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Biomedical subjects

T Rand

Publications and source records attributed to T Rand.

68 records · Page 4Linked to original sources
PubMed1994

[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.

Blood Glucose↗
PubMed1994

[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.

Absorptiometry, Photon↗
PubMed1994

[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.

Adolescent↗
PubMed1994

[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.

Adolescent↗
PubMed1994

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.

Brain↗
PubMed1993

[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.

Clostridium Infections↗
PubMed1991

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.

Aged↗
PubMedDate not supplied

PTA versus carbofilm-coated stents in infrapopliteal arteries: pilot study.

PURPOSE: To determine the primary success and short-term patency of stent application as a primary treatment modality for high-grade lesions of the infrapopliteal arteries compared with treatment with percutaneous transluminal angioplasty (PTA) in critical limb ischemia in a randomized prospective study. METHODS: Endovascular therapy was performed on 95 lesions in 51 patients (mean age 72.0 years, range 47-80 years) who presented clinically with Fontaine stages III and IV. One patient underwent treatment in both limbs. After angiographic lesion identification, patients were randomized for treatment by PTA (53 lesions in 27 patients) or stent application (42 lesions in 24 patients). Follow-up by clinical investigation and conventional angiography or spiral CT angiography was performed in 37 patients (57 lesions) 6 to 12 months after the procedure, or when clinically indicated. Evaluation was performed by two observers, double-blinded, with thresholds for lesion restenosis of 50% and 70%. Statistical evaluation was performed on a lesion basis by Kaplan-Meier estimated probability rates, and log-rank and Wilcoxon tests. The primary endpoint was the angiographic patency rate of treated lesions. RESULTS: The inter-reader agreement was high (kappa = 0.82). For the stent group the cumulative primary patency at 6 months was 83.7% at the 70% restenosis threshold, and 79.7% at the 50% restenosis threshold. For PTA, the primary patency at 6 months was 61.1% at the 70% restenosis threshold and 45.6% at the 50% restenosis threshold. Both results were statistically significant (p < 0.05). CONCLUSION: Infrapopliteal stent application is an effective treatment modality for high-grade lesions in chronic critical limb ischemia. Compared with PTA, higher patency rates can be expected after 6 months.

Aged↗
PubMedDate not supplied

Imaging articular cartilage defects with 3D fat-suppressed echo planar imaging: comparison with conventional 3D fat-suppressed gradient echo sequence and correlation with histology.

PURPOSE: Our goal was to shorten examination time in articular cartilage imaging by use of a recently developed 3D multishot echo planar imaging (EPI) sequence with fat suppression (FS). We performed comparisons with 3D FS GE sequence using histology as the standard of reference. METHOD: Twenty patients with severe gonarthrosis who were scheduled for total knee replacement underwent MRI prior to surgery. Hyaline cartilage was imaged with a 3D FS EPI and a 3D FS GE sequence. Signal intensities of articular structures were measured, and contrast-to-noise (C/N) ratios were calculated. Each knee was subdivided into 10 cartilage surfaces. From a total of 188 (3D EPI sequence) and 198 (3D GE sequence) cartilage surfaces, 73 and 79 histologic specimens could be obtained and analyzed. MR grading of cartilage lesions on both sequences was based on a five grade classification scheme and compared with histologic grading. RESULTS: The 3D FS EPI sequence provided a high C/N ratio between cartilage and subchondral bone similar to that of the 3D FS GE sequence. The C/N ratio between cartilage and effusion was significantly lower on the 3D EPI sequence due to higher signal intensity of fluid. MR grading of cartilage abnormalities using 3D FS EPI and 3D GE sequence correlated well with histologic grading. 3D FS EPI sequence agreed within one grade in 69 of 73 (94.5%) histologically proven cartilage lesions and 3D FS GE sequence agreed within one grade in 76 of 79 (96.2%) lesions. The gradings were identical in 38 of 73 (52.1%) and in 46 of 79 (58.3%) cases, respectively. The difference between the sensitivities was statistically not significant. CONCLUSION: The 3D FS EPI sequence is comparable with the 3D FS GE sequence in the noninvasive evaluation of advanced cartilage abnormalities but reduces scan time by a factor of 4.

Aged↗
PubMedDate not supplied

Condensing osteitis of the clavicle: MRI.

PURPOSE: Condensing osteitis of the clavicle is a rare benign disorder, seen exclusively in women and characterized by expansion and sclerosis of the medial end of the clavicle. The aim of this study was to evaluate the MR findings of this disorder. METHOD: MR images, obtained in four patients with evidence of condensing osteitis of the clavicle based on plain radiographs and clinical symptoms, included pre- and postcontrast T1 SE sequences, T2 SE images, GE images. RESULTS: MR images revealed consistent hypointense areas on T1-weighted SE images, corresponding to regions of clavicular sclerosis (n = 4). T2-weighted SE images showed signal characteristics ranging from low intermediate signal intensity in regions of sclerosis (n = 4). T2-weighted GE images revealed moderate to high signal intensity presumably related to bone marrow edema (n = 2). Contrast-enhanced T1-weighted SE images were characterized by mild to extensive intraosseous and periosseous enhancement of signal intensity (n = 2). CONCLUSION: MRI in cases of condensing osteitis of the clavicle reveals variable findings perhaps indicative of different stages of activity in this disease.

Adult↗
PubMedDate not supplied

Tibiofibular syndesmosis: high-resolution MRI using a local gradient coil.

PURPOSE: Our goal was to correlate high-resolution MR images of the tibiofibular syndesmosis with anatomic sections. METHOD: MRI was performed inside a local gradient coil on six cadaveric feet taped in 10-20 degrees dorsiflexion and 40-50 degrees plantar flexion by using axial and coronal T1-weighted SE sequences. After imaging, the specimens were frozen and sectioned into 3-mm-thick slices along the MR planes. Images were correlated with the anatomic sections. RESULTS: MRI depicted the anatomy of the tibiofibular syndesmosis and surrounding structures. With the foot taped in dorsiflexion, axial imaging provided optimum views of the anterior, posterior, interosseous, and transverse tibiofibular ligaments. Coronal images allowed visualization of the entire course of the anterior, posterior, and transverse tibiofibular ligaments. The multifascicular appearance of the anterior tibiofibular ligament was best visualized in coronal sections. With the foot taped in dorsiflexion or in plantar flexion, it was possible to distinguish the posterior tibiofibular ligament and transverse tibiofibular ligament from the posterior talofibular ligament in all specimens. CONCLUSION: High-resolution MRI using a local gradient coil provides excellent delineation of the ligaments of the distal tibiofibular syndesmosis.

Aged↗
PubMedDate not supplied

Intertarsal ligaments: high resolution MRI and anatomic correlation.

High resolution MRI was performed on four cadaveric foot specimens of human feet to demonstrate the ligaments of the tarsal joints. Spin echo T1 images were obtained using a local gradient coil that produces 6 G/cm and 100 A in all three axes. The best views for each of the individual ligaments were determined. High resolution MRI potentially can demonstrate most of the intertarsal ligaments.

Aged↗
PubMedDate not supplied

Collateral ligaments of the ankle: high-resolution MR imaging with a local gradient coil and anatomic correlation in cadavers.

Findings at high-resolution magnetic resonance (MR) imaging of the lateral and medial collateral ligaments of the ankle were compared with findings in anatomic sections from cadavers. MR imaging of six cadaveric feet was performed with a newly developed local gradient coil and axial and coronal T1-weighted spin-echo sequences. Axial imaging provided optimum views of the anterior and posterior talofibular ligaments, the deep layers of the medial collateral ligament, and the tibionavicular ligament. Coronal imaging allowed complete visualization of the calcaneofibular, posterior talofibular, tibiocalcaneal, and posterior tibiotalar ligaments. In both imaging planes, differentiation of the deep and superficial layers of the medial collateral ligament was possible. Differentiation between the syndesmotic complex and the lateral collateral ligament was accomplished easily; in particular, differentiation of the posterior tibiofibular ligament from the posterior talofibular ligament was not difficult because of the differing insertions of these ligaments. The inhomogeneous appearance of the medial collateral ligament and the posterior talofibular ligament on MR images correlated with areas of fatty tissue on corresponding microscopic sections. High-resolution MR imaging with a newly developed local gradient coil allows excellent visualization of the lateral and medial collateral ligaments of the ankle.

Adipose Tissue↗