Simultaneously Acquired MRI Arterial Spin-Labeling and Interictal FDG-PET Improves Diagnosis of Pediatric Temporal Lobe Epilepsy.

BACKGROUND AND PURPOSE: Interictal FDG-PET scans are a routine diagnostic technique for the identification of epileptogenic foci in the presurgical work-up of medically refractory pediatric epilepsy. With the advent of PET/MR imaging, it has become possible to simultaneously acquire FDG-PET and arterial spin-labeling perfusion data. The objective of this study was to evaluate whether the incorporation of arterial spin-labeling data with interictal FDG-PET could improve the diagnostic performance metrics of FDG-PET for identification of epileptogenic foci. MATERIALS AND METHODS: Forty-five pediatric patients with a mean age of 10.8 years were retrospectively included in this study. These patients all underwent PET/MR imaging to diagnose suspected focal epilepsy. RESULTS: When compared to interpretations of interictal FDG findings alone, FDG combined with arterial spin-labeling findings resulted in significantly decreased sensitivity (0.64 versus 0.52, P = .02), significantly increased specificity (0.50 versus 0.75, P = .04), and an increased positive predictive value (0.59 versus 0.75). The decreased sensitivity was found to be primarily driven by patients with extratemporal lobe epilepsy, as a subgroup analysis showed decreased sensitivity for patients with extratemporal epilepsy (0.52 versus 0.38, P = .04), but not for temporal epilepsy (0.83 versus 0.75, P = .16). Additionally, substantial agreement between focal FDG hypometabolism and arterial spin-labeling hypoperfusion was demonstrated with the Cohen κ (0.70, P < .01). CONCLUSIONS: These findings suggest that simultaneously acquired interictal FDG-PET and arterial spin-labeling data can improve the diagnosis of epileptogenic foci, especially in the setting of temporal lobe epilepsy where they improve specificity and positive predictive value, with preservation of sensitivity.

Thallium-201 for oncological imaging in children.

Many pediatric centers are beginning to accumulate a large experience in the use of thallium-201 (201Tl) imaging with 201Tl requires a state-of-the-art high-resolution gamma camera computer system with single photon emission computed tomography (SPECT) capability and a physician-directed tailored examination. Tumor imaging with 201Tl, with its multifactorial localization mechanisms that are different from those for gallium-67, offers a distinct advantage over gallium tumor imaging with a short total imaging time. Tumors are variable in avidity and intensity of thallium uptake. Primary and metastatic disease can be detected with 201Tl scintigraphy. Baseline pretreatment determination of thallium avidity is crucial to its efficacy in therapeutic response assessment. Adjunctive SPECT imaging provides greater sensitivity for lesion detection and direct comparison of physiology (thallium uptake) with anatomy (computed tomography and magnetic resonance imaging). The sensitivity and specificity for detection of pediatric brain tumors has been reported as 77% and 93%, respectively. Thallium-201 brain SPECT also provides a less expensive and more readily available alternative to positron emission tomography for assessing the functional state of pediatric brain tumors. Extremity osteogenic sarcoma and Ewing's sarcoma have 100% sensitivity for 201Tl uptake pretreatment. Early results confirm an association between 201Tl uptake and histological tumor response. The determination of residual/recurrent disease versus thymic rebound and other nonneoplastic change in thallium-avid lymphoma, rhabdomyosarcoma, and germ cell tumors that involve the thorax can be confirmed with a 201Tl SPECT examination. Soft-tissue tumors elsewhere in the body may be detected with 201Tl scintigraphy. Thallium-201 does not exhibit 100% specificity for tumors. False-positive 201Tl uptake has been seen in histiocytosis X, benign bone tumors, stress fractures, and inflammation.

Hepatobiliary scintigraphy in children.

Hepatobiliary scintigraphy using iminodiacetic (IDA) radiopharmaceuticals provides clinically useful information on the function of the biliary tract in a variety of pathological processes in children, including neonatal jaundice, gallbladder dysfunction, trauma, and liver transplantation. Phenobarbital premedication (5 mg/kg per day for a minimum of 5 days in divided doses) is used in infants who are being examined for neonatal jaundice to increase the accuracy of 99mTc-IDA scintigraphy in differentiating extrahepatic biliary atresia from neonatal hepatitis. Biliary atresia can be ruled out in an infant if a patent biliary tree is shown with passage of activity into the bowel. If no radiopharmaceutical is noted in the bowel on imaging up to 24 hours, distinction between severe hepatocellular disease and biliary atresia cannot be made. The literature reports 91% accuracy, 97% sensitivity, and 82% specificity for hepatobiliary imaging in the diagnosis of biliary atresia. The impairment of both intrahepatic and extrahepatic biliary drainage is an important cause of liver disease in cystic fibrosis. Hepatobiliary scintigraphy in cystic fibrosis has shown characteristic patterns of dilatation of mainly the left hepatic duct, narrowing of the distal common bile duct, gallbladder dysfunction, and delayed bowel transit. Cholecystitis in children may be acalculous. Sensitivity and specificity for the scintigraphic diagnosis of acute acalculous cholecystitis is reported to range from 68% to 93% and 38% to 93%, respectively. Cholescintigraphy in a suspected bile leak provides information generally not available with other techniques, except for direct cholangiography. If the amount of intraperitoneal accumulation of the tracer is greater than that entering the gastrointestinal tract, surgery is usually indicated. Hepatobiliary imaging in children who have undergone liver transplantation will assess graft vascularity, parenchymal function, biliary drainage, presence of a leak, and obstruction.

Lung volumes, mechanics, and perfusion after pulmonary resection in infancy.

Partial pulmonary resection in early childhood is well tolerated. Although long-term outcome has been described in several follow-up studies, almost no information is available on postoperative lung perfusion. We studied 14 patients 3 to 20 years (mean, 11.6 years) after they underwent partial pulmonary resection at 1 week to 30 months of age (mean, 6.8 months). We examined development, pulmonary function, endurance, radiographs and ventilation-perfusion scans. We used predicted pulmonary function test values, which were corrected for the relative amount of lung removed and called predicted-corrected values. We hypothesized that the remaining lung would have altered ventilation-perfusion characteristics. We found no abnormalities in the patients' physical development. Most children had abnormal regional ventilation, but normal equilibration occurred; five patients had gas retention; all had decreased perfusion to the area of resection; nine patients showed ventilation-perfusion mismatch characterized by dead-space ventilation. Lung volumes were within the predicted range in 12 patients. Residual volume and functional residual capacity were larger than predicted-corrected values in most patients but residual volume in relation to total lung capacity was at or below normal in 6 of 11 and did not correlate with the amount of lung removed. Most patients had prolonged expiratory flows. We conclude that lung resection in early childhood leads to good functional recovery. However, decreased expiratory flows, regional ventilation abnormalities, and decreased perfusion suggest dysplastic parenchyma and vascular bed in the area of resection.

Nuclear medicine topics in pediatric musculoskeletal disease: techniques and applications.

Musculoskeletal scintigraphy has excellent sensitivity for the evaluation of benign disease in children. Using illustrative cases, a spectrum of techniques and applications of nuclear medicine studies for benign bone diseases are presented. An approach to the use and evaluation of bone density evaluation in children also is discussed.

B mode ultrasonography--spectrum of paediatric ocular disease.

BACKGROUND: Despite having appropriate sonographic equipment available many radiologists remain unfamiliar with B mode sonography of the eye. OBJECTIVE: This article reviews the advantages and disadvantages of B mode sonography of the paediatric eye. We illustrate the spectrum of eye abnormalities occurring in paediatric practice and the sonographic appearance of clinical entities for which sonography is appropriate. MATERIALS AND METHOD: We reviewed our experience of eye sonography within a paediatric radiology department over 8 years. A total of 212 sonographic examinations were performed on 206 eyes in 103 children, aged from 3 days to 16 years (mean 4.6 years). RESULTS: Sonography was well tolerated by the children, was a very useful imaging modality and was the only diagnostic imaging modality required in 94%. Supplementary computed tomography (CT) was performed in ten of 206 eyes (5%) and magnetic resonance imaging (MR) was performed in two of 206 eyes (1%). CONCLUSIONS: B mode sonography is a very useful imaging modality for suspected ocular or orbital pathology in children and is often the appropriate first line investigation following clinical evaluation. Radiologists familiar with sonography of the eye can provide valuable support to their ophthalmology colleagues.

Laparoscopy as a cause of a false-positive Meckel's scan.

A new cause of a false-positive result of a Meckel's scan is reported. An 11-year-old girl had a 3-week history of constant right lower quadrant pain that was initially managed by laparoscopic appendectomy. A repeated laparoscopy for persistent pain was nondiagnostic. A missed Meckel's diverticulum was considered as the cause of this pain, which prompted a Meckel scan. This scan revealed a periumbilical focus of activity that was interpreted as a Meckel's diverticulum attached to the anterior abdominal wall by a band. The laparotomy showed no Meckel's diverticulum. The false-positive result of the Meckel scan may be the result of inflammation from the periumbilical laparoscopic port site.

Pediatric radiologic imaging.

Medical imaging in the pediatric age group presents special problems. The modern pediatric radiology department is a specialized area, and ensuring an adequate examination requires meticulous care from technician, radiologist and referring clinician. Radiation dose must be kept to a minimum, and constant modifications are being made to the "routine" methods of investigating common problems. These modifications include the introduction and rational integration of all the newer modalities. This presentation offers a modern diagnostic approach to a variety of common pediatric clinical problems.

Where are we with nuclear medicine in pediatrics?

The practice of nuclear medicine in children is different from that in adults. Technical considerations including immobilization, dosing of radiopharmaceuticals, and instrumentation are of major importance. Image magnification and the capability to perform single-photon emission tomography are essential to performing state of the art pediatric nuclear medicine. New advances in instrumentation with multiple detector imaging, the possibility of clinical positron emission tomography imaging in children, and new radiopharmaceuticals will further enhance pediatric scintigraphic imaging. This review highlights advances in pediatric nuclear medicine and discusses selected clinical problems.

The DMSA scan in paediatric urinary tract infection.

The objective of the present paper was to review the use of the dimercaptosuccinic acid (DMSA) scan in urinary tract infection at British Columbia's Children's Hospital to determine the frequency of cortical defects and the association between vesico-ureteric reflux and the presence of cortical defects in children with urinary tract infection. A total of 129 consecutive children with a urinary tract infection referred for a DMSA scan in a 2-year period (January 1992-January 1994) were retrospectively studied. The results were analysed in terms of kidneys, and the incidence of cortical defects was determined. Eighty-eight patients (68%) had a radiographic micturating cysto-urethrogram within 6 months of the DMSA scan, and in this group the relationship of defects with vesico-ureteric reflux was determined. Overall, 81/258 (31%) of kidneys had a cortical defect on a DMSA scan. Of those who had a micturating cysto-urethrogram, 53/176 (30%) kidneys had vesico-ureteric reflux, and of those that had reflux, 21/53 (40%) had a cortical defect on a DMSA scan. In the group of children without reflux, 38/123 (31%) had a cortical defect. Renal cortical scan defects are common findings in paediatric urinary infection, and frequently occur in the absence of vesico-ureteric reflux. These defects represent either established scars or acute pyelonephritis that can proceed to scarring. The micturating cysto-urethrogram alone is insufficient as a screening modality to identify those kidneys at risk of renal scarring.

The immotile cilia syndrome: radiological manifestations.

The immotile cilia syndrome (ICS) is an uncommon disorder characterized by specific and genetically determined defects of cilia that cause upper and lower respiratory disease. We reviewed the radiographic patterns in 30 patients who had ICS (15 females, 15 males) and ranged in age from newborn to 26 years. Except for two neonates, sinusitis and otitis were present in all patients. Chest radiographic abnormalities, universally present, included bronchial wall thickening, hyper-inflation, segmental atelectasis or consolidation, and segmental bronchiectasis. Situs inversus, present in 50% (7 females, 8 males), was not an essential part of this disorder. Radiologically, the disease progresses from bronchial wall thickening with or without hyperinflation, to increasing hyperinflation plus parenchymal changes including segmental atelectasis, consolidation, and bronchiectasis. There is also a predilection for anatomic middle lobe abnormalities. The radiological appearance and clinical state have similarities to cystic fibrosis, although they are less severe and less progressive. ICS should be considered in the differential diagnosis of slowly progressive chronic lung disease, sinusitis, and otitis.

Obstructive lung disease in children after allogeneic bone marrow transplantation: evaluation with high-resolution CT.

OBJECTIVE: Obstructive lung disease is a major complication of bone marrow transplantation related to graft-versus-host disease. The purpose of this study was to determine the usefulness of high-resolution CT to evaluate obstructive lung disease occurring in children after bone marrow transplantation. MATERIALS AND METHODS: Ten high-resolution CT scans of the lungs were obtained in seven children who developed chronic obstructive lung disease after bone marrow transplantation. All seven patients had chronic graft-versus-host disease. Spirometry, the gold standard test, confirmed airflow obstruction in each case, five prior to high-resolution CT. Two patients were too young to have spirometry until 10 and 15 months respectively after successful high-resolution CT. Selected images from these studies were randomized with similar images from five control subjects and reviewed blindly. All images from scans in patients with obstructive lung disease were analyzed retrospectively for parenchymal hypoattenuation, bronchial dilatation, bronchial wall thickening, and abnormal parenchymal opacity. Expiratory air-trapping was assessed on cine high-resolution CT done in four cases. RESULTS: Three blinded observers each correctly identified all five controls among 15 high-resolution CT examinations. No scan from a patient with obstructive lung disease was considered normal. Areas of parenchymal hypoattenuation affected 35 of 35 lobes of the lung. Expiratory air-trapping was shown by cine high-resolution CT. Subsegmental or segmental bronchial dilatation was seen in 23 of 25 lobes in five patients. Bronchial wall thickening was not a prominent feature. Increasing abnormality was demonstrated in three patients on follow-up high-resolution CT. The high-resolution CT abnormalities were similar to those reported in patients with bronchiolitis obliterans. CONCLUSION: High-resolution CT of the lungs can show extensive abnormality in children who develop chronic obstructive lung disease after bone marrow transplantation. High-resolution CT is a useful noninvasive technique in the evaluation of this disease.

Neonatal renomegaly.

A retrospective clinical review was done to study the value of ultrasound and renography in the investigation of 100 neonates with renomegaly. Abnormalities in 73 patients were detected antenatally with ultrasonography. Of the neonates 47 had lower urinary tract pathological conditions and ultrasound was more than 90 per cent accurate in identifying the accompanying ureteral dilatation. A total of 53 neonates had upper tract anomalies (ureteropelvic junction obstruction or cystic dysplasia). With ultrasonography the degree of pyelocaliectasis in patients with ureteropelvic junction obstruction was classified as mild (22 units), moderate (13) or severe (7). Initial treatment and followup were reviewed to study the clinical course of neonates with mild to moderate degrees of pyelocaliectasis followed nonoperatively, and to determine whether the diuretic renogram had a predictive role in identifying which kidneys were most likely to deteriorate.