Ana Maria Gaca

Radiation Doses from Small-Bowel Follow-Through and Abdominopelvic MDCT in Crohn's Disease

OBJECTIVE The purpose of our study was to compare organ and effective doses for small-bowel follow-through (SBFT) and abdominopelvic MDCT in adults with Crohns disease, to retrospectively evaluate the number of radiographic examinations performed for Crohns disease indications, and to identify those patients undergoing serial examinations to better delineate the use of radiology in the diagnosis and clinical management of Crohns disease. MATERIALS AND METHODS Using an anthropomorphic phantom and metal-oxide semiconductor field-effect transistor (MOSFET) dosimeters, specific organ doses were measured for 5 minutes of continuous fluoroscopy (kVp, 120; mA, 0.6) of each of the following: right lower quadrant, central abdomen, and pelvis. Effective doses were determined based on International Commission on Radiological Protection (ICRP) 60 weighting factors. Organ and effective doses were determined for abdominal and pelvic 16-MDCT: detector configuration, 16 x 0.625 mm; pitch, 1.75; 17.5 mm per rotation; rotation time, 0.5 second; 140 kVp; 340 mA. Electronic records were reviewed to determine the number of patients imaged for Crohns disease indications and the number of studies per patient. RESULTS The highest fluoroscopic organ doses were as follows: in the right lower quadrant, right kidney (0.78 cGy) and marrow (0.66 cGy); in the central abdomen, kidneys (1.5 and 1.6 cGy) and marrow (0.76 cGy); and in the pelvis, marrow (0.67-0.95 cGy). Effective doses for the right lower quadrant, central abdomen, and pelvis were 1.37, 2.02, and 3.83 mSv, respectively. For MDCT, the highest organ doses were to the liver (2.95-3.33 cGy). The effective dose for abdominopelvic MDCT was 16.1 mSv. Three hundred seventy-three patients underwent imaging for Crohns disease. The average number of SBFT and CT examinations was 1.8 and 2.3, respectively. Thirty-four (9%) of 373 patients underwent more than five CT examinations and 11 (3%) had more than 10. CONCLUSION Organ and effective doses are up to five times higher with MDCT than with SBFT. Crohns disease is more frequently imaged with CT. For a subset of patients who undergo numerous CT examinations, efforts should be made to minimize the number of CT examinations, decrease the CT dose, or consider MR enterography.

Repair of Congenital Heart Disease: A Primer–Part 1

Advances in the surgical management of congenital heart disease have led to enhanced patient survival and quality of life. Improvements in technology in computed tomography and magnetic resonance imaging have resulted in increasing use of cross-sectional imaging in these patients. Perioperative care in these patients requires that radiologists have an understanding of the surgical treatment and the resultant postoperative anatomy. Because many of these patients with treated congenital heart disease are being followed into the 4th and 5th decades of life, this is information that will fall within the domain of the radiologist who deals with adults. This review, which is presented in two parts, covers the major surgical procedures used for the treatment of congenital heart disease, and will be presented in two parts. In part 1, median sternotomy and its complications, palliative procedures, and complex repairs are discussed.

Evaluation of Wedging of Lower Thoracic and Upper Lumbar Vertebral Bodies in the Pediatric Population

OBJECTIVE Anterior wedging of thoracolumbar vertebral bodies is often seen in children. The purpose of our study was to show whether mild anterior wedging of pediatric thoracolumbar junction vertebral bodies can be seen as a normal variant, rather than as the sequela of trauma. MATERIALS AND METHODS A retrospective review was performed of pediatric abdomen and pelvis CT performed between January 2004 and March 2006, excluding children at high risk for compression fractures. Twenty CT studies were randomly selected for each of five arbitrary age groups: < 3, 4-7, 8-11, 12-14, and 15-17 years (100 total CT studies). Using sagittal reformations, anterior and posterior heights of all T10-L3 vertebral bodies were measured to determine anterior-to-posterior vertebral body height ratio (A:P ratio). Inter- and intraobserver agreement was determined. The lower limit of normal (lower fifth percentile of the distribution) was estimated using quantile regression. RESULTS A:P ratio at the thoracolumbar junction was greater than 0.893 in 95% of children. There was no statistically significant correlation between age and the A:P ratio. There was strong intra- and interobserver agreement. CONCLUSION From T10 through L3, 95% of children have an A:P ratio greater than 0.893. This suggests that an A:P ratio less than 0.893 should raise the possibility of vertebral body injury. Because age was not statistically significant with respect to the A:P ratio, this value can be used across all pediatric age groups.

Pediatric MDCT: Towards Assessing the Diagnostic Influence of Dose Reduction on the Detection of Small Lung Nodules

RATIONALE AND OBJECTIVES The purpose of this study was to evaluate the effect of reduced tube current (dose) on lung nodule detection in pediatric multidetector array computed tomography (MDCT). MATERIALS AND METHODS The study included normal clinical chest MDCT images of 13 patients (aged 1-7 years) scanned at tube currents of 70 to 180 mA. Calibrated noise addition software was used to simulate cases as they would have been acquired at 70 mA (the lowest original tube current), 35 mA (50% reduction), and 17.5 mA (75% reduction). Using a validated nodule simulation technique, small lung nodules of 3 to 5 mm in diameter were inserted into the cases, which were then randomized and rated independently by three experienced pediatric radiologists for nodule presence on a continuous scale ranging from zero (definitely absent) to 100 (definitely present). The observer data were analyzed to assess the influence of dose on detection accuracy using the Dorfman-Berbaum-Mets method for multiobserver, multitreatment receiver-operating characteristic (ROC) analysis and the Williams trend test. RESULTS The areas under the ROC curves were 0.95, 0.91, and 0.92 at 70, 35, and 17.5 mA, respectively, with standard errors of 0.02 and interobserver variability of 0.02. The Dorfman-Berbaum-Mets method and the Williams trend test yielded P values for the effect of dose of .09 and .05, respectively. CONCLUSION Tube current (dose) has a weak effect on the detection accuracy of small lung nodules in pediatric MDCT. The effect on detection accuracy of a 75% dose reduction was comparable to interobserver variability, suggesting a potential for dose reduction.

Lung nodule detection in pediatric chest CT: Quantitative relationship between image quality and radiologist performance

PURPOSE To determine the quantitative relationship between image quality and radiologist performance in detecting small lung nodules in pediatric CT. METHODS The study included clinical chest CT images of 30 pediatric patients (0-16 years) scanned at tube currents of 55-180 mA. Calibrated noise addition software was used to simulate cases at three nominal mA settings: 70, 35, and 17.5 mA, resulting in quantum noise of 7-32 Hounsfield Unit (HU). Using a validated nodule simulation technique, lung nodules with diameters of 3-5 mm and peak contrasts of 200-500 HU were inserted into the cases, which were then randomized and rated independently by four experienced pediatric radiologists for nodule presence on a continuous scale from 0 (definitely absent) to 100 (definitely present). The receiver operating characteristic (ROC) data were analyzed to quantify the relationship between diagnostic accuracy (area under the ROC curve, AUC) and image quality (the product of nodule peak contrast and displayed diameter to noise ratio, CDNR display). RESULTS AUC increased rapidly from 0.70 to 0.87 when CDNR display increased from 60 to 130 mm, followed by a slow increase to 0.94 when CDNR display further increased to 257 mm. For the average nodule diameter (4 mm) and contrast (350 HU), AUC decreased from 0.93 to 0.71 with noise increased from 7 to 28 HU. CONCLUSIONS We quantified the relationship between image quality and the performance of radiologists in detecting lung nodules in pediatric CT. The relationship can guide CT protocol design to achieve the desired diagnostic performance at the lowest radiation dose.]

Basketball injuries in children

Basketball is a popular, worldwide sport played outdoors and indoors year-round. Patterns of injury are related to abrupt changes in the athlete’s direction, jumping, contact between athletes, the hard playing surface and paucity of protective equipment. Intensity of play and training in the quest of scholarships and professional careers is believed to contribute to an increasing occurrence of injury. Radiologists’ appreciation of the breadth of injury and its relation to imaging and clinical findings should enhance the care of these children. Some of the patterns of injury are well known to radiologists but vary due to age- and size-related changes; the growing skeleton is affected by differing susceptibilities from biomechanical stresses at different sizes. Beyond screening radiographs, the accuracy of MRI and CT has improved diagnosis and treatment plans in this realm. Investigations to detect symptoms and signs in an attempt to prevent the tragedy of sudden cardiac death in basketball players may lead to MRI and CTA studies that compel radiologists to evaluate cardiac function along with myocardial and coronary artery anatomy. Worthy of mention also is the female athlete triad of disordered eating, amenorrhea, and osteoporosis that is observed in some young women participating in this and other sports.

Successful treatment of pediatric histiocytic sarcoma using abbreviated high-risk leukemia chemotherapy

Histiocytic sarcoma (HS) is a malignant tumor composed of proliferating cells of histiocytic origin. True HS is exceedingly rare, particularly in pediatric patients. These tumors are frequently aggressive, and outcome for patients with HS has traditionally been poor. There is currently no consensus on the optimal management of these tumors, with the literature consisting largely of case reports and small case series utilizing a wide variety of therapies. We describe a case of HS in an 8‐year‐old female who was successfully treated with an abbreviated leukemia chemotherapy regimen. Pediatr Blood Cancer 2014; 61:1874–1876.

The radiology perspective: needs and tools for management of life-threatening events

Studies have shown that life-threatening contrast agent reactions in adults are very rare, and even less common in children. The rarity of severe allergic reactions to contrast material challenges educators to achieve radiology resident competency in this setting. However, using a simulated anaphylactic contrast reaction paradigm, we have drawn two conclusions: (1) Residents are insufficiently prepared to recognize and manage these life-threatening events and (2) with an interactive, computer-based tool we can significantly improve resident performance in these situations. Simulation is a growing tool in medicine and allows standardized resident exposure to uncommon events in a setting that is conducive to resident education without fear of repercussions (see Ruddy and Patterson in this issue of Pediatric Radiology). More important, simulation provides a cornerstone in patient safety resident education without putting patients at risk.

Comparison of Conventional and Simulated Reduced–Tube Current MDCT for Evaluation of Suspected Appendicitis in the Pediatric Population

OBJECTIVE The purpose of this study was to compare CT with conventional and simulated reduced-tube current in the evaluation for acute appendicitis in children. MATERIALS AND METHODS Validated noise-addition (tube current-reduction) software was used to create 50% and 75% tube current reductions in 60 CT examinations performed for suspected appendicitis, resulting in 180 image sets. Three blinded pediatric radiologists scored the randomized studies for the following factors: presence of the normal appendix or appendicitis (5-point scale; 1=definitely absent and 5=definitely present), presence of alternate diagnoses, and overall image quality (1=nondiagnostic and 5=excellent). Truth was defined by the interpretation of the conventional examination. RESULTS For conventional examinations, the total number of reviews (60 cases×3 readers=180) in which the normal appendix was identified was 120 of 180 (66.7%), compared with 108 of 180 (60%) in the 50% (p=0.19) and 91 of 180 (50.6%) in the 75% (p=0.002) tube current-reduction groups. Appendicitis was identified in a total of 39 of 180 (21.7%), 38 of 180 (21.1%), and 37 of 180 (20.6%) examinations, respectively (p>0.05). This translates to sensitivities of 97% and 95% for the 50% and 75% tube current-reduction groups, respectively. Alternate diagnoses were detected in 14%, 16%, and 13% of scans, respectively. Compared with conventional-tube current examinations, reader confidence and assessment of image quality were significantly decreased for both tube current-reduction groups. CONCLUSION Simulated tube current-reduction technology provides for systematic evaluation of diagnostic thresholds. Application of this technology in the setting of suspected appendicitis shows that tube current can be reduced by at least 50% without significantly affecting diagnostic quality, despite a decrease in reader confidence and assessment of image quality.

MLL duplication in a pediatric patient with B-cell lymphoblastic lymphoma.

Lymphoblastic lymphoma is the second most common type of non-Hodgkin lymphoma seen in children. Approximately, 90% of lymphoblastic lymphomas arise from T cells, with the remaining 10% being B-cell-lineage derived. Although T-cell lymphoblastic lymphoma most frequently occurs in the anterior mediastinum (thymus), B-cell lymphoblastic lymphoma (B-LBL) predominates in extranodal sites such as skin and bone. Here, we describe a pediatric B-LBL patient who presented with extensive abdominal involvement and whose lymphoma cells displayed segmental duplication of the mixed lineage leukemia (MLL) gene. MLL duplication/amplification has been described primarily in acute myeloid leukemia and myelodysplastic syndrome with no published reports of discrete MLL duplication/amplification events in B-LBL. The MLL gene duplication noted in this case may represent a novel mechanism for tumorigenesis in B-LBL.