Diagnosis of partial and total physeal arrest by bone single-photon emission computed tomography.

Bone single-photon emission computed tomography (SPECT), capable of creating maps of the distribution of osteoblastic activity in every spatial plane of a physis, should provide images of diagnostic value in the case of patients suffering from growth arrests (epiphysiodeses). Seventy-five bone SPECT scans were obtained in 64 children suspected to have developed physeal arrests. The transaxial slices of the physis, in the case of partial epiphysiodeses: (a) indicated the percentage of the remaining normal physis, (b) located the bony bridge within the physis and (c) showed the slowdown of the growth of the remaining normal physis induced by the bony bridge in some children. Misdiagnosis occurred in six patients. For total epiphysiodeses, the radionuclide diagnosis was confirmed in 20 of 21 patients. Radionuclide, x-ray and MRI examinations in the study of growth disturbances were found to be complementary.

Factor analysis of dynamic magnetic resonance imaging in predicting the response of osteosarcoma to chemotherapy.

RATIONALE AND OBJECTIVES: The response of osteosarcoma to preoperative chemotherapy was assessed using dynamic magnetic resonance imaging (MRI) processed by factor analysis of medical image sequences (FAMIS). METHODS: Forty-nine dynamic image sequences, acquired after a bolus injection of gadolinium in 10 patients, were processed by FAMIS: FAMIS is a means whereby physiologic contrast enhancement kinetics, called factors, and their spatial distribution, termed factor images, are estimated. Tumor volumes were measured on static MRIs, and factor images were compared with histologic maps of the resected specimens. RESULTS: A substantial increase in tumor volume reflected a poor response to chemotherapy. Viable tumor was precisely depicted by the early vascular factor image, reflecting rapid uptake by tumor vessels. This early uptake disappeared in all five patients who responded to chemotherapy, whereas it persisted in four of five nonresponders. CONCLUSION: FAMIS of dynamic MRI is proposed as a possible means of predicting the response of osteosarcoma to chemotherapy.

Pheochromocytoma in children: 15 cases.

Pheochromocytoma is an uncommon tumor in childhood; nevertheless, 20% of all pheochromocytomas are found in the pediatric population. Fifteen children have been treated in our institution from 1962 to 1990. One percent of patients referred over the same period for investigation of high blood pressure were found to have a pheochromocytoma. The majority of patients have hypertension. It varies in intensity and is paroxysmal in about half the patients. Many pediatric cases of unilateral, bilateral, extra-adrenal, familial, and recurrent pheochromocytomas have been reported. We reviewed our 28 years experience with this tumor and concentrated on the diagnosis, the preoperative and operative management, and the occurrence of the multiple endocrine neoplasia syndromes.

Desepiphysiodesis--elimination of partial premature epiphyseal closure. Experience of 17 cases.

Between 1975 and 1990, 17 growth plates have been operated on by epiphyseal bridge resection. The children were from 4 years and 10 months to 13 years and 10 months old. The etiology of partial closure was traumatic (10 times), caused by therapeutic mistakes (3 times), septic osteomyelitis (1 case), purpura fulminans (1 case), unknown (2 cases). There was always length discrepancy or deformity of bone. The regions that have been subjected to treatment were distal femur, proximal tibia, distal tibia, distal radius. Evaluation of the bone bridge was made by tomoscintigraphies and recently by MR imaging and computed tomoscintigraphy. The bone bridge size was from 2.5% to 60% of the growth plate surface; surgical technique consists of resection of bone bridge connecting epiphysis and metaphysis which is replaced by methyl metacrylate. In 16 cases simultaneous corrective osteotomy was performed. Results are poor, there were only two good results and 8 failures; seven results were medium. The failures can all be explained by mistakes in technique or indication, except one. Indications are post-traumatic narrow bridges in young children. It would be useful to know the vitality of the residual growth plate.

Activation of human primary visual cortex during visual recall: a magnetic resonance imaging study.

The degree to which the process involved in visual perception and visual imagery share a common neuroanatomical substrate is unclear. Physiological evidence for localization of visual imagery early in the visual pathways would have important bearing on current theories of visual processing. A magnetic resonance imaging technique sensitive to regional changes in blood oxygenation was used to obtain functional activation maps in the human visual cortex. During recall of a visual stimulus, focal increases in signal related to changes in blood flow were detected in V1 and V2 cortex in five of seven subjects. These experiments show that the same areas of the early visual cortex that are excited by visual stimulation are also activated during mental representation of the same stimulus. Some of the processes used in topographically mapped cortical areas during visual perception may also be utilized during visual recall.

Computed tomography with normal chest radiograph in tuberculous infection.

Children with primary tuberculosis infection without disease must be identified and treated preventively to avoid an increase in the incidence of tuberculosis in children. However, the recognition of infected cases without disease is often difficult. In particular, minimal active disease may be present in many cases but unrecognised on chest radiography. Computed tomography was therefore performed in 15 children with tuberculous infection and a normal chest radiograph to measure the size of their mediastinal lymph nodes. Ten control children without tuberculosis were also evaluated. When compared with controls it was found that nine of 15 (60%) infected children had enlarged lymph nodes. Adenopathies were more frequent in infected children less than 4 years old than in those over 8 years old. The demonstration of unrecognised active disease in many infected children raises the question of the adequate treatment for these children. It is proposed that a two drug regimen would be more appropriate than isoniazid alone in these cases.

Gadolinium-DOTA enhanced MRI of painful osseous crises in children with sickle cell anemia.

In order to evaluate the role of gadolinium-DOTA enhanced MRI in the management of painful osseous crises in children with sickle cell anemia (SCA), nine children with SCA underwent MRI, bone scans and ultrasonographic studies during 11 osseous crises. Imaging findings were compared with the final diagnosis: three acute osteomyelitis (AO) and 16 acute infarcts (AI). MRI could not differentiate AO from AI. The appearance of severe AI was very misleading and was similar to the usual appearance of AO, including soft tissue changes, periosteal reaction and patterns of enhancement. Gadolinium-DOTA enhanced MRI was useful for determining the anatomic site and extent of AO or AI and for distinguishing between necrotic material, fluid collection and vascularized inflammatory tissue. It can also help to guide the aspiration of intraosseous, subperiosteal and soft tissue fluid collections.

Juvenile rheumatoid arthritis of the knee: MR evaluation with Gd-DOTA.

Synovial hypertrophy, effusion, and articular cartilage status were evaluated with gadolinium tetraazacyclododecanetetraacetic acid (DOTA)-enhanced magnetic resonance (MR) imaging in 24 knees in 24 pediatric patients (17 female, seven male; mean age, 10 years; range, 3-18 years) with juvenile rheumatoid arthritis (JRA). T1-weighted spin-echo sequences were performed with a 0.5-T unit before and immediately after injection of Gd-DOTA (0.1 mmol/kg). Substantial enhancement of synovial proliferation was seen in 23 of 24 knees, allowing precise assessment of pannus extension (n = 23), joint effusion (n = 21), cartilage loss (n = 21), and meniscal hypotrophy (n = 23). On T1-weighted images without contrast enhancement, cartilage thickness, loculation of joint effusion, and pannus extension were underestimated. Thus, Gd-DOTA-enhanced MR imaging is mandatory in the assessment of knee involvement in children with JRA and may prove to be useful in the evaluation of response to therapy.