C-reactive protein and radiographic findings of lower respiratory tract infection in infants.

AIM: To evaluate the association between C-reactive protein (CRP) and radiological evidence of lower respiratory tract infection (LRTI) in infants. METHODS: All patients aged less than 4 years who presented with suspected lower respiratory tract infection, who received a peri-presentation chest radiograph and CRP blood measurement over an 18-mo period were included in the study. Age, gender, source of referral, CRP, white cell count, neutrophil count along with the patients' symptoms and radiologist's report were recorded. RESULTS: Three hundred and eleven patients met the inclusion criteria. Abnormal chest radiographs were more common in patients with elevated CRP levels (P < 0.01). Radiologic signs of LRTI were identified in 73.7% of chest radiographs when a patient had a CRP level between 50-99 mg/L. CRP levels were a better predictor of positive chest radiograph findings for those aged greater than I year compared to those 1 year or less. CONCLUSION: CRP may be used in patients with suspected LRTI diagnosis to select those who are likely to have positive findings on chest radiograph, thus reducing unnecessary chest radiographs.

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

INTRODUCTION: 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. METHODS: One hundred and fifty consecutive patients who presented to the Emergency Department of a tertiary referral neurosciences centre within a time window suitable for intravenous thrombolytic therapy were included. Images were wirelessly transmitted to a tablet computer (iPad 3rd Generation, model = A1430, Apple, Cupertino, CA) and were reviewed by radiologists with three levels of experience for signs of intracranial haemorrhage, large vessel occlusion and parenchymal infarction. Reference standard interpretation was performed by two neuroradiologists using a diagnostic monochrome display. RESULTS: Consensus neuroradiologist review on the tablet display found and correctly classified all of the 23 cases of intracranial haemorrhage including 21 cases of parenchymal haematoma, two cases of petechial haemorrhage and one patient with an acute subdural haematoma. Less experienced readers missed cases of petechial and subdural haematomas. There was excellent agreement between the tablet and diagnostic monochrome display in cases with no infarct or extensive parenchymal infarction. CONCLUSIONS: Tablet computers can be used to facilitate rapid preliminary CT interpretation in patients with acute stroke in the remote setting.

Effects of oral contrast on dose in abdominopelvic computed tomography with pure iterative reconstruction.

AIM: To assess the effect of neutral (NC) and positive (PC) oral contrast use on patient dose in low-dose abdominal computed tomography (CT). METHODS: Low-dose clinically indicated CTs were performed on 79 Crohn's patients (35 = PC, 1 L 2% gastrografin; 44 = NC, 1.5 L polyethylene glycol). Scanner settings for both acquisitions were identical apart from 25 s difference in intravenous contrast timing. Body mass index (BMI), scan-ranges, dose-length product and size-specific dose estimated were recorded. Data was reconstructed with pure model-based iterative reconstruction. Image quality was objectively and subjectively analysed. Data analysis was performed with Statistical Package for Social Scientists. RESULTS: Higher doses were seen in neutral contrast CTs (107.60 ± 78.7 mGy.cm, 2.47 ± 1.21 mGy vs 85.65 ± 58.2 mGy.cm, 2.18 ± 0.96 mGy). The difference was significant in 2 of 4 BMI groups and in those that had both NC and PC investigations. Image-quality assessment yielded 6952 datapoints. NC image quality was significantly superior (P < 0.001) (objective noise, objective signal to noise ratio, subjective spatial resolution, subjective contrast resolution, diagnostic acceptability) at all levels. NC bowel distension was significantly (P < 0.001) superior. CONCLUSION: The use of polyethylene glycol as a neutral OC agent leads to higher radiation doses than standard positive contrast studies, in low dose abdominal CT imaging. This is possibly related to the osmotic effect of the agent resulting in larger intraluminal fluid volumes and resultant increased overall beam attenuation.

Low-Dose Carotid Computed Tomography Angiography Using Pure Iterative Reconstruction.

UNLABELLED: The aim of this study was to assess if a low-dose carotid computed tomography angiography (CTA) performed with pure iterative reconstruction (IR) is comparable to a conventional dose CTA protocol. METHODS: Twenty patients were included. Radiation dose was divided into a low-dose acquisition reconstructed with pure IR and a conventional dose acquisition reconstructed with 40% hybrid IR. Dose, image noise, contrast resolution, spatial resolution, and carotid artery stenosis were measured. RESULTS: Mean effective dose was significantly lower for low-dose than conventional dose studies (1.84 versus 3.71 mSv; P < 0.001). Subjective image noise, contrast resolution, and spatial resolution were significantly higher for the low-dose studies. There was excellent agreement for stenosis grading accuracy between low- and conventional dose studies (Cohen κ = 0.806). CONCLUSIONS: A low-dose carotid CTA protocol reconstructed with pure IR is comparable to a conventional dose CTA protocol in terms of image quality and diagnostic accuracy while enabling a dose reduction of 49.6%.

Feasibility of low-dose CT with model-based iterative image reconstruction in follow-up of patients with testicular cancer.

PURPOSE: We examine the performance of pure model-based iterative reconstruction with reduced-dose CT in follow-up of patients with early-stage testicular cancer. METHODS: Sixteen patients (mean age 35.6 ± 7.4 years) with stage I or II testicular cancer underwent conventional dose (CD) and low-dose (LD) CT acquisition during CT surveillance. LD data was reconstructed with model-based iterative reconstruction (LD-MBIR). Datasets were objectively and subjectively analysed at 8 anatomical levels. Two blinded clinical reads were compared to gold-standard assessment for diagnostic accuracy. RESULTS: Mean radiation dose reduction of 67.1% was recorded. Mean dose measurements for LD-MBIR were: thorax - 66 ± 11 mGy cm (DLP), 1.0 ± 0.2 mSv (ED), 2.0 ± 0.4 mGy (SSDE); abdominopelvic - 128 ± 38 mGy cm (DLP), 1.9 ± 0.6 mSv (ED), 3.0 ± 0.6 mGy (SSDE). Objective noise and signal-to-noise ratio values were comparable between the CD and LD-MBIR images. LD-MBIR images were superior (p < 0.001) with regard to subjective noise, streak artefact, 2-plane contrast resolution, 2-plane spatial resolution and diagnostic acceptability. All patients were correctly categorised as positive, indeterminate or negative for metastatic disease by 2 readers on LD-MBIR and CD datasets. CONCLUSIONS: MBIR facilitated a 67% reduction in radiation dose whilst producing images that were comparable or superior to conventional dose studies without loss of diagnostic utility.

Model-Based Iterative Reconstruction in CT Enterography.

OBJECTIVE: The purpose of this study was to analyze the performance of pure model-based iterative reconstruction (MBIR) in low-dose CT enterography. SUBJECTS AND METHODS: Forty-four patients with Crohn disease referred for CT enterography were included. Low-dose modified-protocol and conventional-protocol CT datasets were contemporaneously acquired. Conventional-protocol image formation was performed with 40% adaptive statistical iterative reconstruction (ASIR). Modified-protocol data were reconstructed with 100% MBIR and 40% ASIR. Image quality was assessed subjectively and objectively at six levels. Independent clinical interpretations by two fully blinded radiologists were compared with reference standard consensus reviews by two nonblinded readers who had access to clinical information, previous imaging studies, and medical records. RESULTS: A 74.7% average radiation dose reduction was seen: low-dose modified-protocol effective dose, 1.61 ± 1.18 mSv (size-specific-dose-estimate, 2.47 ± 1.21 mGy); conventional-protocol effective dose, 6.05 ± 2.84 mSv (size-specific-dose-estimate, 9.25 ± 2.9 mGy). Image quality assessment yielded 9372 data points. Objective noise on modified-protocol MBIR images was superior (p < 0.05) to that with the conventional protocol at three of six levels and comparable at the other three levels. Modified-protocol images were superior to conventional-protocol ASIR images (p < 0.05 in all cases) for subjective noise, spatial resolution, contrast resolution, streak artifact, and diagnostic acceptability on coronal reconstructions. Axial diagnostic acceptability was superior for conventional-protocol ASIR (p = 0.76). For both readers, modified-protocol MBIR clinical readings agreed more closely with reference standard readings than did conventional-protocol ASIR readings with regard to bowel wall disease assessment (κ = 0.589 and 0.700 vs 0.583 and 0.564). Overall Crohn disease activity grade (κ = 0.549 and 0.441 vs 0.315 and 0.596) and detection of acute complications (κ = 1.0 and 0.689 vs 0.896 and 0.896) were comparable when evaluated on conventional-protocol ASIR and modified-protocol MBIR images. CONCLUSION: Low-dose CT enterography with MBIR yields images that are comparable to or superior to conventional images.

Medical student perceptions of radiology use in anatomy teaching.

The use of radiology in the teaching of anatomy to medical students is gaining in popularity; however, there is wide variation in how and when radiology is introduced into the curriculum. The authors sought to investigate students' perceptions regarding methods used to depict and teach anatomy and effects of integrated radiology instruction on students' abilities to correctly identify imaging modalities and anatomical structures on radiological images. First-year medical students completed questionnaires at the beginning and end of the first academic year that incorporated ten hours of radiologic anatomy teaching in the anatomy curriculum. Questions used a combination of Likert scales, rankings, and binary options. Students were tested on their ability to identify radiology modalities and anatomical structures on radiology images. Preresponse and postresponse rates were 93% (157/168) and 85% (136/160), respectively. Postmodule, 96.3% of students wanted the same or more radiology integration. Furthermore, 92.4% premodule and 96.2% postmodule agreed that "Radiology is important in medical undergraduate teaching." Modality and structure identification scores significantly increased from 59.8% to 64.3% (P < 0.001) and from 47.4% to 71.2% (P < 0.001), respectively. The top three preferred teaching formats premodule and postmodule were (1) anatomy laboratory instruction, (2) interactive sessions combining radiology with anatomy, and (3) anatomy lectures. Postmodule, 38.3% of students were comfortable reviewing radiology images. Students were positive about integrating radiology into anatomy teaching and most students wanted at least the same level of assimilation but that it is used as an adjunct rather than primary method of teaching anatomy.

Medical student knowledge regarding radiology before and after a radiological anatomy module: implications for vertical integration and self-directed learning.

OBJECTIVES: To examine the impact that anatomy-focused radiology teaching has on non-examined knowledge regarding radiation safety and radiology as a specialty. METHODS: First-year undergraduate medical students completed surveys prior to and after undertaking the first-year anatomy programme that incorporates radiological anatomy. Students were asked opinions on preferred learning methodology and tested on understanding of radiology as a specialty and radiation safety. RESULTS: Pre-module and post-module response rates were 93 % (157/168) and 85 % (136/160), respectively. Pre-module and post-module, self-directed learning (SDL) ranked eighth (of 11) for preferred gross-anatomy teaching formats. Correct responses regarding radiologist/radiographer roles varied from 28-94 % on 16 questions with 4/16 significantly improving post-module. Identification of modalities that utilise radiation significantly improved for five of eight modalities post-module but knowledge regarding relative amount of modality-specific radiation use was variable pre-module and post-module. CONCLUSIONS: SDL is not favoured as an anatomy teaching method. Exposure of students to a radiological anatomy module delivered by senior clinical radiologists improved basic knowledge regarding ionising radiation use, but there was no improvement in knowledge regarding radiation exposure relative per modality. A possible explanation is that students recall knowledge imparted in didactic lectures but do little reading around the subject when the content is not examined. TEACHING POINTS: • Self-directed learning is not favoured as a gross anatomy teaching format amongst medical students. • An imaging anatomy-focused module improved basic knowledge regarding ionising radiation use. • Detailed knowledge of modality-specific radiation exposure remained suboptimal post-module. • Knowledge of roles within a clinical radiology department showed little change post-module.

A prospective feasibility study of sub-millisievert abdominopelvic CT using iterative reconstruction in Crohn's disease.

OBJECTIVE: Iterative reconstruction (IR) allows diagnostic CT imaging with less radiation exposure than filtered back projection (FBP). We studied an IR low-dose CT abdomen/pelvis (LDCTAP) protocol, designed to image at an effective dose (ED) approximating 1 mSv in patients with Crohn's disease (CD). METHODS: Forty patients, mean age 37 ± 13.4 years (range 17-69), with CD underwent two synchronous CT protocols (conventional-dose (CDCTAP) and LDCTAP). CDCTAP and LDCTAP images were compared for diagnostic acceptability, yield, image quality and ED (in millisieverts). The optimal level of IR for LDCTAP was also studied. RESULTS: LDCTAP yielded a mean ED of 1.3 ± 0.8 mSv compared with 4.7 ± 2.9 mSv for CDCTAP, reducing ED by 73.7 ± 3.3 % (mean dose reduction, 3.5 ± 2.1 mSv; P < 0.001) and dose length product by 73.6 ± 2.6 % (P < 0.001). Sub-millisievert (0.84 mSv) imaging was performed for patients with a body mass index (BMI) less than 25 (i.e. 63 % of our cohort). LDCTAP resulted in increased image noise and reduced diagnostic acceptability compared with CDCTAP despite use of IR, but detection of extra-luminal complications was comparable. CONCLUSION: Patients with suspected active CD can be adequately imaged using LDCTAP, yielding comparable information regarding extent, activity and complications of CD compared with CDCTAP, but with 74 % less dose. LDCTAP at doses equivalent to that of two abdominal radiographs represents a feasible alternative to CDCTAP. KEY POINTS: • Radiation dose is a concern when imaging patients with Crohn's disease. • New techniques allow low-dose abdominopelvic CT with acceptable image quality. • Using hybrid iterative reconstruction, its diagnostic yield compares well with that of conventional CT. • Sub-millisievert CT of patients with Crohn's disease appears technically and clinically feasible.

Computed tomography colonography technique: the role of intracolonic gas volume.

Introduction. Poor distention decreases the sensitivity and specificity of CTC. The total volume of gas administered will vary according to many factors. We aim to determine the relationship between the volume of retained gas at the time of image acquisition and colonic distention and specifically the presence of collapsed bowel segments at CTC. Materials and Methods. All patients who underwent CTC over a 12-month period at a single institution were included in the study. Colonic luminal distention was objectively scored by 2 radiologists using an established 4-point scale. Quantitative analysis of the volume of retained gas at the time of image acquisition was conducted using the threshold 3D region growing function of OsiriX. Results. 108 patients were included for volumetric analysis. Mean retained gas volume was 3.3 L. 35% (38/108) of patients had at least one collapsed colonic segment. Significantly lower gas volumes were observed in the patients with collapsed colonic segments when compared with those with fully distended colons 2.6 L versus 3.5 L (P = 0.031). Retained volumes were significantly higher for the 78% of patients with ileocecal reflux at 3.4 L versus 2.6 L without ileocecal reflux (P = 0.014). Conclusion. Estimation of intraluminal gas volume at CTC is feasible using image segmentation and thresholding tools. An average of 3.5 L of retained gas was found in diagnostically adequate CTC studies with significantly lower mean gas volume observed in patients with collapsed colonic segments.

CT Densitometry as a Predictor of Pulmonary Function in Lung Cancer Patients.

PURPOSE: Preoperative pulmonary assessment is undertaken in patients with resectable lung cancer to identify those at increased risk of perioperative complications. Guidelines from the American College of Chest Physicians indicate that if the FEV(1) and DLCO are ≥60% of predicted, patients are suitable for resection without further evaluation. The aim of our study is to determine if quantitative measures of lung volume and density obtained from pre-operative CT scans correlate with pulmonary function tests. This may allow us to predict pulmonary function in patients with lung cancer and identify patients who would tolerate surgical resection. MATERIALS AND METHODS: Patients were identified retrospectively from the lung cancer database of a tertiary hospital. Image segmentation software was utilized to estimate total lung volume, normal lung volume (values -500 HU to -910 HU), emphysematous volume (values less than -910 HU), and mean lung density from pre-operative CT studies for each patient and these values were compared to contemporaneous pulmonary function tests. RESULTS: A total of 77 patients were enrolled. FEV1 was found to correlate significantly with the mean lung density (r=.762, p<.001) and the volume of emphysema (r= -.678, p<.001). DLCO correlated significantly with the mean lung density (r =.648, p<.001) and the volume of emphysematous lung (r= -.535, p<.001). CONCLUSION: The results of this study suggest that both FEV1 and DLCO correlate significantly with volume of emphysema and mean lung density. We now plan to prospectively compare these CT parameters with measures of good and poor outcome postoperatively to identify CT measures that may predict surgical outcome preoperatively.

Evaluation of the efficacy and safety of percutaneous biopsy of lung.

INTRODUCTION: Percutanous needle biopsy of the lung (PNBL), under image guidance, has established itself as a safe and effective minimally-invasive method of obtaining a tissue diagnosis of pulmonary lesions, for selected patients with suspected pathologic processes. The purpose of this study was to evaluate the diagnostic yield and safety of percutaneous core biopsy of the lung (PCBL) without Fine Needle Aspiration Biopsy (FNAB), with specific attention to potential risk factors that may predict post-biopsy pneumothorax. MATERIALS AND METHODS: A retrospective analysis of 75 consecutive PCBL procedures between January 2006 to March 2008 involving 72 patients with a documented pulmonary nodule or mass lesion on CT scan of Thorax. The study population included 38 males (52.8%) and 34 females (47.2%) aged 20-85 years (mean age 63.6 years). A co-axial cutting system with a 19-gauge outer needle and a 20-gauge inner automated cutting needle (Temno, Allegiance Healthcare Corporation, Ohio, USA) was used in all patients. RESULTS: Lesions varied in size from 0.7cm to 10.7cm (mean maximum trans-axial diameter 3.1cm). The mean number of core biopsy samples obtained was 3.1 (range 1-5). Of the 75 PCBL procedures, 71 yielded specimens adequate for histopathologic evaluation, consistent with a technical success rate of 95%. Malignancy was detected in 48 specimens (64%) and benign diagnoses were identified in 23 specimens (31%). As mentioned, 4 specimens (5%) were nondiagnostic. The most common biopsy-induced complication was pneumothorax, occurring in 15 patients (20%), with 4 (5.3%) requiring thoracostomy tube placement. CONCLUSION: PCBL without FNAB, under CT fluoroscopy guidance, has an excellent diagnostic accuracy in obtaining a conclusive histologic diagnosis of thoracic lesions and is comparable to FNAB in terms of safety and rates of occurence of complications.

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.