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For other articles and previous issues click here. June 7, 2004 MRI
Incubators: Improve Imaging for Newborns A new incubator designed for use with MR equipment helps clinicians safely and efficiently obtain quality diagnostic images of infants, according to a study published in the May issue of Radiology. Imaging newborns provides its own logistical challenges, including monitoring circulation and constantly controlling temperature, airflow, and humidity. Consequently, few newborns are examined with MR imaging, which is, for many indications, the most accurate noninvasive diagnostic test. “MR imaging is the most desirable imaging test for many newborns because there is no exposure to radiation,” said the study’s lead author, Stefan Blüml, PhD, associate professor at The Saban Research Institute at Childrens Hospital Los Angeles and the University of Southern California Keck School of Medicine. “However, many sick newborns cannot be studied by MR, even when clinically indicated, because of concerns for their safety during transport and during the procedure.” The researchers conducted 13 MR imaging studies on babies to evaluate an MR-compatible incubator with air temperature and humidity regulation and integrated radiofrequency coils. Image quality was superior to images obtained with standard MR equipment. No complications were encountered, vital signs remained normal, and there was little axillary temperature fluctuation. Typically, MR imaging exams of infants are performed with the manufacturer’s one-size-fits-all coils designed for adult heads. The customized small coils used with the MR-compatible incubators reduce scan time and improve image resolution. The MR-compatible incubator permits the nursery staff to do most of the preexam preparation in the neonatal intensive care unit, increasing the safety to the infant, Blüml said. “We found that image quality was far superior to images obtained with standard MR equipment,” he said. “We believe that MR-compatible incubators are beneficial for babies and will be cost-efficient in the long run.” Blüml is hopeful that this new technology will allow more MR studies of newborns, which will result in earlier and improved diagnoses and enable early intervention, treatment, and neonatal clinical research. Collaborating with Blüml on this study were Philippe S. Friedlich, MD; Stephan G. Erberich, PhD; John C. Wood, MD, PhD; Istvan Seri, MD, PhD; and Marvin D. Nelson, Jr, MD. — Source: Radiological Society of North America
MRI is superior to ultrasound in both sensitivity and positive predictive value for cerebral palsy, according to a comparison study between MRI and ultrasound in very low birth weight (VLBW) infants conducted by researchers from Stanford University Medical Center. Pat Barnes, MD, presented results from the study at the American Roentgen Ray Society meeting last month in Miami. The researchers also found both ultrasound and MRI showed relatively high specificity and negative predictive value. Based on the study, the authors recommend that ultrasound screening be performed for all VLBW infants, including at near-term. “Since ultrasound is more readily available (including its portability in the intensive care setting) and less expensive, it is used first. If it shows findings predictive of cerebral palsy, then there is probably no need for MRI,” said Barnes, one of the authors of the study. “If conventional MRI is needed, then diffusion tensor imaging is done at that time and would be important to do, especially if the conventional MRI is negative or nonspecific.” According to the authors, other indications could also influence the choice of imaging technique used. “For managing the acutely ill preterm newborn, especially for intraventricular hemorrhage and posthemorrhagic hydrocephalus, ultrasound is indicated. If there are other or additional concerns—for example, white matter injury—then MRI with diffusion tensor imaging is clearly superior,” said Barnes. The researchers are also investigating the role of MR spectroscopy in predicting cerebral palsy in VLBW infants. According to Barnes, “We are just now collecting that data. The potential is that MR spectroscopy may detect metabolic changes when no macrostructural changes—by ultrasound or conventional MRI—or microstructural changes—by diffusion tensor imaging—are present.” — Source: American Roentgen Ray Society Imaging Arthritis: Portable
MRI Better Than X-ray
The article, “Identification of Wrist and Metacarpophalangeal Joint Erosions Using a Portable Magnetic Resonance Imaging System Compared to Conventional Radiographs,” reported on 132 patients with inflammatory arthritis. The investigators evaluated the hands and wrists of the patients using both the MagneVu 1000 portable MRI system and standard radiography. The MRI exams detected erosions in 95% of the patients at 78% of body locations. In contrast, standard radiography identified erosions in 59% of the patients and in 39% of body locations. The difference was statistically significant (p < 0.05) for both comparisons. “There was superior sensitivity to bone damage using the portable MR system compared to radiographs of the wrists and MCP [metacarpophalangeal] joints, suggesting that this scanner is extremely promising for assessment of inflammatory arthritis,” the authors wrote. John V. Cruses, MD; Frank G. Shellock, PhD; Siamak Dardashti, MD; Timothy W. James, PhD; and Orrin M. Troum, MD, performed the study and cowrote the paper. — Source: Journal of Rheumatology Chemical Shift
MRI for Evaluating Adrenal Adenomas Contrary to most radiologists’ perception, MRI may be more sensitive than unenhanced CT in evaluating adrenal adenomas, according to researchers at New York University (NYU) School of Medicine. “Adrenal adenomas are common, and most of the time they don’t really matter,” said Gary Israel, MD, an assistant professor of radiology at NYU and researcher in a study on the topic. “However, if a patient has symptoms associated with an adrenal mass or has a history of cancer, we need to be able to accurately characterize these masses.” Israel presented results of a study on the topic at the American Roentgen Ray Society last month in Miami. The encouraging results suggest that chemical shift MRI be further evaluated to determine whether it’s truly a better method for evaluating adenomas. Israel noted that most radiologists would probably say chemical shift MRI and unenhanced CT are equivalent in characterizing adrenal adenomas but that the comparison has not been thoroughly investigated. This study suggests MRI is more sensitive, Israel said. “We studied 40 patients—with 42 adrenal masses—who had undergone both a chemical shift MRI and unenhanced CT,” Israel said. “Of the 42 adrenal masses, 13 could not be characterized as a lipid-rich adenoma using unenhanced CT. However, MRI characterized eight of these 13 adrenal masses as adenomas.” — Source: American Roentgen Ray Society |
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