft tissue emphysema caused by infection with clostridium septicum. In contrast to a rather linear spread of air in non infectious soft tissue-emphysema, in this case a mainly vesicular spread of air in the soft tissue is noted on plain films. Together with the clinical history, this finding may indicate an infectious cause. The radiological interpretation is an important step in the diagnostical workup.

Alzheimer disease: measuring loss of cerebral gray matter with MR imaging

The distributions of the cerebral gray matter, the white matter, and the intracranial cerebrospinal fluid (CSF) were measured in 14 patients with Alzheimer disease (AD) and in 14 healthy control subjects. The measurements, derived from two specifically designed magnetic resonance inversion-recovery sequences, compensate for partial signal averaging. The percentage of the gray matter in the brains of AD patients (44.9% +/- 4.4) was significantly lower than in control subjects (50.2% +/- 3.2). The most significant reduction (P less than .001) occurred in the temporal lobes (13.8%) and a central region (12.8); the reduction in frontal lobe (11.2%) and occipital lobe (9.2%) was also statistically significant (P less than .01). There was an increase in the CSF volume in the temporal, occipital, and frontal regions; no region showed a significant difference in the white matter content. The findings of diffuse changes and temporal lobe involvement in AD are consistent with pathologic observations of cortical cell loss.