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Biomedical subjects

D Jaramillo

Publications and source records attributed to D Jaramillo.

At least 37 records · Page 2Linked to original sources

Developing epiphysis: MR imaging characteristics and histologic correlation in the newborn lamb.

PURPOSE: To correlate magnetic resonance (MR) signal characteristics of developing regions at the ends of bones with the histologic findings. MATERIALS AND METHODS: In 36 newborn lamb epiphyses (including cartilage of the epiphysis and physis, and bone of the secondary ossification center and juxtaphyseal metaphysis), signal intensity and thickness of cartilaginous regions seen on MR images were correlated with architecture and thickness of zones shown in corresponding histologic sections. Possible effects of T2, magnetization transfer, fat or water content, chemical shift, and anisotropy on differences in regional signal intensity were evaluated. RESULTS: MR imaging depicted five regions between the secondary ossification center and the metaphysis corresponding histologically to (a) zone of provisional calcification of the secondary ossification center, (b) physis of the secondary ossification center, (c) epiphyseal cartilage, (d) physis, and (e) zone of provisional calcification. The thickness of regions shown on T1- and T2-weighted images correlated with that of histologic zones (r = .9). T2 signal intensity and relaxation time were greater in physeal than in epiphyseal cartilage (P < .01). No regional differences due to fat or water content, magnetization transfer, chemical shift, or anisotropy were found. CONCLUSION: MR imaging findings differentiate epiphyseal and physeal regions and correlate with histologic findings. T2 is slower in physeal than in epiphyseal cartilage, probably reflecting differences in water binding.

Animals↗

Glenohumeral deformity secondary to brachial plexus birth palsy.

Ninety-four patients who had brachial plexus birth palsy were entered into a prospective study to evaluate the association between persistent palsy, age-related musculoskeletal deformity, and functional limitations. Of these patients, forty-two had either computerized tomography or magnetic resonance imaging to assess the presence and degree of incongruity of the glenohumeral joint, deformity of the humeral head, and hypoplasia of the glenoid as part of the preoperative planning for a reconstructive operation. Functional ability was rated with use of the classification of Mallet, on a scale of 1 to 5. The mean glenoscapular angle (the degree of retroversion of the glenoid) on the affected side was -25.7 degrees compared with -5.5 degrees on the unaffected side. Twenty-six (62 per cent) of the forty-two shoulders had evidence of posterior subluxation of the humeral head, with a mean of only 25 per cent (range, 0 to 50 per cent) of the head being intersected by the scapular line. Progressive deformity was found with increasing age (p < 0.001). The natural history of untreated brachial plexus birth palsy with residual weakness is progressive glenohumeral deformity due to persistent muscle imbalance. The status of the glenohumeral joint must be addressed when the choice between tendon transfer and humeral derotation osteotomy for reconstruction of the shoulder is considered for these patients.

Adolescent↗

Gadolinium-enhanced MR imaging of pediatric patients after reduction of dysplastic hips: assessment of femoral head position, factors impeding reduction, and femoral head ischemia.

OBJECTIVE: We describe gadolinium-enhanced MR imaging of position and vascular enhancement of the femoral head in pediatric patients who have undergone reduction of hip dislocation. SUBJECTS AND METHODS: Within 24 hr of hip reduction and spica casting, we performed 25 gadolinium-enhanced MR studies in 18 infants and young children (15 girls, three boys) with 23 dysplastic hips. All but two patients underwent closed reductions. We evaluated intraoperative arthrograms for obstacles to reduction and subsequent radiographs for avascular necrosis. RESULTS: MR images showed that all femoral heads were in their respective acetabula, but several structures interfered with concentric reduction. Obstacles to reduction included a pulvinar (n = 16), infolding of the capsule (n = 9), interposition of the labrum (n = 2), and a hypertrophied ligamentum teres and transverse ligament (n = 2). All 50 femoral heads showed enhancement: 35 normally, 10 homogeneously but less than on the contralateral femoral head or the ipsilateral greater trochanter, and five with areas of focally decreased enhancement. Hips that showed decreased enhancement had undergone greater degrees of abduction (r = .38, p < .01). CONCLUSION: Gadolinium-enhanced MR imaging can reveal abnormalities of hip position and proximal femoral epiphyseal and physeal vascularity that can occur after hip reduction. Abnormalities of enhancement were more frequent in patients who had greater femoral abduction. The effect of decreased epiphyseal vascular enhancement is still uncertain.

Arthrography↗

Growth cartilage: normal appearance, variants and abnormalities.

The cartilaginous structures in the growing ends of the bone have a complex anatomy. MR imaging allows exquisite depiction of these structures. The normal anatomy and biochemical features of the zones of cartilage are reviewed. Based on an analysis of signal characteristics, it is possible to optimize the use of pulse sequences to study the normal structures and abnormalities of growing bone.

Adolescent↗

Musculoskeletal trauma in children.

MR imaging has facilitated the study of pediatric injuries by demonstrating the extraosseous and cartilaginous component of these lesions. In injuries to the epiphysis and physis, osteochondral injuries and avulsion injuries, the cartilaginous component is usually the most important part of the lesion. Stress fractures and other injuries to the marrow also can be demonstrated with MR imaging. In the context of musculoskeletal injuries in children, MR imaging is most valuable in demonstrating the extent of injuries to radiographically occult areas.

Adolescent↗

Local physeal widening on MR imaging: an incidental finding suggesting prior metaphyseal insult.

OBJECTIVE: To offer a descriptive review which characterizes and evaluates the significance of local physeal widening, (cartilaginous signal extending from the physis into the adjacent metaphysis), identified on magnetic resonance (MR) imaging. MATERIALS AND METHODS: MR images (recollected from exams performed between 1988 and 1995) of 31 metaphyses in 22 children where we recognized local physeal widening were examined retrospectively. These areas of physeal widening were evaluated for morphology, depth, location, signal intensity, and the coexistence of epiphyseal alterations. The characteristics of the signal abnormalities were correlated with the duration and type of any identifiable insult to the adjacent metaphysis, and with the development of growth disturbance. RESULTS: Twenty-six metaphyses had identifiable insults (19 single event and 7 sustained or repetitive). The widened physes were of focal tongue (n = 15), broad band (n = 10), or mixed (n = 6) morphology. Most (n = 27) areas of widening were isointense with the physeal cartilage on all sequences. Subsequent growth disturbance was more likely when the metaphyseal insult was a single event rather than sustained or repetitive (P = 0.023), with focal tongues (P = 0.029), and with centrally located lesions (P = 0.030). In five cases, the adjacent epiphysis showed signal abnormalities; all developed growth disturbance. Histologic examinations available in two limbs confirmed that the MR findings represented extensions of hypertrophic physeal chondrocytes into the metaphysis. CONCLUSION: Incidentally observed local physeal widening in a growing bone may represent the imprint of a previous or ongoing interference with endochondral ossification from a prior metaphyseal insult, rather than a primary metaphyseal disorder. Single event insults, physeal widening of focal tongue morphology, central distribution in the metaphysis, and concomitant epiphyseal signal abnormalities on MR imaging are significant predictors of subsequent growth disturbance.

Adolescent↗

MRI demonstration of occult purely chondral fractures of the tibia: a potential mimic of meniscal tears.

We report the case of a 12-year-old boy with bilateral, purely chondral fractures of the tibia. The patient had Crohn's disease treated with systemic corticosteroids. MR images of the knee were initially interpreted to show a bucket-handle tear of the lateral meniscus. However, arthroscopic evaluation revealed purely chondral fractures of the tibial plateau without meniscal damage. Re-evaluation of the MR study identified the chondral fracture of the lateral tibial articular cartilage detected arthroscopically. This purely chondral fracture of the tibial plateau represented a rare finding in the symptomatic knee that mimicked a meniscal tear by history, physical exam, and MR imaging.

Adrenal Cortex Hormones↗

In vivo bone marrow lipid characterization with line scan Carr-Purcell-Meiboom-Gill proton spectroscopic imaging.

Line scan Carr-Purcell-Meiboom-Gill spectroscopic imaging sequences have been used to extract lipid chemical composition indices in healthy adult bone marrow in the knee at 1.5 T. Since several spectroscopic echo readouts follow each excitation, the information acquired reflects a balance between spectral T2 decay processes and spectral resolution. To examine this balance in detail, data sets with two different echo spacings and spectral resolutions have been acquired to compare the information available from each in studies of bone marrow. Oils for which high field (7 T) proton spectra were recorded were used to evaluate the accuracy of lipid chemical composition indices extracted from the line scan Carr-Purcell-Meiboom-Gill spectroscopic imaging methods at 1.5 T. The extension of the method to fast spectroscopic imaging of bone marrow with multiple echoes is demonstrated.

Adult↗

Methotrexate osteopathy in patients with osteosarcoma.

PURPOSE: To determine the frequency of osteopathy in patients treated with high-dose, short-term, intravenous methotrexate for osteosarcoma and whether this complication varies with patient age and methotrexate dose. MATERIALS AND METHODS: Radiographs and available scintigrams of 87 patients with osteosarcoma who received high-dose methotrexate were reviewed retrospectively for severe osteopenia, dense zones of provisional calcification, insufficiency fractures, and involvement of multiple bones. At least three of these radiographic abnormalities were required for the diagnosis of osteopathy. Patients with bone metastases were excluded. RESULTS: Eight patients (cumulative dose, 60-144 g/m2) exhibited adverse skeletal findings similar to those described in children with leukemia who received low-dose maintenance methotrexate. Images showed severe osteopenia (n = 8), dense zones of provisional calcification (n = 8), multiple bone involvement (n = 6), and insufficiency fractures (n = 6). Most commonly affected sites were the distal tibia (n = 7), distal radius and proximal humerus (n = 3), and calcaneus and public ramus (n = 2). The affected patients were significantly younger (mean age, 9.2 years; P < .001) than the 79 unaffected patients (mean age, 14.9 years). CONCLUSION: Osteopathy occurs in approximately 9% of children who receive high-dose methotrexate for osteosarcoma and is substantially more likely to occur in younger patients. The complication rate was not directly dose dependent.

Adolescent↗

Normal gadolinium-enhanced MR images of the developing appendicular skeleton: Part I. Cartilaginous epiphysis and physis.

OBJECTIVE: We have used gadolinium-enhanced MR imaging to define the expected normal appearance of the developing cartilaginous epiphyses and physes in neonates, infants, and children and to define the changes with maturity in epiphyseal vascular pattern. MATERIALS AND METHODS: We analyzed gadolinium-enhanced MR images of 80 normal epiphyses in 48 neonates, infants, and children who were 1 month to 15.5 years old. We studied the differences in enhancement ratios for the epiphyses and physes and the epiphyseal vascular pattern at various development stages. We correlated the MR imaging findings with histologic and injection studies of immature epiphyses. RESULTS: Gadolinium enhancement allowed differentiation between physeal and epiphyseal cartilage and revealed epiphyseal vascular canals. Enhancement proved to be greater in the physeal than in the epiphyseal cartilage (p < .001). In the unossified epiphysis, the vascular canals were mainly parallel. After the development of the secondary ossification center, these canals came to have a radial pattern (p < .0001). Comparison with cadaveric specimens confirmed how, with age, the arrangement of these canals changed. Also, physeal enhancement decreased with physeal closure. CONCLUSION: Gadolinium-enhanced MR imaging reveals differential enhancement of the physis, epiphyseal vascular canals, and epiphyseal cartilage. The pattern of epiphyseal vessels and degree of enhancement of the physis change with maturity.

Adolescent↗

Normal gadolinium-enhanced MR images of the developing appendicular skeleton: Part 2. Epiphyseal and metaphyseal marrow.

OBJECTIVE: We have studied how gadolinium enhancement of T1-weighted MR images affects the expected normal differences in signal intensity between metaphyseal hematopoietic and epiphyseal fatty marrow. We have also analyzed how enhancement affects the expected normal changes in the MR images of the marrow due to fatty conversion. MATERIALS AND METHODS: We analyzed gadolinium-enhanced MR images of normal distal femurs in 18 immature rabbits that were 5-11 weeks old and of normal proximal femurs in 18 infants, children, and young adults who were 2 months to 21 years old. In all subjects, we studied the change with age in signal intensity and enhancement ratio of the epiphyseal and metaphyseal marrow. In the rabbits, marrow composition and transformation were histologically verified. RESULTS: On unenhanced T1-weighted MR images of the rabbits and of the infants, children, and young adults, epiphyseal signal intensity always exceeded metaphyseal signal intensity; however, the enhancement ratio was always greater in the metaphysis. The signal intensity in metaphyseal and epiphyseal marrow on unenhanced MR images increased with age. However, enhancement ratios decreased with age in both areas. In the rabbits, histologic studies showed more fatty marrow in the epiphysis than in the corresponding metaphysis and an age-related increase in marrow fat at both sites. CONCLUSION: In the marrow of the extremities, gadolinium enhancement is greater in the (hematopoietic) metaphysis than in the (fatty) epiphysis. In both areas, enhancement decreases as the marrow becomes more fatty. On T1-weighted images, administration of a gadolinium-containing contrast agent reduces the normal contrast between hematopoietic and fatty marrow and obscures the changes in marrow signal intensity due to fatty conversion.

Adolescent↗

MR imaging of the normal developmental anatomy of the elbow.

Growth and ossification of the elbow are complex. Interpreting MR images of the elbow in children requires a knowledge of the elbow's developmental changes. This article discusses the basic principles of growth and development of the distal humerus, proximal radius, and ulna. The signal characteristics of cartilage and marrow in the immature skeleton are described. Technical factors related to imaging of growth cartilage are outlined, and specific challenges during imaging of the pediatric elbow are emphasized. The changing MR appearance of the elbow due to ossification and physeal closure is described. The article also explains several pitfalls encountered.

Bone Development↗

Musculoskeletal magnetic resonance imaging: how we do it.

This paper reviews the techniques that we employ to perform musculoskeletal magnetic resonance imaging in the pediatric patient. We examine the procedures for preparation and screening of the patient and the protocols for sedation. The selection of imaging coils and sequences for the evaluation of the pediatric musculoskeletal system is also addressed, followed by a summary of scanning protocols.

Bone Diseases↗

Thallium-201 uptake in Langerhans cell histiocytosis of bone.

A case in which there was thallium-201 (201Tl) uptake in Langerhans cell histiocytosis (LCH) of the left femoral diaphysis is presented. The authors propose that 201Tl scintigraphy is potentially useful in the diagnosis and follow-up of patients with LCH.

Bone Diseases↗

MR imaging in congenital lower limb deformities.

Treatment for children with congenital deformities of the lower extremities may vary, depending on the state of the unossified skeletal structures and surrounding soft tissues. The purpose of our study was to demonstrate the spectrum of the osteochondral and extrasosseous abnormalities as depicted with MR imaging. We retrospectively reviewed MR examinations of 13 limbs of ten children (aged 1 month-9 years, mean 2.1 years) with longitudinal and transverse deformities of the lower extremities. The lesions imaged were fibular hemimelia (n = 5), tibial hemimelia (n = 5), and congenital constriction bands (n = 3). Each examination was assessed for abnormalities in the osteocartilaginous and extraosseous (articular or periarticular components such as ligaments, tendons, and menisci; the muscles and the arteries) structures. Abnormalities were seen in all patients. Osteocartilaginous abnormalities in the patients with longitudinal deformities included abnormal distal femoral epiphyses, abnormal proximal tibial physes, hypertrophied and dislocated proximal fibular epiphyses, unsuspected fibular and tibial remnants, and absence or coalition of the tarsal bones. No osteocartilaginous abnormalities were seen in the patients with congenital constriction bands. Articular abnormalities about the knee in patients with either form of hemimelia included absent cruciate ligaments and menisci, dislocated or absent cartilaginous patellae, absent patellar tendons, and abnormal collateral ligaments. All but one limb imaged had absent or attenuated muscle groups. Of the nine MR arteriograms performed at the level of the knee, eight were abnormal. The normal popliteal trifurcation was absent or in an abnormal location. We conclude that MR imaging of children with congenital lower extremity deformities shows many osteochondral and extraosseous abnormalities that are not depicted by conventional radiography. This information can help to plan early surgical intervention and prosthetic rehabilitation.

Child↗