Frederick R. Long

Lateral thoracic expansion for jeune syndrome: Evidence of rib healing and new bone formation

BACKGROUND Lateral thoracic expansion is a procedure that has been described to enlarge the thoracic cage in patients with Jeunes asphyxiating thoracic dystrophy. The procedure involves separating ribs from their periosteum and plating them together in an expanded fashion with titanium struts. We have speculated that the ribs heal in this situation, despite the absence of surrounding periosteum, and that new rib formation occurs in the liberated periosteum. METHODS Radiographic studies of patients who have undergone lateral thoracic expansion were reviewed for evidence of rib healing or periosteal new bone formation. RESULTS This study presents radiologic evidence that rib healing actually occurs, as does periosteal ossification. CONCLUSIONS Lateral thoracic expansion creates additional chest wall that is formed of autologous tissue, fully healed, and not ultimately dependent on titanium struts.

CT of Pediatric Vascular Stents Used to Treat Congenital Heart Disease

OBJECTIVE The purpose of our study was to assess the visibility of lumen narrowing of pediatric vascular stents using various CT dose parameters in an in vitro model. MATERIALS AND METHODS Ten steel stents of varying designs and sizes commonly used in the treatment of congenital heart disease were implanted in polyvinyl chloride (PVC) tubes and three of the 10 stents were partially obstructed with wax by filling 25% (mild) to 60% (moderate) of the lumen with contrast material. On a 64-MDCT scanner, the stents were scanned at tube voltages (kVp) of 80, 100, and 120 and at tube currents (mA) of 40, 80, 120, and 160. CT measurements of inner-stent diameter, strut thickness, and percent lumen (in-stent) stenoses were compared with biplane fluoroscopy of digital angiography. RESULTS The stent diameter and percent stenosis on all CT images were consistently smaller than measured on digital angiography but were highly correlated (r = 0.97; p < 0.0001) with improvement as stent diameter increased (93% agreement with digital angiography for 4-mm stent, up to 99% for 25-mm stent; p = 0.001). Moderate stenosis could be assessed better than mild stenosis (99% vs 91% agreement with digital angiography; p = 0.003). Increasing exposure settings improved CT correlation of all measurements for mA up to 120 and kVp up to 100 (98.1% agreement). Higher settings did not improve accuracy (93.9% for 160 mA at 120 kVp; p = 0.03). CONCLUSION CT is feasible to assess lumen narrowing of pediatric vascular stents at a wide range of tube settings. The study suggests that it is possible to lower the radiation exposure settings without loss in image quality or accuracy in detecting in-stent stenoses.

Assessment of in-stent stenosis in small children with congenital heart disease using multi-detector computed tomography : A validation study

Objectives: Our purpose was to investigate the diagnostic reliability of multi‐detector computed tomography (MDCT) in assessing in‐stent stenosis compared to digital angiography (DA) in small children. Background: Little is known about the feasibility of using MDCT to assess stents placed to treat children with congenital heart disease (CHD). Methods: Twenty‐two children (median age [range], 2¾ [½ to 12] years) with 42 transcatheter placed stents (median diameter: 7.2 [3.4–16.3] mm) in the pulmonary arteries (n = 36), aorta (2), PDA (1), and SVC (3) underwent both MDCT and DA due to suspected hemodynamic problems. Results: Independent “blinded” observers were able to measure stent and minimal luminal diameters in 115 out of 124 (93%) stent segments on MDCT and DA. The interobserver variability was low (mean difference: 0.5, SD 0.8 mm) with high correlation (r = 0.97; P < .0001). The percent stenosis by MDCT correlated well with DA (r = 0.89, P < .0001; mean error 2.7, SD 10.4%). For all grades of stenosis, the sensitivity and specificity for MDCT were 58% and 97%, respectively. At a threshold of ∼≥20% stenosis sensitivity became >98%. All stent associated complications [fracture (4), vascular narrowings (11)] were diagnosed by MDCT. As the stent diameter increased, there was significantly reduced variability between MDCT and DA for in‐stent stenosis (P < .0001). Conclusion: In small children, MDCT is a feasible and promising method for assessing stent associated complications in the treatment of CHD. Cardiac surgeons and interventional cardiologists might rely on this imaging modality to plan specific interventions more precisely and to assess the results upon follow up.

Computed tomography correlates with improvement with ivacaftor in cystic fibrosis patients with G551D mutation

BACKGROUND Ivacaftor corrects the cystic fibrosis transmembrane conductance regulator (CFTR) gating defect associated with G551D mutation and is quickly becoming an important treatment in patients with cystic fibrosis (CF) due to this genetic mutation. METHODS A single-center study was performed in CF patients receiving ivacaftor to evaluate the usefulness of high resolution computed tomography (HRCT) of the chest as a way to gauge response to ivacaftor therapy. RESULTS Ten patients with CF were enrolled for at least one year before and after starting ivacaftor. At time of enrollment, mean age was 20.9 ± 10.8 (range 10-44) years. There were significant improvements from baseline to 6 months in mean %FVC (93 ± 16 to 99 ± 16) and %FEV1 (79 ± 26 to 87 ± 28) but reverted to baseline at one year. Mean sweat chloride levels decreased significantly from baseline to one year. Mean weight and BMI improved at 6 months. Weight continued to improve with stabilization of BMI at one year. Chest HRCT showed significant improvement at one year in mean modified Brody scores for bronchiectasis, mucous plugging, airway wall thickness, and total Brody scores. Elevated bronchiectasis and airway wall thickness scores correlated significantly with lower %FEV1, while higher airway wall thickness and mucus plugging scores correlated with more pulmonary exacerbations requiring IV and oral antibiotics respectively. CONCLUSIONS Based on our findings, HRCT imaging is a useful tool in monitoring response to ivacaftor therapy that corrects the gating defect associated with the G551D-CFTR mutation.

Usefulness of multidetector CT imaging to assess vascular stents in children with congenital heart disease: an in vivo and in vitro study.

Objective: To evaluate varying CT settings to visualize pediatric vascular stents in comparison to digital angiography (DA). Background: There is a great clinical interest in substituting noninvasive methods to follow up children with congenital heart disease after interventional treatment. Materials and Methods: CT studies in small children with transcatheter placed stents were reviewed, retrospectively. Furthermore, eight stents were implanted in tubes and partially obstructed. CT exams were performed on varying scanners (4 up to 64 slices) with corresponding tube settings. The effects of dose on image quality were evaluated regarding stent size, strut thickness, and in‐stent stenoses in comparison to DA. Results: Fourteen children with 28 implanted stents were identified. Significant differences between higher and lower radiation settings were not found, corresponding with the phantom, where moderate tube setting showed the best results. In vitro, there was an improvement with increasing number of detector rows, which resulted in a decrease of stent strut overestimation (295% down to 201%; P < 0.0001) and a better agreement with DA measurements for mild (78% up to 91%; P = 0.003) and moderate in‐stent stenoses (80% up to 99%; P = 0.0001). Conclusion: Higher radiation exposure settings did not improve image quality, suggesting that the exams could be performed at a lower radiation dose.

Duodenum inversum mimicking mesenteric artery syndrome

Background. Duodenum inversum is an often unrecognized anomaly of duodenal rotation/fixation at upper gastrointestinal (UGI) contrast study because the duodenojejunal junction appears normally located. Objective. This anomaly is important to diagnose because it may result in obstructive gastrointestinal symptoms. Conclusion. We describe a case of duodenum inversum mimicking superior mesenteric artery (SMA) syndrome that improved after surgical therapy.

Preamputation MR imaging in meningococcemia and comparison to conventional arteriography

Abstract Meningococcemia is a life-threatening infection which produces purpura fulminans and extremity gangrene in its most severe form. In patients with gangrene, amputation is usually necessary. The amputations frequently need revision as ischemic changes in the underlying soft tissues and bone are difficult to evaluate at the time of surgery. These ischemic changes often have non-vascular distributions and progress over time. We present two patients in whom MR imaging and MR angiography were performed prior to planned amputation. These cases demonstrate the potential utility of MR imaging in this setting, and compare the MR angiographic results to conventional arteriography in one of these patients.

Ivacaftor improves appearance of sinus disease on computerised tomography in cystic fibrosis patients with G551D mutation

Most patients with Cystic fibrosis (CF) have chronic sinus disease which may require multiple sinus surgeries and antibiotic courses. Ivacaftor can improve lung function, lower sweat chloride levels and improve weight by targeting the primary defect, a faulty gene and its protein product, cystic fibrosis transmembrane conductance regulator (CFTR) in patients with the G551D mutation. Its role in improving sinus disease has not been evaluated.

Image Analysis for Cystic Fibrosis: Computer-Assisted Airway Wall and Vessel Measurements from Low-Dose, Limited Scan Lung CT Images

Cystic fibrosis (CF) is a life-limiting genetic disease that affects approximately 30,000 Americans. When compared to those of normal children, airways of infants and young children with CF have thicker walls and are more dilated in high-resolution computed tomographic (CT) imaging. In this study, we develop computer-assisted methods for assessment of airway and vessel dimensions from axial, limited scan CT lung images acquired at low pediatric radiation doses. Two methods (threshold- and model-based) were developed to automatically measure airway and vessel sizes for pairs identified by a user. These methods were evaluated on chest CT images from 16 pediatric patients (eight infants and eight children) with different stages of mild CF related lung disease. Results of threshold-based, corrected with regression analysis, and model-based approaches correlated well with both electronic caliper measurements made by experienced observers and spirometric measurements of lung function. While the model-based approach results correlated slightly better with the human measurements than those of the threshold method, a hybrid method, combining these two methods, resulted in the best results.

Image analysis for cystic fibrosis: Automatic lung airway wall and vessel measurement on CT images

Cystic Fibrosis (CF) is the most common lethal genetic disorder in the Caucasian population, affecting about 30,000 people in the United States. It results in inflammation, hence thickening of airway (AW) walls. It has been demonstrated that AW inflammation begins early in life producing structural AW damage. Because this damage can be present in patients who are relatively asymptomatic, lung disease can progress insidiously. High-resolution computed tomographic imaging has also shown that the AWs of infants and young children with CF have thicker walls and are more dilated than those of normal children. The purpose of this study was to develop computerized methods which allow rapid, efficient and accurate assessment of computed tomographic AW and vessel (V) dimensions from axial CT lung images. For this purpose, a full-width-half-max based automatic AW and V size measurement method was developed. The only user input required is approximate center marking of AW and V by an expert. The method was evaluated on a patient population of 4 infants and 4 children with different stages of mild CF related lung disease. This new automated method for assessing early AW disease in infants and children with CF represents a potentially useful outcome measure for future intervention trials.