Imaging of tuberculosis of the spine.

Tuberculosis (TB) is the leading cause of death worldwide that can be attributed to a single infectious agent. With the onset of the AIDS epidemic, there has been a resurgence of TB in recent years. Skeletal TB constitutes 1% to 3% of extrapulmonary cases, and typically involves the spine. TB of the spine should be considered in the differential diagnosis of many spinal conditions affecting patients of all ages. The pathophysiology, clinical and imaging features of TB of the spine are reviewed, with illustrations of findings on radiography, computed tomography and magnetic resonance imaging. Familiarity with the imaging features of TB of the spine may enable a more rapid diagnosis to be made, thereby preventing a delay in diagnosis with its consequent complications.

Castleman's disease of the neck: a description of four cases on contrast-enhanced CT.

Castleman's disease of the neck is an uncommon benign lymphoproliferative disease that usually presents as homogeneously enhancing enlarged lymph nodes on contrast-enhanced CT scan. We described the appearance of four confirmed cases of Castleman's disease of the neck on contrast-enhanced CT scan. Three of these presented as a solitary enhancing lymph node and the fourth case presented with multiple bilateral enhancing lymph nodes. A central non-enhancing area was present in two of the three cases that presented as a solitary node. Pathological correlation of one of these cases showed that this was due to a central fibrotic scar. One of the enhancing nodes in the fourth case with multiple and bilateral lymphadenopathy also contained a central non-enhancing area. We would like to propose that if a central non-enhancing scar is observed in an enhancing lymph node in the neck on CT scan, Castleman's disease should be considered as a possible diagnosis.

Clinics in diagnostic imaging (73). Left hydronephrosis due to pelvi-ureteric junction obstruction.

A full-term male infant was antenatally diagnosed to have left hydronephrosis. Post natal ultrasonography (US) and diuretic renography confirmed the diagnosis of left pelvi-ureteric junction obstruction. His clinical course was complicated by one episode of urinary tract infection. Serial US and diuretic renography showed no improvement in the obstruction. The patient underwent an Anderson-Hynes pyeloplasty at nine months of age with no post-operative complications. The diagnosis and management of antenatally-diagnosed hydronephrosis are discussed.

Clinics in diagnostic imaging (69). Bilateral developmental dysplasia of the hip.

Developmental dysplasia of the hip (DDH) is a condition encompassing a spectrum of abnormality. The ultrasonography features of DDH in a male infant is illustrated. Follow-up after treatment with a Pavlik harness shows resolution of the DDH. In the neonatal period, ultrasonography (US) is the modality of choice used to evaluate babies with suspected developmental dysplasia of the hip. The unossified cartilaginous femoral head and much of the acetabulum can be visualised on US. When the femoral head begins to ossify, pelvic radiographs can be used to follow-up patients with developmental dysplasia of the hips.

Intussusception: a three-year review.

INTRODUCTION: Intussusception is the commonest cause of intestinal obstruction in infants and young children. MATERIALS AND METHODS: This report reviews the clinical presentation, investigations and outcomes of patients with intussusception treated at the KK Women's and Children's Hospital between 1 May 1997 and 30 April 2000. RESULTS: The study population comprised 160 consecutive patients treated for intussusception at our hospital over this 3-year period. The commonest symptom was vomiting; present in 135 patients (84.4%). A palpable abdominal mass was present in 90 patients (56.3%). The classical features of vomiting, abdominal pain, abdominal mass and rectal bleeding were present together in only 12 patients (7.5%). Abdominal ultrasonography was performed in 155 patients. One hundred and fifty-two patients (98.1%) had the classical target lesion on ultrasonography. Air enema reduction was attempted in all except 6 patients. In the majority of patients (130 or 84.4%), the intussusception was reduced successfully by air enema reduction. There was no association between the duration of symptoms before radiological reduction and the outcome of radiological reduction. CONCLUSIONS: As the four classical features of intussusception were present together in only 7.5% of our patients, a high index of suspicion is necessary when any of the signs and symptoms are present in an infant or young child. Abdominal ultrasonography is the diagnostic investigation of choice. Air enema reduction was successful in 84.4% of patients and the duration of symptoms did not reduce the success rate. Thus, air enema reduction should be attempted in most patients unless they have absolute contraindications.

Focal nodular hyperplasia: an unusual liver mass in a paediatric patient.

We report an unusual case of focal nodular hyperplasia (FNH) occurring in a 19-month-old female without a typical central fibrous scar. Ultrasound demonstrated a solid, hypoechoic, highly vascular mass situated in the left lobe of the liver. Computed tomography showed a solid mass with no evidence of a central fibrous scar. A hepatic angiogram demonstrated enlarged right and left hepatic arteries supplying the vascular tumour, with early venous drainage into the inferior vena cava; a feature which has not been previously described. Surgical resection was carried out and a solid, nodular tumour measuring 9 x 4 x 4 cm was removed. The diagnosis of FNH was made histologically. The characteristic imaging findings of FNH will be discussed and a review of the literature of FNH in children will be presented.

MR imaging differentiation of soft-tissue hemangiomas from malignant soft-tissue masses.

OBJECTIVE: The purpose of this study was to determine whether MR imaging features can reliably distinguish hemangiomas from malignant soft-tissue masses. MATERIALS AND METHODS: We retrospectively reviewed MR imaging studies of 22 patients with soft-tissue hemangiomas and 22 patients with malignant soft-tissue masses. Images were reviewed and agreement reached by a consensus interpretation of two observers and by an independent observer. Masses were evaluated for signal intensity on T1- and T2-weighted images, for enhancement with gadolinium administration, and for morphology (lobulation, septation, central low-intensity dots). Lesion T2 signal and lesion enhancement with gadolinium administration were also objectively measured using regions of interest and comparison with skeletal muscle. RESULTS: Signal intensity on T1-weighted imaging of hemangiomas and malignant soft-tissue masses was similar. Subjective analysis showed greater T2 signal and gadolinium enhancement in hemangiomas; however, the differences were not statistically significant on objective analysis. Lobulation, septation, and central low-signal-intensity dots were all more common in hemangiomas, with statistical significance achieved; the combination of all three findings was specific for hemangioma. CONCLUSION: Although no single MR imaging feature was diagnostic in this study, analysis of lesion morphology, signal intensity, and enhancement with gadolinium allowed MR imaging differentiation of hemangiomas from malignant soft-tissue masses.

Ultrasonography and computed tomography in a clinical algorithm for the evaluation of suspected acute appendicitis in children.

AIM: To evaluate the roles and effectiveness of US and CT in a clinical algorithm for the evaluation of children with suspected appendicitis. METHODS: Patients with suspected appendicitis were prospectively evaluated with ultrasound (US), and in some cases with CT, after they were graded to have high, intermediate or low clinical likelihood for appendicitis. Imaging findings were made known to clinicians who then decided on a line of management. Patho-histological examination and clinical follow-up established the final diagnoses, which were correlated with the imaging findings. The effect of imaging on the management of patients was examined. RESULTS: Overall, the sensitivity of US was 92.9%, specificity 96.9%, accuracy 96.0%, positive predictive value 89.7% and negative predictive value 97.9%. Imaging did not affect the decision to operate in 13/14 (92.9%) patients in the high likelihood subgroup. Imaging guided the clinicians to the right management pathway in 26/30 (86.7%) patients in the intermediate group. 77/82 (93.9%) of US was truly negative in the low likelihood group. CT was performed in 12 patients because of unsatisfactory US scans or incompatibility between the US and the clinical findings. CT correctly diagnosed the presence or absence of appendicitis in all 12 patients. CONCLUSION: US and CT are accurate modalities in the diagnosis of acute appendicitis in children. US is most useful in patients with equivocal clinical findings. US should be the first modality used to evaluate children with suspected appendicitis. CT should be reserved for cases where US is sub-optimal or where the findings are inconsistent with the clinical findings.

Power Doppler evaluation of joint effusions: investigation in a rabbit model.

OBJECTIVE: To study the power Doppler findings of septic arthritis and noninfectious synovitis in an animal model. MATERIALS AND METHODS: The right knees of 10 rabbits were inoculated with an aqueous suspension of Staphylococcus aureus. The right knees of 5 rabbits were injected with talc suspension. The right knees of 5 rabbits were injected with saline. All 20 left knees were injected with saline. Serial power Doppler images were obtained using constant-imaging parameters. Images were reviewed by blinded observers who assessed for increased power Doppler signal. RESULTS: All 10 knees inoculated with S. aureus developed septic arthritis. Each infected rabbit knee demonstrated increased signal on power Doppler on at least one examination, ranging from 1-6 days after inoculation. Only 23 of 45 examinations of infected knees were unequivocally positive by power Doppler on examinations performed 1 to 6 days after inoculation. No knee with talc synovitis demonstrated increased power Doppler signal. No control knee demonstrated increased power Doppler signal. CONCLUSION: Increased power Doppler signal may be seen with septic arthritis; however, its intensity and timing may vary from subject to subject. A normal power Doppler examination does not exclude septic arthritis.

MRI evaluation of infectious and non-infectious synovitis: preliminary studies in a rabbit model.

BACKGROUND: Literature on magnetic resonance imaging (MR) evaluation of inflammatory joint effusions is sparse. OBJECTIVE: To describe an animal model for studying infectious and non-infectious joint effusions with magnetic resonance imaging. MATERIALS AND METHODS: Ten rabbit knees with septic arthritis and four with talc synovitis were imaged with MR. Contralateral knees injected with saline served as controls. Fat saturation T2-weighted and gadolinium-enhanced T1-weighted images were assessed for joint effusion, and periarticular and adjacent intraosseous increased signal or enhancement. Each knee was cultured and underwent pathologic examination. RESULTS: Both Staphylococcus aureus and talc produced effusions in all knees. The degree of periarticular signal and enhancement was greater in infected knees than talc-injected knees. No abnormal enhancement was seen within bone. Pathologic examination showed a greater degree of inflammation and joint destruction in the infected knees, but no evidence of osteomyelitis. CONCLUSION: A greater degree of abnormal signal and enhancement seen on MR suggests a more vigorous inflammatory process, as seen with septic arthritis. In spite of advanced septic arthritis, no enhancement was evident within bone, suggesting that enhancement within bone is not an expected finding in isolated septic arthritis and should raise concern for osteomyelitis.

Applications of magnetic resonance imaging and magnetic resonance angiography to evaluate the hepatic vasculature in the pediatric patient.

Magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) offer several techniques to evaluate the hepatic vasculature. These techniques are briefly reviewed with reference to the pediatric population. Examples of MRI and MRA in the evaluation of the hepatic vasculature in pediatric patients are presented.

Diffuse marrow disorders in children.

This article describes MR imaging findings in neoplastic processes affecting the marrow of children. Differentiation from non-neoplastic processes, such as edema and hematopoietic marrow is described.