Siobhan B. O'Neill

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.

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

Selection of Symptomatic Patients With Crohn's Disease for Abdominopelvic Computed Tomography: Role of Serum C-Reactive Protein

Background Results of previous studies have shown that repeated abdominopelvic computed tomography (CT) examinations can lead to substantial cumulative diagnostic radiation exposure in patients with Crohns disease (CD). Improved selection of patients referred for CT will reduce unnecessary radiation exposure. This study examines if serum C-reactive protein (CRP) concentration predicts which symptomatic patients with CD are likely to have significant disease activity or disease complications (such as abscess) detected on abdominopelvic CT. Methods All abdominopelvic CTs performed on patients with CD at a tertiary referral centre during the period June 2003 to June 2008 were identified. CT findings were coded by a pair of independent blinded senior radiologists for (i) small bowel luminal disease, (ii) large bowel luminal disease, (iii) mesenteric inflammatory changes, (iv) penetrating disease (fistulas, abscess, or phlegmon), (v) acute disease complications (obstruction or perforation), and (vi) acute non-CD findings. Imaging findings were correlated with serum CRP checked within 14 days before imaging. The reference range for CRP was defined as 0–5 mg/L. Results A total of 147 patients with symptomatic CD had a CRP assay performed within 14 days before undergoing abdominopelvic CT. The median time from CRP assay to imaging was 2 days (interquartile range, 0-6 days). Median CRP before imaging was 24 mg/L (interquartile range, 6-88 mg/L). CT was normal in 34 of 147 case (23.1%). Patients with normal CRP (n = 36) were significantly less likely to have penetrating disease (odds ratio [OR], 0.04 [95% confidence interval {CI}, 0.01-0.7]; P < .001) or large bowel luminal disease (OR, 0.3 [95% CI, 0.1-0.8]; P < .05). Normal CRP excluded penetrating disease with a sensitivity of 1.0 (95% CI, 0.87-1.0). CRP levels did not correlate with the presence of small bowel luminal disease (n = 82), mesenteric inflammatory changes (n = 68), or acute disease complications (n = 10). Conclusion Symptomatic patients with CD and normal serum CRP are unlikely to have evidence of abscess, fistulating disease, or large bowel luminal disease detected on abdominopelvic CT. However, abdominopelvic CT may demonstrate evidence of clinically significant non-penetrating CD or complications, including perforation and acute obstruction, regardless of serum CRP concentration.

CT-based estimation of intracavitary gas volumes using threshold-based segmentation: In vitro study to determine the optimal threshold range

Introduction: This study investigated the optimal Hounsfield unit (HU) threshold range when using threshold‐based segmentation to estimate volumes of contained gas (i.e. intestinal gas) on CT.

Interventional Radiology and the Care of the Oncology Patient

Interventional Radiology (IR) is occupying an increasingly prominent role in the care of patients with cancer, with involvement from initial diagnosis, right through to minimally invasive treatment of the malignancy and its complications. Adequate diagnostic samples can be obtained under image guidance by percutaneous biopsy and needle aspiration in an accurate and minimally invasive manner. IR techniques may be used to place central venous access devices with well-established safety and efficacy. Therapeutic applications of IR in the oncology patient include local tumour treatments such as transarterial chemo-embolisation and radiofrequency ablation, as well as management of complications of malignancy such as pain, organ obstruction, and venous thrombosis.

Computed tomography dose optimisation in cystic fibrosis: A review.

Cystic fibrosis (CF) is the most common autosomal recessive disease of the Caucasian population worldwide, with respiratory disease remaining the most relevant source of morbidity and mortality. Computed tomography (CT) is frequently used for monitoring disease complications and progression. Over the last fifteen years there has been a six-fold increase in the use of CT, which has lead to a growing concern in relation to cumulative radiation exposure. The challenge to the medical profession is to identify dose reduction strategies that meet acceptable image quality, but fulfil the requirements of a diagnostic quality CT. Dose-optimisation, particularly in CT, is essential as it reduces the chances of patients receiving cumulative radiation doses in excess of 100 mSv, a dose deemed significant by the United Nations Scientific Committee on the Effects of Atomic Radiation. This review article explores the current trends in imaging in CF with particular emphasis on new developments in dose optimisation.

Chronic Pneumoperitoneum in Systemic Sclerosis

A 71-year-old female patient with a known diagnosis of scleroderma attended the emergency department with a subacute history of minor weight loss, abdominal distension, and prominent bowel sounds, without a change in bowel habit. Scleroderma in this patient had been complicated by chronic intestinal pseudo-obstruction and bacterial overgrowth. Regular medications included rifaximin 400 mg three times daily in 4-week pulses, interrupted by 2-week rest periods, when an oral probiotic was taken. Other medications included laxatives, promotility agents, calcium supplements, and a bisphosphonate. She had a history, 5 years previously, of partial small bowel volvulus, which required laparotomy with a fibrous band division. Examination revealed a soft, nontender tympanitic abdomen, with marked distension and an uncomplicated incisional hernia at the site of a previous laparotomy. She had a plain abdominal radiograph, after which she had a computed tomography (CT) of the abdomen and pelvis (Figure 1). The CT demonstrated a large volume of free intraperitoneal gas consistent with extensive pneumoperitoneum. There also was extensive retroperitoneal free air but no signs of visceral perforation, pneumatosis intestinalis, or pneumatosis coli. The large bowel was dilated but without evidence of a transition point to suggest mechanical obstruction. Hematologic and biochemical investigations were unremarkable. Because the patient was systemically well without signs of acute peritonitis, she was managed conservatively. At outpatient follow-up 3 months later, she had persisting abdominal distension, she remained clinically well. A repeat

CT of the head for acute stroke: Diagnostic performance of a tablet computer prior to intravenous thrombolysis

The authors propose that tablet computers could benefit patients with acute stroke in the remote care setting, where time to and accuracy of CT interpretation greatly influences patient outcome.

Accurate tissue characterization in low-dose CT imaging with pure iterative reconstruction

We assess the ability of low‐dose hybrid iterative reconstruction (IR) and ‘pure’ model‐based IR (MBIR) images to maintain accurate Hounsfield unit (HU)‐determined tissue characterization.