A systematic literature review of magnetic resonance spectroscopy for the characterization of brain tumors.

BACKGROUND AND PURPOSE: Proton MR spectroscopy ((1)H-MR spectroscopy) is a potentially useful adjunct to anatomic MR imaging in the characterization of brain tumors. We performed an updated systematic review of the evidence. METHODS: We employed a standardized search strategy to find studies published during 2002-2004. We reviewed studies measuring diagnostic accuracy and diagnostic, therapeutic, or health impact of (1)H-MR spectroscopy. We abstracted information on study design, (1)H-MR spectroscopy technique, and methodologic quality. We categorized studies into 5 subgroups: (1) metastasis versus high-grade tumor; (2) high-versus low-grade tumor; (3) recurrent tumor versus radiation necrosis; (4) tumor extent; and (5) tumor versus non-neoplastic lesion. RESULTS: We identified 26 studies evaluating diagnostic performance, diagnostic impact, or therapeutic impact. No articles evaluated patient health or cost-effectiveness. Methodologic quality was mixed; most used histopathology as the reference standard but did not specify blinded interpretation of histopathology. One large study demonstrated a statistically significant increase in diagnostic accuracy for indeterminate brain lesions from 55%, based on MR imaging, to 71% after analysis of (1)H-MR spectroscopy. Several studies have found that (1)H-MR spectroscopy is highly accurate for distinguishing high- and low-grade gliomas, though the incremental benefit of (1)H-MR spectroscopy in this setting is less clear. Interpretation for the other clinical subgroups is limited by the small number of studies. CONCLUSION: The current evidence on the accuracy of (1)H-MR spectroscopy in the characterization of brain tumors is promising. However, additional high-quality studies are needed to convince policy makers. We present guidelines to help focus future research in this area.

Newborns with suspected occult spinal dysraphism: a cost-effectiveness analysis of diagnostic strategies.

OBJECTIVE: To assess the clinical and economic consequences of different diagnostic strategies in newborns with suspected occult spinal dysraphism. METHODS: A decision-analytic model was constructed to project the cost and health outcomes of magnetic resonance imaging (MRI), ultrasound (US), plain radiographs, and no imaging in newborns with suspected occult spinal dysraphism. Morbidity and mortality rates of early versus late diagnosis of dysraphism and the sensitivity and specificity of MRI, US, and plain radiographs were obtained from the literature. Cost estimates were obtained from a hospital cost accounting database and from the Medicaid fee schedule. RESULTS: We found that the choice of imaging strategy depends on the underlying risk of occult spinal dysraphism. In low-risk children with intergluteal dimple or newborns of diabetic mothers (pretest probability: 0.3%-0.34%), US was the most effective strategy with an incremental cost-effectiveness ratio of $55 100 per quality-adjusted life year gained. For children with lumbosacral dimples, who have a higher pretest probability of 3.8%, US was less costly and more effective than the other 3 strategies considered. In intermediate-risk newborns with low anorectal malformation (pretest probability: 27%), US was more effective and less costly than radiographs and no imaging. However, MRI was more effective than US at an incremental cost-effectiveness of $1000 per quality-adjusted life year gained. In the high-risk group that included high anorectal malformation, cloacal malformation, and exstrophy (pretest probability: 44%-46%), MRI was actually cost-saving when compared with the other diagnostic strategies. For the intermediate-risk group, we found our analysis to be sensitive to the costs and diagnostic performances (sensitivity and specificity) of MRI and US. Lower MRI cost or greater MRI diagnostic performance improved the cost-effectiveness of the MRI strategy, whereas lower US cost or greater US diagnostic performance worsened the cost-effectiveness of the MRI strategy. Therefore, individual or institutional expertise with a specific diagnostic modality (MRI versus US) may influence the optimal diagnostic strategy. CONCLUSIONS: In newborns with suspected occult dysraphism, appropriate selection of patients and diagnostic strategy may increase quality-adjusted life expectancy and decrease cost of medical work-up.

Children with headache suspected of having a brain tumor: a cost-effectiveness analysis of diagnostic strategies.

OBJECTIVE: To assess the clinical and economic consequences of 3 diagnostic strategies-magnetic resonance imaging (MRI), computed tomography followed by MRI for positive results (CT-MRI), and no neuroimaging with close clinical follow-up-in the evaluation of children with headache suspected of having a brain tumor. Three risk groups based on clinical variables were evaluated. MATERIALS AND METHODS: A decision-analytic Markov model and cost-effectiveness analysis was performed incorporating the risk group prior probability, MRI and CT sensitivity and specificity, tumor survival, progression rates, and cost per strategy. Outcomes were based on quality-adjusted life year (QALY) gained and incremental cost per QALY gained. RESULTS: For low-risk children with chronic nonmigraine headaches of >6 months' duration as the sole symptom (prior probability of brain tumor 0.01%), no neuroimaging with close clinical follow-up was less costly and more effective than the 2 neuroimaging strategies. For the intermediate-risk children with migraine headache and normal neurologic examination (prior probability of brain tumor 0.4%), CT-MRI was the most effective strategy but cost >$1 million per QALY gained compared with no neuroimaging. For high-risk children with headache of <6 months' duration and other clinical predictors of a brain tumor such as an abnormal neurologic examination (prior probability of brain tumor 4%), the most effective strategy was MRI, with cost-effectiveness ratio of $113 800 per QALY gained compared with no imaging. CONCLUSION: Our analysis suggests that MRI maximizes QALY gained at a reasonable cost-effectiveness ratio in children with headache at high risk of having a brain tumor. Conversely, the strategy of no imaging with close clinical follow-up is cost saving in low-risk children. Although the CT-MRI strategy maximizes QALY gained in the intermediate-risk patients, its additional cost per QALY gained is high. In children with headache, appropriate selection of patients and diagnostic strategy may maximize quality-adjusted life expectancy and decrease costs of medical workup.

Children with macrocrania: clinical and imaging predictors of disorders requiring surgery.

BACKGROUND AND PURPOSE: Macrocrania is a common pediatric clinical condition affecting up to 5% of the population. The purpose of this study was to determine clinical and imaging predictors that are useful in the differentiation of disorders requiring surgical treatment from those that can be treated medically in children with macrocrania. METHODS: In a 3-year 7-month retrospective study, 88 patients (median age, 8 months; interquartile range, 5--13 months) with macrocrania and no known underlying neurologic disorder underwent imaging of the brain (sonography, n = 36; CT, n = 31; MR imaging = 21). The study was conducted in a pediatric tertiary care referral center. Clinical and imaging data were correlated to final diagnosis by means of logistic regression and receiver operating characteristic curves. RESULTS: Sixteen (18%) of the patients had disorders requiring surgery: communicating hydrocephalus, n = 7; noncommunicating hydrocephalus, n = 3; hemorrhagic subdural collections, n = 3; neoplasm, n = 1; encysted cavum septi pellucidi, n = 1; and vein of Galen malformation, n = 1. Clinical predictors of disorders requiring surgery included vomiting (P =.007), labor instrumentation (P =.026), developmental delay (P =.008), and abnormal neurologic findings (P =.028). Imaging predictors of disorders requiring surgery included a focal space-occupying lesion (P <.0001) and moderate-to-severe ventriculomegaly (P <.0001). The diagnostic sensitivity of the combination of independent clinical and imaging predictors was higher than that of independent clinical predictors alone, being 100% (95% confidence interval = 96.9%, 100%) and 93.8% (95% confidence interval = 88.7%, 98.8%), respectively. A trend indicated that the area under the receiver operating characteristic curve for clinical plus imaging findings (0.95) was greater than that for clinical findings alone (0.85) (P =.09). An increase in the number of clinical and imaging predictors was highly correlated with an increased risk of a disorder requiring surgery (P <.0001). CONCLUSION: Baseline neuroimaging is indicated for children with macrocrania because the combination of clinical and imaging predictors has the best diagnostic performance in determining the need for surgical versus nonsurgical management.

Three-dimensional CT maximum intensity projections of the calvaria: a new approach for diagnosis of craniosynostosis and fractures.

Three-dimensional CT maximum intensity projection (MIP) can depict suture patency, extent of synostosis (ie, complete versus incomplete bone bridging), fracture extent and conspicuity, and 3D calvarial deformity as a single set of projections in children with suspected craniosynostosis or skull fracture. Three-dimensional CT MIP may provide, in only eight views, all the required information to make the diagnosis of craniosynostosis and calvarial fracture extent currently requiring the combined information of 3D CT shaded surface displays and 2D axial CT images (a total of 58 views), and in some cases complementary skull radiographs. Three-dimensional MIP can be added to calvarial helical (spiral) CT imaging with only 5 minutes of additional postprocessing time.

Computers in radiology. The sedation, analgesia, and contrast media computerized simulator: a new approach to train and evaluate radiologists' responses to critical incidents.

BACKGROUND: Awareness and preparedness to handle sedation, analgesia, and contrast-media complications are key in the daily radiology practice. OBJECTIVE: The purpose is to create a computerized simulator (PC-Windows-based) that uses a graphical interface to reproduce critical incidents in pediatric and adult patients undergoing a wide spectrum of radiologic sedation, analgesia and contrast media complications. MATERIALS AND METHODS: The computerized simulator has a comprehensive set of physiologic and pharmacologic models that predict patient response to management of sedation, analgesia, and contrast-media complications. Photorealistic images, real-time monitors, and mouse-driven information demonstrate in a virtual-reality fashion the behavior of the patient in crisis. RESULTS: Thirteen pediatric and adult radiology scenarios are illustrated encompassing areas such as pediatric radiology, neuroradiology, interventional radiology, and body imaging. The multiple case scenarios evaluate randomly the diagnostic and management performance of the radiologist in critical incidents such as oversedation, anaphylaxis, aspiration, airway obstruction, apnea, agitation, bronchospasm, hypotension, hypertension, cardiac arrest, bradycardia, tachycardia, and myocardial ischemia. The user must control the airway, breathing and circulation, and administer medications in a timely manner to save the simulated patient. On-line help is available in the program to suggest diagnostic and treatment steps to save the patient, and provide information about the medications. A printout of the case management can be obtained for evaluation or educational purposes. CONCLUSION: The interactive computerized simulator is a new approach to train and evaluate radiologists' responses to critical incidents encountered during radiologic sedation, analgesia, and contrast-media administration.

Efficacy of fast screening MR in children and adolescents with suspected intracranial tumors.

PURPOSE: Our purpose was to determine the sensitivity, specificity, and receiver operator characteristic (ROC) curve of a fast screening MR protocol in children and adolescents with suspected intracranial tumors. METHODS: One hundred forty-one patients (mean age, 9.7 years; range, 2 months to 23.5 years) with suspected brain tumor were entered in a case-control study. Eighty-seven patients had intracranial tumors (31 suprasellar/hypothalamic, 27 supratentorial, 26 infratentorial, and three pineal) and 54 patients in the control group had other disorders. Two neuroradiologists reviewed blindly a detailed three-sequence conventional protocol (acquisition time, 8 minutes 27 seconds) and a two-sequence fast screening MR protocol (acquisition time, 4 minutes 44 seconds). RESULTS: Sensitivity and specificity of the fast screening protocol for intracranial tumors was 100% and 92.6%, respectively. The areas under the ROC curves were 0.966 for the fast screening and 0.980 for the conventional MR protocol. No diagnostic performance difference was found between the ROC curves using the Az index. A kappa statistic of .93 for both examinations indicated excellent interobserver agreement. Additional MR sequences and other neuroimaging studies were not deemed necessary to exclude the presence of an intracranial tumor. CONCLUSION: A fast dual-plane brain MR protocol may be adequate to screen children and adolescents thought to have an intracranial tumor. The less than 5 minute acquisition time allows a complete examination (including preparation) to be performed in 10 to 15 minutes. Future studies are recommended before this time-efficient neuroimaging examination is incorporated into clinical practice.

Radiologic-Pathologic Conference of Children's Hospital Boston: intraconal mass in the orbit of an infant.

A 16-month-old boy presented with left exophthalmos. He was found to have an enhancing intraconal soft-tissue mass. The differential diagnosis of the mass is discussed. The lesion was proven to be a malignant ectomesenchymoma, a very unusual tumor.

Children with headache: clinical predictors of surgical space-occupying lesions and the role of neuroimaging.

PURPOSE: To determine clinical predictors useful in differentiation of surgical lesions from medically treated disorders and the role of neuroimaging in children with headache. MATERIALS' AND METHODS: In a 4-year retrospective study, 315 patients with headache and no known neurologic disorder underwent brain magnetic resonance (MR) imaging. Sixty-nine patients also underwent brain computed tomography (CT). Clinical data were correlated with findings from MR imaging and CT and the final diagnosis by means of logistic regression. RESULTS: Thirteen (4%) patients had surgical space-occupying lesions. Seven independent multivariate predictors of a surgical lesion were identified. Sleep-related headache and no family history of migraine were the strongest predictors. Other predictors included vomiting, absence of visual symptoms, headache of less than 6 months duration, confusion, and abnormal neurologic examination findings. A positive correlation between number of predictors and risk of surgical lesion was noted (P < .0001). No difference between MR imaging and CT was noted in detection of surgical space-occupying lesions, and there were no false-positive or false-negative surgical lesions detected with either modality on the basis of clinical follow-up. CONCLUSION: Children at high risk on the basis of these criteria usually require neuroimaging, while children at low risk may be safely followed up clinically without neuroimaging.

Radiologic-pathologic conference of Children's Hospital Boston: liver nodules after heart transplantation.

We report the case of a 16-year-old boy who presented 1(1)/2 years after heart transplantation with multiple lesions throughout the liver as demonstrated by ultrasonography and CT. Results of analyses revealed features diagnostic for post-transplant lymphoproliferative disorder, which rarely involves the liver.

CT of complications in pediatric lung transplantation.

The authors review the computed tomographic (CT) findings following single and double lung transplantation in children to show the spectrum of complications. The most common parenchymal complications following transplantation include acute rejection; chronic rejection or bronchiolitis obliterans; bacterial, viral, and fungal infections; and lymphoproliferative disorders. In acute and chronic rejection, CT shows ground-glass attenuation and interlobar septal thickening. The same CT findings are seen in bacterial and viral infections, with occasional pulmonary abscess seen in the former. Fungal infections are characterized by cavitary lesions, air-space disease, and mediastinal adenopathy on CT scans. In lymphoproliferative disorders, CT demonstrates pulmonary nodules or soft-tissue masses. The most frequent posttransplantation airway complications include stenosis, stent migration, and dehiscence. Dehiscence, which usually results from ischemia at the anastomosis site, is evident on CT scans as a disrupted airway and extraluminal air collections. CT is particularly important in the evaluation of airway complications because the CT results can significantly affect patient management. In parenchymal disease, CT often cannot aid in establishing a specific diagnosis, but it can be used to determine a site for biopsy, document extent of disease, and follow up results of treatment.

Isolated lung transplantation in children: pathological diagnosis and incidence of pulmonary complications.

The pathological findings in the allografts of 14 children who underwent lung transplantation (LT) at St. Louis Children's Hospital, St. Louis, MO, in the period between July 1990 and May 1992 were reviewed. The study is based on histological analysis of 63 transbronchial biopsy (TBB) specimens, eight open lung biopsy specimens, and three pneumonectomy specimens. The mean age at transplantation was 10.5 years (range, 1 to 17 years) and the average follow-up period was 5.7 months. Sufficient tissue for an adequate pathological examination was obtained in 58 (92%) TBB specimens. Each specimen consisted of a mean of 6.12 tissue fragments, but only 4.79 fragments contained actual lung parenchyma for suitable examination. Ten patients (71%) had 23 biopsy-proven episodes of acute rejection with a frequency of 1.64 episodes per patient. The first episode was documented at a mean of 19 days after transplantation. Six patients (42.8%) developed bronchiolitis obliterans (BO). The definitive diagnosis of this condition was made either by open lung biopsy (n = 3) or on allograft pneumonectomy (n = 1), and it was infrequently recognized by TBB. Four of the six patients died less than 9 months after the diagnosis of BO was made, indicating the grave consequences of this complication. Two other deaths were attributed to the development of posttransplantation lymphoproliferative disorders.

Diagnosis of pulmonary complications associated with lung transplantation in children: value of CT vs histopathologic studies.

OBJECTIVE: The purpose of this study was to compare the CT findings with those of histopathologic studies to determine if CT can be used to differentiate between the pulmonary parenchymal complications that occur in children after lung transplantation. MATERIALS AND METHODS: Seventeen children who underwent 14 bilateral and three single lung transplantations were studied. The study population included nine girls and eight boys 2-16 years old (mean, 11 years). CT scans were examined for evidence of interlobular septal thickening, air-space consolidation, ground-glass opacities, nodules, bronchial dilatation, decreased vascularity, and pleural effusions. Thirty-one histopathologic diagnoses from 25 transbronchial biopsies were available for comparison with CT findings. The final histopathologic diagnoses were acute rejection (n = 10), chronic rejection (n = 6), infection (n = 7), nonspecific findings (n = 4), and no abnormalities (n = 4). RESULTS: No significant difference was noted in the CT findings in patients with acute rejection, chronic rejection, and infection. CONCLUSION: In this limited study of children, CT findings were not helpful in differentiating between the different parenchymal pulmonary complications associated with lung transplantation. On the basis of these preliminary findings, we recommend caution in suggesting specific diagnoses based on CT scans without histologic proof.

Pediatric lung transplantation: radiographic-histopathologic correlation.

Chest radiographic and histopathologic findings were retrospectively reviewed to determine the spectrum of findings in 16 children who underwent a total of 19 lung transplantations. Radiographs were evaluated for air-space disease, interstitial disease, Kerley B lines, pleural fluid, and cardiac size, and the interval from transplantation to the onset of complications was determined. Radiographic findings were correlated with 62 histopathologic diagnoses obtained from 51 transbronchial and open lung biopsy specimens. The final histopathologic diagnoses were acute rejection (n = 19), chronic rejection (n = 8), infection (n = 11), lymphoproliferative disorder (n = 4), and nonspecific (n = 20). The radiographic patterns of the complications were not significantly different. Seventy-nine percent (15 of 19) of episodes of acute rejection and 64% (seven of 11) of episodes of infection occurred within 5 weeks of transplantation, while 63% (five of eight) of the episodes of chronic rejection occurred after this period. Since chest radiographs are nonspecific, caution should be exercised in basing clinical decisions only on the radiographic pattern in the absence of corroborative clinical and histopathologic findings.

Imaging rounds #109. Intraosseous ganglia of the scaphoid.

An intraosseous ganglion is a relatively uncommon, benign, cyst-like lesion that occurs in middle-aged adults, and has a predilection for the tibia. Roentgenographically, it commonly appears as well a well-defined osteolytic lesion with a surrounding area of sclerosis.