Kristen B. Thomas

Optimal Tube Potential for Radiation Dose Reduction in Pediatric CT: Principles, Clinical Implementations, and Pitfalls

In addition to existing strategies for reducing radiation dose in computed tomographic (CT) examinations, such as the use of automatic exposure control, use of the optimal tube potential also may help improve image quality or reduce radiation dose in pediatric CT examinations. The main benefit of the use of a lower tube potential is that it provides improved contrast enhancement, a characteristic that may compensate for the increase in noise that often occurs at lower tube potentials and that may allow radiation dose to be substantially reduced. However, selecting an appropriate tube potential and determining how much to reduce radiation dose depend on the patients size and the diagnostic task being performed. The power limits of the CT scanner and the desired scanning speed also must be considered. The use of a lower tube potential and the amount by which to reduce radiation dose must be carefully evaluated for each type of examination to achieve an optimal tradeoff between contrast, noise, artifacts, and scanning speed.

The "Good" Dean's Letter

Purpose To determine whether a correlation exists between the term “good” on the summative, comparative assessment of a students Medical Student Performance Evaluation (MSPE) and his or her actual performance in medical school. Method The authors reviewed the MSPEs submitted to three residency programs to determine the presence of the term “good” in either the summary paragraph or the appendices. Next, they noted, for institutions using “good,” the percentile rankings of those students who received “good” as a descriptor. To examine the consistency among institutions regarding the percentile ranking denoted by “good,” they dichotomized the data into students below and above the bottom 25th percentile. They analyzed the data using a nonparametric test because of their nonnormal distribution. Results The authors collected MSPEs from 122 of the 125 Liaison Committee on Medical Education–accredited medical schools that were graduating students in 2008. Of these 122 institutions, 34 (28%) used the term “good.” All 34 institutions used the term to characterize students in the bottom 50% of the graduating class. The authors found a significant difference in the percentile ranking of students described as “good” between institutions using it to describe the bottom 25% and institutions using the term to describe those in the 25th to 50th percentiles (median ranking of 12.5% versus 30%, P < .0001). Conclusions Overall, the term “good” in the MSPE describes students in the bottom 50% of the class; therefore, the term “good,” as used to describe performance in medical school, consistently indicates below-average performance.

Deficiency of interleukin-1-receptor antagonist syndrome: a rare auto-inflammatory condition that mimics multiple classic radiographic findings.

Deficiency of interleukin-1-receptor antagonist (DIRA) syndrome is a newly identified inflammatory disease of the skeleton and appendicular soft tissues presenting in early infancy that has yet to be reported in the radiology literature. The radiological manifestations of DIRA syndrome include multifocal osteitis of the ribs and long bones, heterotopic ossification and periarticular soft-tissue swelling. Thus, the pediatric radiologist should be made aware of this novel disease because its radiographic findings can mimic multiple other disease entities. With knowledge of the unique clinical presentation of DIRA syndrome and its multiple radiographic manifestations, the pediatric radiologist may be the first to suggest the correct diagnosis.

Radiation Dose Reduction in Pediatric Body CT Using Iterative Reconstruction and a Novel Image-Based Denoising Method

OBJECTIVE The objective of this study was to evaluate the radiation dose reduction potential of a novel image-based denoising technique in pediatric abdominopelvic and chest CT examinations and compare it with a commercial iterative reconstruction method. MATERIALS AND METHODS Data were retrospectively collected from 50 (25 abdominopelvic and 25 chest) clinically indicated pediatric CT examinations. For each examination, a validated noise-insertion tool was used to simulate half-dose data, which were reconstructed using filtered back-projection (FBP) and sinogram-affirmed iterative reconstruction (SAFIRE) methods. A newly developed denoising technique, adaptive nonlocal means (aNLM), was also applied. For each of the 50 patients, three pediatric radiologists evaluated four datasets: full dose plus FBP, half dose plus FBP, half dose plus SAFIRE, and half dose plus aNLM. For each examination, the order of preference for the four datasets was ranked. The organ-specific diagnosis and diagnostic confidence for five primary organs were recorded. RESULTS The mean (± SD) volume CT dose index for the full-dose scan was 5.3 ± 2.1 mGy for abdominopelvic examinations and 2.4 ± 1.1 mGy for chest examinations. For abdominopelvic examinations, there was no statistically significant difference between the half dose plus aNLM dataset and the full dose plus FBP dataset (3.6 ± 1.0 vs 3.6 ± 0.9, respectively; p = 0.52), and aNLM performed better than SAFIRE. For chest examinations, there was no statistically significant difference between the half dose plus SAFIRE and the full dose plus FBP (4.1 ± 0.6 vs 4.2 ± 0.6, respectively; p = 0.67), and SAFIRE performed better than aNLM. For all organs, there was more than 85% agreement in organ-specific diagnosis among the three half-dose configurations and the full dose plus FBP configuration. CONCLUSION Although a novel image-based denoising technique performed better than a commercial iterative reconstruction method in pediatric abdominopelvic CT examinations, it performed worse in pediatric chest CT examinations. A 50% dose reduction can be achieved while maintaining diagnostic quality.

Trends in CT utilization for pediatric fall patients in US emergency departments

RATIONALE AND OBJECTIVES Falls are a common cause of emergency department (ED) visits in the United States. We evaluated trends in computed tomography (CT) utilization for pediatric fall victims in the United States from 2001 to 2010. MATERIALS AND METHODS Using the National Hospital Ambulatory Medical Care Survey from 2001 to 2010, we identified all visits of pediatric (aged <18 years) patients presenting to EDs after falls. This database surveys approximately 500 EDs per year for 4 weeks providing national estimates on ED resource utilization and outcomes. We studied trends in CT utilization and proportion of visits with life-threatening conditions after falls. We also studied the association between CT utilization rates and demographic characteristics and admission status. RESULTS A total of 9763 unweighted observations for a total of 32,432,686 pediatric fall patients were seen in US EDs from 2001 to 2010. The proportion of pediatric fall patients receiving CT increased from 5.3% in 2001 to a peak of 16.6% in 2009 and decreased to 11.3% in 2010, whereas the proportion of pediatric fall patients with life-threatening conditions fluctuated between 1.2% and 3.3% during this period. In multivariate logistic regression analysis, each increasing year was independently associated with CT utilization (odds ratio [OR], 1.15; 95% confidence interval [CI], 1.14-1.16). Patients aged 0-1 years had higher odds of CT utilization than patients aged 13-17 years (OR, 2.27; 95% CI, 2.26-2.27). CONCLUSIONS There was a twofold increase in CT utilization among pediatric fall visits from 2001 to 2010. When controlling for demographic and clinical variables, increasing year was independently associated with CT utilization. These findings suggest that CT may be overutilized among pediatric fall patients.

Chronic tibial nonunion in a Rothmund–Thomson syndrome patient

Rothmund–Thomson syndrome (RTS) is an autosomal recessive disorder caused by biallelic mutations in RECQL4, a helicase involved with chromosomal instability and DNA repair. Patients typically present with a poikilodermatous facial rash, photosensitivity, congenital bony abnormalities, short stature, and have a predilection for osteosarcoma and cutaneous malignancies. We present a 34‐year‐old male RTS patient, previously diagnosed with osteosarcoma of the right forearm which was successfully treated with resection and chemotherapy, who has had multiple tibial fractures and has suffered from chronic nonunion of the proximal tibias bilaterally for greater than 9 years. The patient subsequently developed generalized lower extremity osteopenia with normal calcium homeostasis and calcitriol levels. As the RTS population continues to reach greater ages we must be mindful of other health concerns that may develop. Bone health is one considerable concern with a large portion of patients having congenital bony abnormalities and many receiving chemotherapy for osteosarcoma. We conclude that screening for bone health and supplementation with calcium and vitamin D may be warranted in RTS patients with a history of fractures and osteosarcoma treatment.

A novel sclerosing skeletal dysplasia with mixed sclerosing bone dysplasia, characteristic syndromic features, and clinical and radiographic evidence of male–male transmission†‡

We report on a father and his 4‐year‐old son sharing a characteristic dysmorphic facial phenotype (including hyperteleroism, prominent forehead, and wide nasal bridge), macrocephaly, hearing loss, palatal clefting, developmental delay, hypotonia and bony abnormalities including marked cranial sclerosis and sclerosis of the ribs and long bones, which evolved in severity in the son between the ages of 2 and 4 years. The fathers radiographs also showed prominent coarse striations, patchy metaphyseal sclerotic plaques, markedly increased bone density and cortical thickening of long bones, and significant degenerative changes in the thoracic spine. The son has an additional history of sleep apnea resulting from multi‐level airway obstruction that includes adenoid hypertrophy, lingual tonsil hypertrophy, subglottic stenosis, and supra‐arytenoid tissue consistent with laryngomalacia and tracheomalacia. The clinical, radiographic, and genetic findings in father and son are consistent with a sclerosing skeletal dysplasia syndrome with similarities to mixed sclerosing bone dysplasia (MSBD) including metaphyseal plaques, osteopathia striata, and cranial sclerosis (OS–CS). This family may represent one of the first descriptions of familial inheritance and evolving phenotype in MSBD. The evidence for male–male transmission would support the existence of an autosomal mechanism of inheritance for a novel form of MSBD with characteristic syndromic features.

Concurrent acute appendicitis and ileocolic intussusception in a 1-year-old child

Intussusception and acute appendicitis are part of a differential diagnosis for acute abdominal pain and vomiting in the pediatric population. We describe a unique case combining appendiceal intussusception with concurrent acute appendicitis, or “appendi-sception.” A 1-year-old boy presented with 1 day of fussiness, vomiting, and red, gelatinous stool. Initial diagnosis on ultrasound was a routine ileocolic intussusception with nonvisualization of the appendix. However, after a failed air enema decompression, the patient was taken to the operating room where the appendix was discovered to be inflamed within the intussusceptum. This case is unique as few cases of both conditions occurring simultaneously have been previously described. It is important for radiologists to be aware of this combination of diagnoses as both require urgent evaluation and prompt treatment.

Ultrasonography and the American Thyroid Association Ultrasound-Based Risk Stratification Tool: Utility in Pediatric and Adolescent Thyroid Nodules

Background: Pediatric thyroid nodules are more likely to be malignant compared to those in adults and may have different concerning ultrasound (US) features. Recent adult guidelines stratify malignancy risk by US features. Our aim is to (1) describe and confirm US features that predict pediatric malignancy, and (2) apply the Adult American Thyroid Association (ATA) Risk Stratification Guidelines to a large pediatric cohort. Methods: We identified 112 children with 145 thyroid nodules from 1996 to 2015. Two blinded pediatric radiologists independently read all US images, described multiple features, and reported their overall impression: benign, indeterminate, or malignant. Each nodule was assigned an ATA risk stratification category. Radiologists’ impressions and ATA risk stratification were compared to histology and cytology results. Results: Multiple US features including a solid composition, presence of microcalcifications, irregular margins, increased blood flow, and hypoechogenicity were associated with increased odds of malignancy. ATA risk stratification correlated with the radiologists’ overall impression (p < 0.001). The sensitivity for detecting malignancy was comparable between both ATA stratification (91%) and the radiologists’ overall impression (90%). The specificity of the radiologists’ malignant overall impression (80%) was better compared to the ATA high risk stratification (54%). Conclusions: At our institution, pediatric radiologists’ overall impressions had similar sensitivity but better specificity for detecting malignancy than the ATA risk stratification tool by our convention. However, neither US-based methods perfectly discriminated benign from malignant nodules, supporting the continued need for fine needle aspiration for suspicious nodules. Further work is needed to develop an US-based scoring system specific to pediatric patients.

Diagnostic Accuracy of the McGill Thyroid Nodule Score in Pediatric Patients

Thyroid cancer is the most common paediatric endocrine cancer; accurate diagnosis and prompt management of paediatric thyroid nodules is critical. The McGill Thyroid Nodule Score (MTNS), based upon clinical, ultrasound (US) and cytology criteria, has recently been modified and studied in a pilot paediatric group with good results. We aim to describe the diagnostic accuracy of the paediatric modified MTNS (PMTNS) in a large paediatric cohort.