Lane F. Donnelly

Lessons from history

related to radiation exposure from the historic perspective. The history will be discussed in the context of how it relates to radiation dose in CT as compared to radiation exposure at the time of the discovery of X-rays in the beginning of the last century. This will be followed by the background behind the articles that came out in the February 2001 AJR, and the final portion of the lecture will introduce practical changes that pediatric radiologists can make to decrease radiation dose in their departments today. Looking back, I think it is interesting if you note some of the mistakes that were made relative to radiation exposure in the beginning of last century and compare this to what is going on now. There are many parallels. In both scenarios, there was the introduction of new technology, dramatic overuse of that technology, unforeseen dangers associated with the technology and a delay in refining the techniques, in implementing safety and protection issues. Within a couple of months after the discovery of X-rays by Roentgen in 1895, the undesired effects of X-rays were noticed: dermatitis, hair loss, etc. (Fig. 1). Many of these effects were thought to be temporary and safety precautions were largely ignored. The article written by a man named Hawks illustrates what was happening during this period. Hawks was a radiology technologist employed by General Electric. His job was to demonstrate X-rays for shoppers at Bloomingdale’s. He would often use his own hand and face to show the customers what his bones looked like behind the X-ray. The article described that he developed a very deep sunburn, hair loss, bloodshot eyes, and vision impairment related to his X-ray exposure. Unfortunately, the article also described that all of these symptoms were temporary and at the time of the publication, Hawks had actually returned to work demonstrating X-ray equipment. We have all seen historic photographs of the undesired effects of radiation associated with its inappropriate use. Many of these illustrations can be seen in Eisenberg’s Illustrated History of Radiography. Photographs demonstrate some of the early pioneers of radiography creating X-rays with a complete lack of safety precautions (Fig. 2). Images of the same radiology pioneers are available demonstrating changes in their hands over time with multiple fingers being amputated because of radiation-induced carcinoma (Fig. 3). There was a very slow response in regards to safety precautions in radiography. People questioned the dangers of X-rays and the actual true source of these complications. There was a marked resistance to the implementation of safety precautions. An interesting article by W. Rawlins was published in 1901. Rawlins took a number of guinea pigs and exposed them to Xrays for 2 h a day with all the guinea pigs dying between 8 and 10 days. His conclusion and title of his article was ‘‘X-rays Can Kill.’’ This was the first time that this had actually been suggested. Rawlins had a number of insightful recommendations for radiation safety: (1) put lead housing around the X-ray tubes so X-rays were only passing in the intended direction, (2) X-ray operators should wear radio-opaque glasses, and (3) that the region of interest should be columnated so that adjacent areas were shielded from unnecessary radiation exposure. In the following meetings of the American Roentgen Ray Society, there were heated discussions about his suggestions. A response from that meeting was published in the same journal in which Rawlins’ work SESS ION I I I : THE ROLE OF THE PED IATR IC RADIOLOGI ST IN DOSE REDUCT ION

Effect of increasing depth of dexmedetomidine and propofol anesthesia on upper airway morphology in children and adolescents with obstructive sleep apnea

STUDY OBJECTIVE To examine the dose-response effects of dexmedetomidine (DEX) and propofol (PROP) on airway morphology in children and adolescents with a history of obstructive sleep apnea (OSA). DESIGN Prospective, single-blinded, controlled comparative study. SETTING University-affiliated teaching hospital. PATIENTS 60 patients with a history of OSA who presented for a magnetic resonance imaging (MRI) sleep study. INTERVENTIONS Patients were randomized to two equal groups (DEX or PROP). Magnetic resonance images of the airway were obtained during low (1 μg/kg/hr) and high (3 μg/kg/hr) doses of DEX, or low (100 μg/kg/m) and high (200 μg/kg/m) doses of PROP, based on group assignment. MEASUREMENTS The airway anteroposterior (AP) diameter, transverse diameter, and sectional areas were measured at the level of the nasopharyngeal airway and retroglossal airway. The influence of the two drugs and OSA severity, as determined by polysomnography, on airway dimensions was examined using mixed-effects analysis of covariance models. MAIN RESULTS Upper airway morphology was completed in 45 patients. Most airway measurements showed statistically nonsignificant associations with increasing doses of PROP and DEX. As the dosage increased, average airway dimensions were typically unchanged or slightly increased with DEX compared with airway dimensions that were unchanged or slightly decreased with PROP. An airway intervention was required in three children (11%) in the DEX group and 7 children (23%) in the PROP group (P = NS). CONCLUSIONS Both agents provided an acceptable level of anesthesia for MRI sleep studies in patients with OSA, with statistically nonsignificant changes in airway dimensions.

MRI findings of lipoma arborescens of the knee in a child: Case report

Lipoma arborescens is an intraarticular lesion characterized by a frond-like mass of mature fat cells, usually involving the suprapatellar bursa. It is a rare lesion in adults and extremely rare in children. Because of the fatty nature of the lesion, the MRI findings of lipoma arborescens are specific. We present the MRI findings of lipoma arborescens of the knee in a 9-year-old girl.

Comparison between morphologic changes seen on high-resolution CT and regional pulmonary perfusion seen on SPECT in patients with cystic fibrosis

Objective. To evaluate the relationship between morphologic findings seen on high-resolution computed tomography (HRCT) of the lung and regional lung perfusion depicted on single photon-emission computed tomography (SPECT) pulmonary perfusion imaging in patients with cystic fibrosis. Materials and methods. Ten HRCT and 10 technetium-99 m macroaggregated albumin SPECT pulmonary perfusion imaging studies were performed on eight young adult patients who were considered to be clinically well and have mild to moderate cystic fibrosis. HRCT scans of the chest were evaluated using a CT scoring system which included grading of bronchiectasis, peribronchial thickening, hyperlucency, bullae, collapse/consolidation, and mucus plugging. Each lung was divided into six anatomic zones which were independently scored. A lung perfusion score (between 0 and 100), reflecting the percentage of compromised lung, was estimated for each zone. Axial lung perfusion SPECT images were matched anatomically to HRCT images. Lung function was considered compromised when the counts per pixel were less than 25 % of the count level seen in an area of the same patients lung which was judged to be normal. Results. There was a statistically significant relationship (P = 0.0001) between HRCT total scores and SPECT lung perfusion scores as well as between hyperlucency scores by HRCT and the SPECT lung perfusion scores. However, the HRCT score was a poor predictor of the lung perfusion score in zones with intermediate HRCT scores, which constituted 106 of 120 zones. Conclusion. Morphologic changes depicted by HRCT correlate with decreased lung pefusion on SPECT. However, HRCT changes accurately predict regional lung function only in the most normal and severely diseased lung zones.

Data acquisition for pediatric CT angiography: problems and solutions.

Abstract With appropriate attention to the technical aspects, excellent CT angiography can be obtained even in young infants. In this article, we will present the problems inherent with pediatric CT angiography and offer solutions that minimize or eliminate these difficulties. In addition, a literature review of specific pediatric applications is provided.

Marked acute tissue swelling following percutaneous sclerosis of low-flow vascular malformations: a predictor of both prolonged recovery and therapeutic effect

Purpose. To evaluate the significance of marked, acute swelling in patients after percutaneous sclerosis of low-flow vascular malformations, as a predictor of both prolonged recovery and likelihood of therapeutic effect.¶Materials and methods. In 22 patients who underwent percutaneous ethanol sclerosis of low-flow vascular malformations, we compared the incidence of prolonged recovery and lasting therapeutic effect between those patients with and without marked soft-tissue swelling following the procedure.¶Results. Five patients exhibited marked swelling after sclerosis. Four of these five had causes of prolonged recovery. These four recovered and all five eventually had marked therapeutic effect. Seventeen patients did not meet criteria for severe swelling. Only one of these patients had prolonged recovery. Eighteen of the 22 total patients had therapeutic effect. All 4 of the 22 total patients who had no therapeutic effect were in the group without marked swelling.¶Conclusions. Marked soft-tissue swelling, which occurs after percutaneous sclerosis of vascular malformations, is both a predictor of prolonged recovery and high likelihood of therapeutic effect.

Transhepatic catheterization using ultrasound-guided access.

The efficacy and safety of ultrasound guidance to obtain transhepatic access for cardiac catheterization were investigated in this study. The transhepatic route for access to perform cardiac catheterization has become an acceptable alternative when conventional routes of access have failed. However, the use of ultrasound to guide transhepatic access has not been reported in the literature. We performed a retrospective chart review. Patient characteristics, indications for catheterization, procedures performed, and complications were recorded. All patients who underwent transhepatic cardiac catheterization at Duke University Medical Center were included in thids study. Eight patients underwent 12 catheterizations. The median age was 5.3 years (range, 9 months to 13 years) and median weight 18.7 kg (range, 7.1–44.8 kg). Seven catheterizations were diagnostic and 5 were interventional. There were no complications. Transhepatic access with ultrasound guidance is a safe and effective option for obtaining venous access for cardiac catheterization.

Is echocardiography or magnetic resonance imaging superior for precoarctation angioplasty evaluation

We compared the dimensions of the aorta obtained by two-dimensional transthoracic echocardiography (echo) (median, 2.5 mo preangioplasty) and magnetic resonance imaging (MRI) (median, 4.2 mo preangioplasty) to those obtained by angiography (cath) in 13 patients (age, 7.7 +/- 1.6 yr; mean +/- SEM) who underwent evaluation for coarctation balloon angioplasty between April 1993-January 1996. Echo measurements were obtained from the suprasternal and subcostal sagittal planes, MRI measurements from axial and sagittal oblique views, and cath measurements from the straight lateral or oblique views. Measurements of the diameters of the aortic isthmus, coarctation, descending aorta at the diaphragm, and isthmus length were made by all three modalities. Presence of aorto-aortic collaterals was determined, and the coarctation length was delineated. Investigators were blinded to other measurement data prior to statistical analysis. Data analysis by repeated analysis of variance (ANOVA) and Student-Newman-Keuls testing revealed no statistically significant difference between systolic pressure gradient by clinical examination (32.2 +/- 5.9 mm Hg), peak instantaneous Doppler evaluation (37.5 +/- 2.9 mm Hg), or preangioplasty systolic pressure gradient (32.1 +/- 3.3 mm Hg). With the exception of measurements of the descending aorta (echo, 11.7 +/- 0.9 mm vs. MRI, 13.3 +/- 0.8 mm vs. cath, 14.0 +/- 1.3 mm; P = 0.04), there was no statistically significant difference in dimensions of the aortic isthmus (9.2 +/- 0.6 mm vs. 10.5 +/- 0.9 mm vs. 10.8 +/- 0.9 mm), coarctation site diameter (4.8 +/- 0.6 mm vs. 5.6 +/- 0.9 mm vs. 5.3 +/- 0.8 mm), or isthmus length (12.4 +/- 2.1 mm vs. 12.1 +/- 2.2 mm vs. 10.9 +/- 1.7 mm). The correlation coefficients derived from comparisons of MRI vs. cath to echo vs. cath were similar for all dimensions except for isthmus length (P < 0.01). MRI demonstrated aorto-aortic collaterals more frequently than echo, while echocardiography better demonstrated cardiac function and intracardiac anomalies. Both modalities detected the single patient with a long segment coarctation. We conclude that echocardiography and MRI provide similar definition of the coarcted thoracic aorta, and either test may be individually advantageous in specific clinical situations.

Purulent pericarditis presenting as acute abdomen in children: Abdominal imaging findings

Purulent pericarditis is rapidly fatal if untreated [1,2]. With increased development of bacterial resistance to antibiotics, severe bacterial infections in children are becoming more frequent [3,4]. We report two children with purulent pericarditis who presented in a 1-month period for evaluation of acute abdominal distention and signs of sepsis. In both, one evaluated with computed tomography (CT) and one with ultrasound, abdominal findings included periportal edema, gallbladder wall thickening, and ascites secondary to right heart failure from cardiac tamponade. Radiologists should be aware that children with purulent pericarditis may have a normal heart size on radiographs, present with acute abdominal symptoms, and demonstrate findings of right sided heart failure on abdominal imaging.

Chronic avulsive injuries of childhood

Abstract Children and adolescents are prone to avulsive injuries related to a combination of their propensity for great strength, ability to sustain extreme levels of activity, and immature growing apophyses. Appropriate interpretation of imaging studies showing chronic avulsive injuries is essential so that the irregularity and periostitis that can be associated with chronic avulsions is not misinterpreted as probable malignancy. This article reviews the chronic avulsive injuries of childhood.