Biomedical subjects
Publications and source records attributed to D J Roebuck.
A 15-month-old male presented with severe gastrointestinal bleeding and heart failure. Imaging revealed a superior mesenteric artery arteriovenous malformation, associated with a congenital portosystemic shunt. The heart failure was cured by resection of the arteriovenous malformation.
BACKGROUND AND PURPOSE: Hemosiderin and white matter lesions are 2 of the most common neurologic complications found on MR imaging that may be related to cranial irradiation and intrathecal methotrexate (MTX) therapy in childhood acute lymphoblastic leukemia (ALL). We evaluated the brains of patients previously treated for ALL with cranial irradiation and intrathecal MTX with MR imaging and tested the hypothesis that these patients have more MR evidence of central nervous system (CNS) injury than control patients who are in complete remission following systemic chemotherapy without cranial irradiation. METHODS AND MATERIALS: ALL patients recruited from a pediatric cancer center data base were examined at 1.5T by using T1-weighted, T2-weighted, gradient echo (GE), and fluid-attenuated inversion recovery sequences. Patients treated in childhood for solid extracranial neoplasms were used as controls. RESULTS: Lesions consistent with old hemorrhage were detected in 23 (55%) of the ALL patients and in none of the control patients (P <.001). Of the 62 hemorrhages detected on the GE images, only 9 (15%) were shown on T2-weighted images. White matter abnormalities were found in 2 ALL patients (5%) and one control patient (5%). Old infarcts were seen in 2 ALL patients (10%). CONCLUSION: Cerebral hemorrhages related to radiation-induced vascular malformations, most of which are asymptomatic, are much more common in survivors of childhood ALL than previously thought. GE sequencing is more sensitive in detecting hemorrhagic lesions than T2-weighted sequencing and is to be included in imaging protocols for follow-up study of patients after cerebral radiation therapy.
AIM: To assess the relative accuracy of dynamic spiral computed tomography (CT) compared with tracheobronchography, in a population of ventilator dependent infants with suspected tracheobroncho-malacia (TBM). SETTING: Paediatric intensive care unit in a tertiary teaching hospital. PATIENTS AND METHODS: Infants referred for investigation and management of ventilator dependence and suspected of having TBM were recruited into the study. Tracheobronchography and CT were performed during the same admission by different investigators who were blinded to the results of the other investigation. The study was approved by the hospital research ethics committee, and signed parental consent was obtained. RESULTS: Sixteen infants were recruited into the study. Fifteen had been born prematurely, and five had cardiovascular malformations. In 10 patients there was good or partial correlation between the two investigations, but in six patients there was poor or no correlation. Bronchography consistently showed more dynamic abnormalities, although CT picked up an unsuspected double aortic arch. Radiation doses were 0.27-2.47 mSv with bronchography and 0.86-10.67 mSv with CT. CONCLUSIONS: Bronchography was a better investigation for diagnosing TBM and in determining opening pressures. Spiral CT is unreliable in the assessment of TBM in ventilator dependent infants. In addition, radiation doses were considerably higher with CT.
Paediatric oncology patients are prone to central nervous system (CNS) complications due to multiple factors including disorders of the blood cell counts (which include neutropenia, thrombocytopenia or hyperleukocytosis), immunosuppression, neurotoxicity of the treatment, CNS dysfunction due to failure of other organ systems, disease progression of the primary malignancy or metastases. Imaging plays an important role in the management of paediatric oncology patients presenting with acute neurological symptoms. This pictorial review is from our institutional experience on imaging children who are under the care of the Child Cancer Centre. The review consists of a spectrum of neurological complications in paediatric oncology patients. The complications can be classified as (1) cerebrovascular complications, (2) treatment-elated complications, (3) opportunistic infections and (4) tumoural involvement of the CNS. Computed tomography (CT) is the initial choice of investigation, which is easily available and helps to exclude major intracranial abnormality such as haemorrhage. If the CT is negative, magnetic resonance imaging (MRI) should be performed, which is more sensitive for detection of CNS lesions.
INTRODUCTION: Renal artery pseudoaneurysms may arise as a complication of percutaneous nephrolithotomy (PCNL). Prompt recognition and treatment is essential to arrest haemorrhage which may be life threatening. CLINICAL PICTURE: A patient with chronic aortic dissection and malrotated right kidney underwent PCNL for right renal calculus. He developed delayed gross haematuria. TREATMENT: Angiography showed a pseudoaneurysm arising from one of two right renal arteries, which in turn arose from the false lumen of the aortic dissection. The supplying artery was successfully embolised. CONCLUSION: Renal artery pseudoaneurysms can be successfully treated with prompt angiography and embolisation, even in the presence of renal malrotation and aortic dissection.
PURPOSE: To evaluate the long-term brain metabolite changes on (1)H-MRS in acute lymphoblastic leukemia (ALL) patients who had intrathecal methotrexate (ITMTX) and cranial irradiation (CRT) for central nervous system (CNS) prophylaxis against CNS relapse. METHODS AND MATERIALS: Thirty-seven ALL patients (12 females, 25 males) with history of ITMTX and CRT for CNS prophylaxis were studied. Age ranges at the time of diagnosis and at magnetic resonance examination were 0.8-13 years and 12-27 years, respectively. The interval since diagnosis was 5.6-19 years. T2-weighted and gradient-recalled echo (GRE) magnetic resonance imaging (MRI) and proton magnetic resonance spectroscopy ((1)H-MRS) were performed to assess brain injury. RESULTS: On MRI, 3 leukoencephalopathy (LEP) and 1 infarct were detected. Twenty-two patients had evidence of hemosiderin. On (1)H-MRS no statistically significant difference in choline (Cho)/creatine (Cr) and N-acetylaspartate (NAA)/Cr was associated with LEP. A lower Cho/Cr (p = 0.006) and NAA/Cr (p = 0.078) was observed in brains with hemosiderin. Linear-regression analysis showed no statistically significant relationship between NAA/Cr or Cho/Cr with age at diagnosis, but there was a statistically significant decreasing trend of NAA/Cr and Cho/Cr with the interval since diagnosis. CONCLUSION: Long-term brain injury in ALL survivors after CNS prophylaxis with ITMTX and CRT was reflected by decreasing NAA/Cr and Cho/Cr with the interval since diagnosis. The lower Cho/Cr associated with hemosiderin but not LEP suggested a different pathophysiology for these brain lesions.
Alveolar soft-part sarcoma (ASPS) is a rare tumour. Certain distinctive clinical and radiological features suggest the correct diagnosis. There is moderate predilection for young women. ASPS almost always arises in skeletal muscle and occurs most frequently in the lower limbs. There is often a long clinical history and a large mass at presentation. Two young females with ASPS presented with very vascular tumours in the thigh, with prominent intra- and extra-tumoural blood vessels. The imaging findings and the existing literature are reviewed.
BACKGROUND: Pancreatoblastoma is a rare tumour of childhood. Reports of the imaging appearances are limited. OBJECTIVE: To define the imaging features of pancreatoblastoma by analysis of four previously unreported cases and review of the literature. MATERIALS AND METHODS: Findings at CT (n = 4), US (n = 3) and MRI (n = 2) were retrospectively reviewed in four patients with pancreatoblastoma. A Medline search was performed to identify relevant literature. RESULTS: Pancreatoblastoma arises most frequently in the body and/or tail, or involves the entire pancreas. Ultrasonography, CT and MRI show variable imaging features, but should in most cases permit preoperative distinction of pancreatoblastoma from other tumours that occur in this region in infancy and childhood. Detection of metastases in the liver, lymph nodes and peritoneal cavity is not significantly better with any one of these three modalities. CONCLUSION: Preoperative imaging with US, CT and/or MRI will usually suggest a correct diagnosis of pancreatoblastoma. Contrary to previous reports, the tumour arises in the pancreatic head in a minority of cases.
Medulloepithelioma is a rare tumour with a very poor prognosis. The most frequent site in the central nervous system is the cerebral hemispheres. Appearances on MRI are very variable, possibly reflecting the divergent forms of differentiation seen at histological examination. We report a rare case of sellar and suprasellar medulloepithelioma in a 2-year-old boy and discuss the imaging, differential diagnosis and pathologic findings.
Vesicoureteric reflux (VUR) and renal scarring are commonly found in children with urinary tract infection (UTI). The prevalence of VUR and scarring may vary between racial groups. There are no published data on the prevalence of VUR and scarring in Chinese children with UTI. A retrospective, single-institution study was made of Hong Kong Chinese children aged less than 5 years with a documented UTI investigated by both micturating cystourethrography and dimercaptosuccinic acid scintigraphy. VUR was identified in 39% of 93 Chinese children with UTI. Renal scarring was present in 28% of boys, which is comparable with published data on Western children. Scarring appears to be less common in Chinese girls with UTI (11%) than in Western girls (30-38% from published data), and its severity is poorly related to VUR grade. There is a significant dependency relationship between grade of VUR and degree of scarring in Chinese boys (p < 0.05). In conclusion, renal scarring appears to be relatively uncommon in Chinese girls. The correlation between grade of VUR and degree of scarring in Chinese boys suggests a relationship, but provides no evidence about the direction of causation.
OBJECTIVE: The objective of this study is to evaluate the frequency and significance of unrecognized bone or soft-tissue injury in pediatric patients with elbow trauma assessed with radiographs alone. SUBJECTS AND METHODS: Fifty children (32 boys and 18 girls; mean age, 7.3 years; age range, 2-12 years) with acute elbow trauma were examined with radiography and MR imaging. Radiographs were categorized into those showing normal findings, an effusion, an equivocal fracture, or an unequivocal fracture. MR examinations were assessed for an effusion, fracture, transphyseal fracture extension, physeal injury, bone bruising, and ligament or muscle injury. Average clinical follow-up was 1.6 years (range, 6-28 months) after injury. RESULTS: Radiographs showed normal findings in seven children (14%), an effusion only in 17 children (34%), and an unequivocal or equivocal fracture in 26 children (52%). MR imaging showed an effusion in 48 children (96%); unequivocal fracture in 37 children (74%), including transphyseal fracture in seven children (14%) and other physeal injury in three children (6%); bone bruising in 45 children (90%); ligament injury in six children (14%); and muscle injury in 19 children (38%). A less severe spectrum of injury occurred in children with normal findings on radiographs than in those with an effusion or fracture seen on radiography. Follow-up radiographs did not help in the detection of radiographically occult fractures. MR findings had no appreciable effect on patient treatment and no value in predicting duration of convalescence or clinical outcome at an average of 1.6 years after injury. CONCLUSION: In children with elbow trauma, MR imaging reveals a broad spectrum of bone and soft-tissue injury beyond that recognizable radiographically. However, the additional information afforded by MR imaging has little bearing on treatment or clinical outcome.
BACKGROUND: The use of surveillance imaging in children with medulloblastoma has been criticised. The aim of this study was to determine what proportion of relapses are detected by surveillance and whether these are found at a relatively favourable stage. METHODS: This study was a retrospective review of the medical charts and imaging studies of 89 patients treated at a single children's cancer centre. Relapse was defined as evidence of an increase in volume of residual tumour of greater than 25% or the presence of metastases, or new onset of positive CSF cytology. Relapse was termed symptomatic if it was diagnosed by tests performed because of new symptoms that occurred in the interval between surveillance examinations. Asymptomatic relapse was diagnosed solely on the basis of surveillance imaging. Survival time to relapse was calculated from the date of the first surgical procedure. RESULTS: Surveillance imaging detected 17 (71%) of the 24 relapses that occurred later than 6 months after diagnosis. All seven patients who presented with symptoms between scans have died, with a median survival from relapse of 5 months. Median survival from relapse in the patients detected by surveillance was 44 months, and four remain alive at 44-75 months. The patients detected by surveillance tended to have less advanced disease, which was more amenable to salvage therapy. CONCLUSION: This type of study cannot prove that surveillance imaging improves survival in children with medulloblastoma because of the effects of lead time and length biases. Despite this, surveillance does appear to be effective in detecting potentially curable medulloblastoma relapses and should be offered to all patients.
BACKGROUND: Obstructive jaundice is an uncommon but important clinical problem in children with cancer. Percutaneous transhepatic biliary drainage is widely used to relieve malignant biliary obstruction in adults, but its use in children has not been well described. MATERIALS AND METHODS: Six patients aged between 1 and 17 years underwent external or internal-external biliary drainage to relieve malignant obstructive jaundice. Biochemical, haematological and microbiological parameters were measured before the procedure and repeated 7-9 days later. RESULTS: External or internal-external biliary drainage was technically successful in all patients. No patient developed clinically significant biliary sepsis. Asymptomatic duodenal perforation occurred in one patient with bulky duodenal tumour following conversion from external to internal-external drainage. CONCLUSIONS: External biliary drainage may be successfully performed in children with malignant obstructive jaundice.
AIM: Preauricular sinuses are a common congenital abnormality. This study was performed to determine their sonographic features. MATERIALS AND METHODS: Fifteen preauricular sinuses (in 13 patients) were examined using a 5-10 MHz transducer to evaluate the nature of the sinus. Surgical correlation was obtained in 11 cases. RESULTS: Sonography detected the sinus in all cases. The maximum width of the sinus tract was 3 mm; it showed a branching pattern in four (27%) patients. Nine sinuses (60%) led to a cystic component, and the remaining six (40%) showed terminal ramification. Gas was identified within the sinus in nine (60%) cases. In the patients that underwent surgery, the diagnosis and the relationship of the sinus/ cystic component to the superficial temporal artery (STA), anterior crus of the helix and the tragus was confirmed and correlated well with the sonographic findings. However, the branching pattern of the sinus tract was difficult to confirm. CONCLUSION: Sonography readily detects preauricular sinuses and demonstrates their relationship to the STA, anterior crus of the helix, and the tragus, and can therefore be helpful in pre-operative assessment. Ahuja, A. T. (2000). Clinical Radiology 55, 528-532.
The present study, conducted in Hong Kong, was designed to evaluate the clinical assessment and interobserver variation between doctors with different levels of training in the assessment of recurrent varicoceles, and to compare their findings with those made by ultrasound. Fifteen patients, previously operated for left varicocele testis, were evaluated clinically by four observers. The mean age was 12.9 years (range 8-15 years) at surgery. The testicular texture, size and flow with and without the Valsalva manoeuvre were determined by colour Doppler sonography. The follow-up time was 6-48 months after surgery. The echotexture of the testes was normal in all patients. The mean volumes of the left and right testes were equal after surgery (left 9.0 ml [range 2.4-15.2 ml and right 8.7 ml [range 3.4-15.6 ml]). There was large variation between observers in the predictability of both positive and negative clinical findings of varicocele testis when compared with ultrasound. Objective assessment in grading varicocele testis and testicular volume using ultrasound is required for both clinical management and scientific research.
BACKGROUND AND PURPOSE: Hemangioendothelioma is the most common parotid gland tumor of childhood, and is diagnosed on clinical grounds, supported by imaging findings. Previous work has suggested that MR is the best imaging technique for assessment of parotid hemangioendothelioma. Demonstration of a reliable sonographic appearance would reduce the need for MR imaging in infants with this lesion. METHODS: We performed high-frequency sonography (including color Doppler and power Doppler imaging) in three patients, each with a diagnosis of parotid hemangioendothelioma confirmed by clinical follow-up. Two patients were also examined with MR imaging and labeled red cell scintigraphy. RESULTS: All sonographic studies showed a homogeneous mass enlarging and replacing most or all of the visualized parotid gland, with a lobular internal structure, fine echogenic internal septations, and a mildly lobulated contour. Color Doppler and power Doppler imaging showed extremely high vascularity within the mass. Correlative MR images in two infants showed a well-defined lesion with uniform intense contrast enhancement. Labeled red cell scintigraphy showed a well-defined area of intense activity. CONCLUSION: In the presence of a typical clinical history, sonography and clinical follow-up alone may prove to be sufficient for safe management of parotid hemangioendothelioma. MR imaging or labeled red cell scintigraphy may only be required if the sonographic features are atypical. These findings require confirmation in a larger series of patients.
The incidence of deep venous thrombosis (DVT) and pulmonary embolism (PE) among Chinese is much lower than in Caucasians. The total number of inferior vena cava (IVC) filters inserted in regional hospitals in Canada (about 700 beds in Toronto General Hospital) and Hong Kong (about 1,250 beds in Pamela Youde Nethersole Eastern Hospital) also reflects this. Thirty-six IVC filters were deployed in Toronto General Hospital, compared to 8 IVC filters inserted in Pamela Youde Nethersole Eastern Hospital from August 1997 to September 1998. Despite this, the physician may encounter patients with thromboembolic disease who require inferior vena cava interruption. The usual indication will be pulmonary embolism with contraindications to, or failure or complications of, anticoagulation therapy. It is important for angiographers to be familiar with the technique of percutaneous insertion of IVC filters. The types of IVC filters, techniques of insertion and guidelines relating to the choice of a filter would be discussed.
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