Owen J. O'Connor

Development of Low-Dose Protocols for Thin-Section CT Assessment of Cystic Fibrosis in Pediatric Patients

PURPOSE To develop low-dose thin-section computed tomographic (CT) protocols for assessment of cystic fibrosis (CF) in pediatric patients and determine the clinical usefulness thereof compared with chest radiography. MATERIALS AND METHODS After institutional review board approval and informed consent from patients or guardians were obtained, 14 patients with CF and 11 patients without CF (16 male, nine female; mean age, 12.6 years ± 5.4 [standard deviation]; range, 3.5-25 years) who underwent imaging for clinical reasons underwent low-dose thin-section CT. Sections 1 mm thick (protocol A) were used in 10 patients, and sections 0.5 mm thick (protocol B) were used in 15 patients at six levels at 120 kVp and 30-50 mA. Image quality and diagnostic acceptability were scored qualitatively and quantitatively by two radiologists who also quantified disease severity at thin-section CT and chest radiography. Effective doses were calculated by using a CT dosimetry calculator. RESULTS Low-dose thin-section CT was performed with mean effective doses of 0.19 mSv ± 0.03 for protocol A and 0.14 mSv ± 0.04 for protocol B (P < .005). Diagnostic acceptability and depiction of bronchovascular structures at lung window settings were graded as almost excellent for both protocols, but protocol B was inferior to protocol A for mediastinal assessment (P < .02). Patients with CF had moderate lung disease with a mean Bhalla score of 9.2 ± 5.3 (range, 0-19), compared with that of patients without CF (1.1 ± 1.4; P < .001). There was excellent correlation between thin-section CT and chest radiography (r = 0.88-0.92; P < .001). CONCLUSION Low-dose thin-section CT can be performed at lower effective doses than can standard CT, approaching those of chest radiography. Low-dose thin-section CT could be appropriate for evaluating bronchiectasis in pediatric patients, yielding appropriate information about lung parenchyma and bronchovascular structures.

Imaging of Hematuria

Hematuria may have a number of causes, of which the more common are urinary tract calculi, urinary tract infection, urinary tract neoplasms (including renal cell carcinoma and urothelial tumors), trauma to the urinary tract, and renal parenchymal disease. This article discusses the current status of imaging of patients suspected of having urologic causes of hematuria. The role of all modalities, including plain radiography, intravenous urography or excretory urography, retrograde pyelography, ultrasonography, and multidetector computed tomography (MDCT) in evaluation of these patients is discussed. The article highlights the current status of MDCT urography in imaging of patients with hematuria, and discusses various-often controversial-issues, such as optimal protocol design, accuracy of the technique in imaging of the urothelium, and the significant issue of radiation dose associated with MDCT urography.

Diagnostic Accuracy of Computed Tomography Using Lower Doses of Radiation for Patients With Crohn's Disease

BACKGROUND & AIMS Magnetic resonance and ultrasonography have increasing roles in the initial diagnosis of Crohns disease, but computed tomography (CT) with positive oral contrast agents is most frequently used to identify those with acute extramural complications. However, CT involves exposure of patients to radiation. We prospectively compared the diagnostic accuracy of low-dose CT (at a dose comparable to that used to obtain an abdominal radiograph) with conventional-dose CT in patients with active Crohns disease. METHODS Low and conventional dose CT of the abdomen and pelvis were acquired from 50 patients with Crohns disease, referred from an inflammatory bowel disease service (20 male; median age, 34 years). Acute complications of Crohns disease were suspected. Iterative reconstruction was performed on all CT datasets to facilitate dose reduction. Three radiologists reviewed the low-dose CT images before the conventional-dose CT images. RESULTS The median effective dose (interquartile range) of radiation for the low-dose CT was reduced by 72% from that of conventional CT: from 3.5 mSv (3-5.08 mSv) to 0.98 mSv (0.77-1.42 mSv) (P < .001). As expected, the quality indexes of the low-dose images were inferior to those of the conventional-dose images, but no clinically significant diagnostic findings were missed with low-dose imaging. Follow-up CT examinations were recommended for 5 patients; 1 had a cervical tumor, 1 had a pancreatic lesion, and 3 had intra-abdominal abscess. In each case, the image obtained by low-dose CT was considered sufficient for diagnosis. CONCLUSIONS Although low-dose CT images are of lower quality than images obtained with conventional doses of radiation, no clinically significant diagnostic findings were missed from low-dose CT images of patients with Crohns disease. The low-dose CT was obtained at a median effective dose equivalent to 1.4 abdominal radiographs.

Radiologic imaging in cystic fibrosis: cumulative effective dose and changing trends over 2 decades.

OBJECTIVE With the increasing life expectancy for patients with cystic fibrosis (CF), and a known predisposition to certain cancers, cumulative radiation exposure from radiologic imaging is of increasing significance. This study explores the estimated cumulative effective radiation dose over a 17-year period from radiologic procedures and changing trends of imaging modalities over this period. METHODS Estimated cumulative effective dose (CED) from all thoracic and extrathoracic imaging modalities and interventional radiology procedures for both adult and pediatric patients with CF, exclusively attending a nationally designated CF center between 1992-2009 for > 1 year, was determined. The study period was divided into three equal tertiles, and estimated CED attributable to all radiologic procedures was estimated for each tertile. RESULTS Two hundred thirty patients met inclusion criteria (2,240 person-years of follow-up; 5,596 radiologic procedures). CED was > 75 mSv for one patient (0.43%), 36 patients (15.6%) had a CED between 20 and 75 mSv, 56 patients (24.3%) had a CED between 5 and 20 mSv, and in 138 patients (60%) the CED was estimated to be between 0 and 5 mSv over the study period. The mean annual CED per patient increased consecutively from 0.39 mSv/y to 0.47 mSv/y to 1.67 mSv/y over the tertiles one to three of the study period, respectively (P < .001). Thoracic imaging accounted for 46.9% of the total CED and abdominopelvic imaging accounted for 42.9% of the CED, respectively. There was an associated 5.9-fold increase in the use of all CT scanning per patient (P < .001). CONCLUSIONS This study highlights the increasing exposure to ionizing radiation to patients with CF as a result of diagnostic imaging, primarily attributable to CT scanning. Increased awareness of CED and strategies to reduce this exposure are needed.

Imaging of Cholecystitis

tients, such as those in the ICU, in whom clin -ical signs may be masked and imaging signs are less specific compared with the ambulant population [6]. Forty percent of patients with acute cholecystitis develop complications [7] (Table 1), including emphysematous chole-cystitis, which is seen more commonly in men and diabetic patients, with calculi present in less than 50% of cases [8]. Recurrent acute cholecystitis or biliary colic usually associat-ed with gallstones leads to low-grade inflam-mation and fibrosis of the gallbladder wall, which characterizes chronic cholecystitis [8].

Radiologic Percutaneous Gastrostomy: Review of Potential Complications and Approach to Managing the Unexpected Outcome

OBJECTIVE Radiologic percutaneous gastrostomy tube placement is a widely accepted method of enteral access for patients requiring long-term nutritional support for a variety of conditions. Although the safety of this procedure is well documented, complications do occur. The purpose of this article is to review the major and minor complications associated with gastrostomy tube placement and to present appropriate and effective management strategies. CONCLUSION Familiarity with the potential complications, techniques for their prevention, and strategies for treatment will help practicing interventional radiologists successfully manage all possible outcomes.

Modest benefit of total parenteral nutrition and chemotherapy after venting gastrostomy tube placement

OBJECTIVE The aim of the study is to review a single institutions experience with gastrostomy tubes (GTs) performed for malignant bowel obstruction from gynecologic cancers. METHODS Women with gynecologic cancers who underwent venting GT placement from 2000 to 2008 were identified and clinical data were extracted. Logistic regression and spearman correlational coefficients were used to determine relationships between variables. Survival analysis was performed using the Kaplan-Meier method and a Cox proportional hazard model. RESULTS We identified 115 women who underwent GT placement, the majority of whom were diagnosed with ovarian cancer (84%). Median time from cancer diagnosis to GT placement was 2.2 years. Median survival following GT placement was 5.6 weeks. A majority (56%) developed GT complications requiring GT revision. While burden of disease as assessed on CT scan by the validated peritoneal cancer index (PCI) was not associated with survival, low CA-125 within one week of GT placement was associated with improved survival (p<0.01). TPN was administered in 36% of women, was associated with concurrent chemotherapy (p<0.001) and a 5 week survival benefit (p<0.01). Chemotherapy after GT was administered in 40% of women and was associated with a 10 week survival benefit (p<0.001). Age-adjusted multivariate analysis identified chemotherapy as the only independent variable associated with survival. CONCLUSIONS Women with malignant bowel obstructions from gynecologic cancers requiring palliative GT placement had a guarded prognosis measured in weeks. Gastrostomy tubes near the end of life had a high rate of complications requiring medical intervention. Chemotherapy after GT was associated with TPN administration, and both were associated with a modest extension in survival.

Imaging of Biliary Tract Disease

W551 disease believed to increase the risk of cholangiocarcinoma [3]. Sclerosing cholangitis often presents with clinical features of biliary obstruction, such as jaundice and pruritus, but usually in the absence of signs of infection. Primary sclerosing cholangitis tends to involve the intrahepatic bile ducts to a greater extent than the extrahepatic ducts. Approximately 15% of patients with primary sclerosing cholangitis develop cholangiocarcinoma [4]. Cholangiocarcinoma is less common than other hepatic and cholecystic malignancies, representing approximately 1% of all malignancies. Most cholangiocarcinomas are adenocarcinomas [5]. Most patients with cholangiocarcinoma present between the sixth and seventh decades of life; however, patients with primary sclerosing cholangitis can develop cholangiocarcinoma at a younger age [5]. The extrahepatic biliary ducts are affected more commonly than the intrahepatic ducts [5]. An increased serum CA19-9 level can also be observed in patients with cholangiocarcinoma, whereas elevated α-fetoprotein levels are associated with hepatocellular carcinoma rather than cholangiocarcinoma [5]. Biliary obstruction is most commonly due to choledocholithiasis. Obstruction may also be a consequence of biliary strictures, malignancy, iatrogenic disease, and parasitic disease [6]. Biliary obstruction precipitates acute suppurative cholangitis by causing hepatovenous reflux and subsequent bacteremia [7]. The organisms most commonly associated with acute suppurative cholangitis include Escherichia coli, Klebsiella species, Proteus species, Bacteroides species, and Pseudomonas aeruginosa [8]. The classic clinical presentation is of right upper quadrant pain, fever, and jaundice (Charcot triad), sometimes with hypotension and altered consciousness (Reynolds pentad) [6, 9]. Acute suppurative cholangitis may lead Imaging of Biliary Tract Disease

Imaging the small bowel.

Purpose of review Radiologic investigations continue to play a pivotal role in the diagnosis of pathologic conditions of the small intestine despite enhancement of capsule endoscopy and double-balloon endoscopy. Imaging techniques continue to evolve and new techniques in MRI in particular, are being developed. Recent findings Continued advances in computed tomography (CT) and MRI techniques have reinforced the importance of these imaging modalities in small bowel assessment. The more invasive enteroclysis technique yields better small bowel distension for both CT and MRI when compared with peroral enterography, but no clinically significant difference is seen in terms of diagnostic accuracy. Recent concern regarding radiation exposure means that MRI is gaining in popularity. Fluoroscopic studies such as barium follow through and small bowel enteroclysis are being replaced by the cross-sectional alternatives. Contrast-enhanced ultrasound is showing results comparable with CT and MRI, but concern remains regarding reproducibility, especially outside centres that specialize in advanced sonographic techniques. Summary CT and MRI enterography are comparable first-line modalities for patients with suspected small bowel disease, but magnetic resonance enterography is favoured given the absence of ionizing radiation. Capsule endoscopy is a reasonable alternative investigation in exploration of chronic gastrointestinal blood loss, but is best kept as a second-line test in patients with other symptoms.

Image-Guided Percutaneous Splenic Biopsy and Drainage

Percutaneous splenic biopsy and drainage are relatively safe and accurate procedures. The risk of major complication (1.3%) following percutaneous splenic biopsy does not exceed that of other solid intra-abdominal organ biopsies, and it has less morbidity and mortality than splenectomy. Both computed tomography and ultrasound can be used to provide image guidance for biopsy and drainage. The safety profile of fine-needle aspiration cytology is better than core needle biopsy, but core biopsy has superior diagnostic accuracy.