Ultrafast MR imaging of the foetus: a study of 25 non-central nervous system anomalies.

PURPOSE: The aim of this paper is to suggest Magnetic Resonance (MR) Imaging as a useful tool in prenatal diagnosis. Although ultrasonography (US) is the imaging technique of choice for prenatal screening, in cases of complex malformations US findings may be sub-optimal and give rise to diagnostic difficulties requiring further investigation. Our study is focused on non-central nervous system (CNS) abnormalities of the foetus imaged using the ultrafast sequence EXPRESS. MATERIALS AND METHODS: 38 women whose foetuses were between 21-34 gestational age were studied. Indications for the examinations included the evaluation of non-CNS abnormalities in 25 cases. Foetal MR imaging was performed on a 1.5 T system (Edge, Marconi Medical System Italia SpA, Vimercate, MI) with the half-Fourier, single-shot, fast spin-echo EXPRESS sequence. Mild maternal and foetal sedation was obtained by oral administration of benzodiazepine (1 mg). RESULTS: In the 25 foetuses investigated for non-CNS pathologies the abnormalities were localised in the chest (9), abdomen (15) and extremities (1). The MR imaging diagnoses were: in the chest - congenital diaphragmatic hernia (CDH) (5), congenital cystic adenomatoid malformation (CCAM) (1), hydrothorax (1), cystic lymphangioma (1), Jeune syndrome (1); in the abdomen - 10 cases of urinary tract diseases - polycystic kidney (4), crossed renal ectopia (2), unilateral renal agenesis (1), solitary pelvic kidney (1), bilateral stenosis of ureteropelvic junction (1), duplex collecting system in association with controlateral hydroureteronephrosis (1)#151;5 cases of non-urinary tract pathologies#151;cystic lymphangioma of the liver (1), abdominal cystic lymphangioma (1), gastroschisis (1), gastric duplication (1), cavernous haemangioma of the liver (1); in the extremities - longitudinal hemimelia (1). CONCLUSIONS: In our experience MR is to be considered a useful though adjunct study to prenatal US particularly in the evaluation of lung parenchyma, congenital diaphragmatic viscera herniation, thoracic masses, pleural effusion, abdominal cystic masses, and urinary tract malformations. The ultrafast EXPRESS sequence enables a complete study to be performed in a very short time; as a consequence the examination is well tolerated by the patient. Currently there is no legislation which regulates the use of magnetic fields in MR, only a series of recommendations based on studies on animal embryos and foetuses, on pregnant women exposed to magnetic fields and follow-up studies of children exposed to MR during gestation. Therefore the decision to proceed with foetal MR should be made on a case-by-case basis in close consultation with the referring obstetrician. Considering the results, in our opinion the potential of MR in the evaluation of a wide variety of non-CNS foetal diseases will increase in the near future.

Testicular microlithiasis: US findings in six pediatric cases and literature review.

The aim of this article is to report on six pediatric cases of testicular microlithiasis (TM) and to review literature reports, in order to schedule US and/or other control examinations, particularly when concomitant focal or diffuse alterations of the testicular parenchymal structure are present, considering the possible association of TM with testicular tumors. Six patients (age range 4-12 years) underwent US examination for scrotal trauma (two cases) unilateral cryptorchidism (one case) follow-up after orchidopexy for bilateral cryptorchidism (one case), and varicocele (two cases). Five examinations were performed with high-frequency probes (10/13 MHz) and seven with 5/7.5-MHz frequency transducers. Follow-up US examinations were performed at different times depending on initial clinical indications, presence of underlying disease, and initial US findings. Two of the six patients underwent three US examinations, two patients underwent two US examinations, and the remaining two patients underwent only one US examination. The patients underwent a total of 12 US examinations. Microliths were bilateral in four patients and unilateral in two patients. In these two latter cases, the contralateral testis was, in one case, cryptorchid and could not be evaluated by US; in the other case it was small and hyperechogenic with orchidopexy sequelae. In three cases microliths were distributed throughout the testis. In the remaining three cases they were present in limited areas of parenchyma. As to the importance of microliths, it was defined as mild in three cases and moderate/severe in three cases. Intratubular testicular microlithiasis is a well-proved histological finding (biopsy or autopsy). More recent is the US demonstration of TM with consequent definition of its pattern: usually bilateral hyperechogenic multiple small foci without acoustic shadows with complete or partial extension to the parenchyma. Testicular microlithiasis is a rare finding. Moreover, the pediatric cases reported in the literature are very few. However, the use of high-frequency US transducers (10-13 MHz) has recently allowed an easier demonstration of this disease also in children. Of particular interest is the study of the still-debated association of microliths with other diseases such as neoplasms. Some aspects need further investigation, namely the real incidence of microliths in the healthy population, the incidence of tumors in patients with microliths, the differences between adults and children, and the different types of follow-up at different ages. In pediatric age, if TM represents an isolated sign, patients need non-invasive US follow-up until adult age. Only if TM is in association with focal lesions of testis parenchyma is it mandatory to perform biopsy or surgical treatment.

MRI "road-map" of normal age-related bone marrow. I. Cranial bone and spine.

We retrospectively reviewed 733 cranial and 250 spinal T1-weighted MR images of patients younger than 24 years to evaluate the bone marrow changes. The signal intensity of the bone marrow on short-TR/TE images was compared with that of fat and normal muscles in the contiguous region and graded. The signal intensity of all anatomic segments was as low as that of muscle, or inferior, in all patients younger than 3 months because of hematopoietic tissue and probably greater amounts of trabecular bone. The first anatomic segments of cranial bone to become hyperintense were the zygomatic bone and mandibular symphysis, followed by the presphenoid bone, basisphenoid, basiocciput, calvaria, and the petrous apex. After 3 years of age, most patients demonstrated pneumatization of the sphenoid sinus. We describe the most interesting changes in the developing spine, which occur in the first 2 years of life. The morphology of the vertebral bodies was evaluated. The variability of the signal and the morphology of the disks were also evaluated. Regional patterns of bone marrow signal intensity and age-related differences should not be misinterpreted as a pathologic condition.

MRI "road-map" of normal age-related bone marrow. II. Thorax, pelvis and extremities.

We retrospectively reviewed T1-weighted MR images of 381 patients aged from 7 days to 24 years to evaluate the bone marrow change in thoracic wall and shoulder, pelvis and proximal femur and upper and lower extremities. The patients included in the study were without history of bone marrow disease. A grade of from 1 to 4 was assigned to the marrow signal intensity of the examined anatomic segments. The signal intensity of all anatomic segments was as low as or lower than that of muscle in all patients younger than 2 months, reflecting underlying hematopoietic marrow. The first segments to become hyperintense were the epiphyseal/round bone ossification centers, followed by the phalanges, diaphysis, flat bones and metaphysis. Marrow signal intensity increased in all regions with age. While in the epiphysis, round bones and diaphysis bone marrow shows a diffuse and homogeneous increased signal intensity with age, in the sternum, ribs, scapulae, posterior ilium and metaphysis varying percentages of intermediate signal intensity are maintained. An orderly progression of red to yellow marrow was established.

Automobile driver fatalities in frontal impacts: air bags compared with manual belts.

OBJECTIVES: The effectiveness of air bags was estimated in this study by comparing driver fatalities in frontal crashes with driver fatalities in nonfrontal crashes, for cars with air bags and manual belts and cars with manual belts only. METHODS: Fatal Accident Reporting System data for drivers fatally injured during 1985 to 1991 in 1985 to 1991 model year cars that were equipped with air bags in or before model year 1991 were analyzed. RESULTS: Driver fatalities in frontal crashes in air bag cars were 28% lower than those in comparable cars with manual belts only. This percentage was used for estimating the overall fatality reduction in air bag cars. The reduction was greater in large cars (50%) than in midsize cars (19%) or in small cars (14%). Air bags reduced driver fatalities in frontal crashes involving ejection by about 9%. Fatalities in frontal crashes among drivers who were reportedly using manual belts at the time of the crash were reduced by about 15%. The comparable reduction among drivers who were reportedly not using manual belts was 31%. CONCLUSION: It was estimated that air bags reduced the total number of all driver fatalities by about 19%.

[The use of 3-dimensional CT reconstruction in childhood. Technics and dosimetry]. / Applicazioni della ricostruzione TC-tridimensionale nell'età pediatrica. Tecnica e dosimetria.

A new computer method has been developed that allows the reprocessing of standard CT scans to produce 3D surface images. We employed the 3D reconstruction program developed by Hitachi Medical System using an Ansaldo A-TOM XR 1200 scanner. The process requires only standard CT scanner hardware, and reconstruction time is comparable to that of sagittal and coronal reconstructions. The applications of this technique and methodology to pediatric patients are discussed. In order to assess the relationship between image quality and radiation dose, we performed many CT scans with different protocols. A skull was employed for phantom, and plunged into a physiological solution, which helped us to determine the radiation exposure dose from every single CT scan. The measurements were taken with film and thermoluminescent crystal dosimeters (TLD). The results confirm that low-dose techniques allow a significant reduction in the total exposure. The authors discuss the clinical indications and the eventual applications of these techniques.