Wendy Lam

Impact of Right Ventricular Dilation on Left Ventricular Myocardial Deformation in Patients After Surgical Repair of Tetralogy of Fallot

Left ventricular (LV) dysfunction is 1 of the major determinants of late adverse clinical outcomes in patients after surgical repair of tetralogy of Fallot (TOF). The aim of this study was to test the hypothesis that LV myocardial deformation is impaired in patients after TOF repair and related to right ventricular (RV) dilation and exercise capacity. Longitudinal, radial, and circumferential LV myocardial deformation was determined using speckle-tracking echocardiography in 23 postoperative patients with TOF and compared to that of 23 age-matched controls. Relations between LV strain and strain rate (SR) and RV volumes and exercise parameters were determined in patients. Compared to controls, patients had reduced global LV longitudinal, radial, and circumferential strain (all p values <0.05). Patients with significantly increased RV end-systolic volume (>2 SDs higher than normal; n = 17) had reduced global LV circumferential strain (p = 0.048) and SR (p = 0.038), but similar longitudinal and radial speckle-tracking echocardiographic parameters, compared to those without (n = 6). RV end-systolic volume was correlated inversely with global LV circumferential strain and SR (r = -0.58, p = 0.004, and r = -0.58, p = 0.005, respectively), while RV end-diastolic volume was correlated only with global LV circumferential strain (r = -0.43, p = 0.047). In patients, the LV ejection fraction was correlated with global LV circumferential strain (r = 0.54, p = 0.01) and SR (r = 0.66, p = 0.001) but not with longitudinal or radial speckle-tracking echocardiographic parameters. Using multivariate analysis, global LV circumferential SR (beta = 0.66, p = 0.001) and male gender (beta = 0.46, p = 0.012) were identified as independent predictors of peak oxygen consumption. In conclusion, the negative impact of RV dilation on LV function relates to its influence on LV circumferential strain and SR in patients after TOF repair.

Transverse testicular ectopia detected by MR imaging and MR venography

Abstract. Crossed testicular ectopia is a rare anomaly, characterised by migration of one testis towards the opposite inguinal canal. In most reported cases, the correct diagnosis was not made pre-operatively. We report a case of transverse testicular ectopia diagnosed pre-operatively with MRI. MRI and MR venography demonstrated unilateral location of both testes in the right inguinal canal, which was confirmed by surgery. We provide a brief literature review of transverse testicular ectopia and the imaging of undescended testis.

Ultrasonographic measurement of subarachnoid space in normal infants and children.

This study was undertaken to evaluate the sonographic measurement of subarachnoid spaces in normal children and its relationship with age and to define a normal range in a Chinese population and to differentiate normal variant findings from pathologic dilatation. The subarachnoid spaces in 278 normal term neonates, infants, and children were studied with real-time ultrasound using a 7.5-MHz vector transducer. The craniocortical width, sinocortical width, and interhemispheric width were measured in the coronal plane at the level of the foramen of Monro, on either side of the hemispheres. Correlation of sonographic measurements with age was made. The mean widths were plotted against age. A correlation with age was found in all three spaces, with an increasing trend with age until 28 weeks of gestation. Thereafter, a decreasing trend was noted. The normal upper limit of subarachnoid spaces for children is proposed to be the values on the ninety-fifth percentile of the regression curve. Correlation of measurement with age must be considered to decide whether an increase in subarachnoid space is pathologic or not.

Functional implications of the right ventricular myocardial performance index in patients after surgical repair of tetralogy of Fallot.

The myocardial performance index (MPI) has been proposed to be a simple echocardiographic index of right ventricular (RV) function in patients after surgical repair of tetralogy of Fallot (TOF). However, its functional status remains to be clarified. The functional implications of RV MPI were determined by exploring its relationships with parameters of RV function as derived from cardiovascular magnetic resonance (CMR), and exercise capacity of postoperative TOF patients Thirty patients (11 males), aged 15.6 ± 3.1 years, who have undergone surgical repair of TOF at 4.0 ± 1.8 years, were studied. The RV and left ventricular (LV) MPIs determined using pulsed-wave Doppler echocardiography were related to CMR-derived RV and LV ejection fractions, and pulmonary regurgitant fraction and treadmill exercise testing parameters. Log RV MPI correlated positively with log LV MPI (r = 0.38, P = 0.037) and negatively with CMR-derived RV ejection fraction (r = −0.4, P = 0.028) and pulmonary regurgitant fraction (r = −0.4, P = 0.031). No significant correlations were found between LV MPI and any of the CMR parameters. Using receiver operated characteristics analysis, a cutoff value of 0.30 for RV MPI was found to have a sensitivity of 100% and specificity of 74% in predicting a RV ejection fraction <35%. Right ventricular, but not LV, MPI correlated inversely with exercise duration (r = −0.45, P = 0.013) and peak oxygen consumption (VO2 max) (r = −0.56, P = 0.001). Multivariate analysis identified RV MPI (β = −0.6, P < 0.001), male sex (β = 0.44, P = 0.01), and duration from surgery (β = −0.30, P = 0.019) as significant determinants of VO2 max. Increased MPI is a reflection of reduced RV ejection fraction and exercise capacity in patients after TOF repair.

Paediatric thymoma: Unusual occurrence in two siblings

Invasive cystic thymoma is reported in two siblings (an 11-year-old girl and a 9-year-old boy) and the radiographic, CT and ultrasonographic features are described. The tumours were removed by thoracotomy. Familial thymic masses are reviewed, and the imaging differential diagnosis of cystic anterior mediastinal mass in a child is discussed.

Right Ventricular Mechanics in Adults after Surgical Repair of Tetralogy of Fallot: Insights from Three-Dimensional Speckle-Tracking Echocardiography

BACKGROUND The clinical relevance of evaluating right ventricular (RV) myocardial deformation in congenital heart disease is increasingly recognized. The aim of this study was to explore, using three-dimensional (3D) speckle-tracking echocardiography, RV mechanics in terms of 3D global area strain and mechanical dyssynchrony in adults with repaired tetralogy of Fallot. METHODS Twenty patients (12 men) aged 24.7 ± 8.6 years and 22 age-matched controls (11 men) were studied. Global RV peak area strain and area strain-derived systolic dyssynchrony index (SDI) were determined using 3D speckle-tracking echocardiography. RV end-diastolic volume and end-systolic volume, ejection fraction (EF), and pulmonary regurgitation fraction were measured in patients using cardiac magnetic resonance. RESULTS Coefficients of variation for intraobserver and interobserver measurements of RV global area strain were 6.1% and 7.9%, respectively, and those for SDI were 7.6% and 10.1%, respectively. Compared with controls, patients had significantly lower global area strain (P = .005) and greater SDI (P = .008). The prevalence of RV mechanical dyssynchrony (SDI > control mean + 2 SDs) in patients was 30%. In patients, global area strain correlated inversely with SDI (r = -0.42, P = .04), RV end-diastolic volume (r = -0.48, P = .032), and RV end-systolic volume (r = -0.48, P = .031) and positively with EF (r = -0.51, P = .02), while RV SDI correlated positively with RV end-systolic volume (r = 0.55, P = .012), pulmonary regurgitation fraction (r = 0.54, P = .031), and QRS duration (r = 0.51, P = .022) and negatively with RV EF (r = -0.62, P = .004). Multivariate analysis showed that RV EF (β = 0.22, P = .048) was a significant correlate of global area strain in patients. CONCLUSIONS In adults after tetralogy of Fallot repair, 3D RV deformation is impaired in association with RV dyssynchrony, volume overloading, and reduced EF.

H-type tracheo-oesophageal fistula: appearance on three-dimensional computed tomography and virtual bronchoscopy

Abstract. H-type tracheo-oesophageal fistula (TOF) is a rare type of fistula without oesophageal atresia. The symptoms are usually present at birth, but the diagnosis is often delayed. Traditionally, contrast oesophagography and/or fiberoptic bronchoscopy are used to confirm the diagnosis. We describe the imaging features of a case of H-type TOF seen on three-dimensional computed tomography and virtual bronchoscopy and the usefulness of these techniques in pre-operative evaluation.

Myocardial iron load and fibrosis in long term survivors of childhood leukemia

We sought to assess myocardial iron load and fibrosis, which may potentially affect cardiac function, in adult survivors of childhood leukemias and their relationships with left (LV) and right ventricular (RV) function.

Osteogenesis imperfecta type V

Osteogenesis imperfecta type V was first described in 2000. It is a distinct clinical entity with unique clinical, radiological, and histological features. Clinically, it is only moderately deforming. Patients have normal scleraand teeth. Radiological diagnostic criteria include a triad of calcification of the radioulnar interosseous membrane, presence of hypertrophic callus at fractures or post-operative sites, and radiodense metaphysealbandadjacenttogrowthplates(1). Histologically, it is distinguished by a mesh-like pattern of lamellation under polarized light microscopy for iliac bone samples. Ossification of the interosseous membrane of the forearm is a constant feature, although it may vary in its extent. The presence of ossification can severely limit movements of the forearm, and is associated with secondary dislocation of the radial head (1, 2). The frequency of radial head dislocation/subluxation is significantly higher in type V osteogenesis imperfecta (86%) than in the other types (0% to 29%) (3). The presence of interosseous membrane ossification in a pediatric patient, with or without radial head dislocation, should prompt radiologists to consider OI type Vas a diagnosis. The formationof hypertrophic callus, if present, isthe most conspicuous clinical symptom in OI type V (1). It is reported that while not all OI type V patients have hypertrophic callus formation, all patients with hypertrophic callus formation are OI type V in the proper clinical context (1, 4). Lesions form during the growth years at sites of rapid periosteal apposition. The long bones are most often affected, particularly in the lower extremities (4). Hypertrophic callus can be precipitated by fracture or surgery, or arise spontaneously. It can become very large or even mimic osteosarcoma (2, 5). In unclear cases, MRI and CT can be helpful in distinguishing hypertrophic callus from sarcoma (6, 7). Evolution of the lesions is variable, ranging from complete resolution to significant persisting morbidity.

Evaluation of cumulative effective dose and cancer risk from repetitive full spine imaging using EOS system: Impact to adolescent patients of different populations

OBJECTIVE To evaluate the effective dose and associated cancer risk using EOS system for scoliotic adolescent patients undergoing full spine imaging at different age of exposure; to demonstrate EOS system capable of delivering less radiation dose and hence of reducing cancer risk induction when compared with conventional digital X-ray systems; to obtain cumulative effective dose and cancer risk for both genders scoliotic adolescence of US and Hong Kong population. METHODS Organ absorbed doses of full spine exposed scoliotic adolescent patients using EOS system have been simulated with the use of patient imaging parameters input to the Monte Carlo software PCXMC. Gender specific effective dose has been calculated with the simulated organ absorbed dose using the ICRP-103 approach. The associated radiation induced cancer risk, expressed as lifetime attributable risk (LAR), has been estimated according to the method introduced in the Biological Effects of Ionizing Radiation VII report. Values of LAR were estimated for scoliotic patients exposed repetitively during their follow up period at different adolescent age for US and Hong Kong population. RESULTS The effective dose of full spine imaging with posteroanterior and lateral projection for patients exposed at the age between 10-18 years using the EOS system low dose protocol was calculated between 86 and 140μSv. The corresponding LAR for US and Hong Kong population was ranged between 0.81×10-6 and 6.00×10-6. Cumulative effective dose and cancer risk during follow-up period can be estimated using the results and are of information to patients and their parents. CONCLUSION With the use of computer simulation and analytic formulation, we obtained the cumulative effective dose and cancer risk at any age of exposure for adolescent patients of US and Hong Kong population undergoing repetitive full spine imaging using the EOS system. Female scoliotic patients would be at a statistically significant higher effective dose and cumulative cancer risk than the male patients undergoing the same EOS full spine imaging protocol.