Under-reporting of osteoporotic vertebral fractures on computed tomography

Purpose

Osteoporotic vertebral fractures are frequently asymptomatic. They are often not diagnosed clinically or radiologically. Despite this, prevalent osteoporotic vertebral fractures predict future osteoporotic fractures and are associated with increased mortality and morbidity. Appropriate management of osteoporosis can reduce future fracture risk. Fractures on lateral chest radiographs taken for other conditions are frequently overlooked by radiologists. Our aim was to assess the value of computed tomography (CT) in the diagnosis of vertebral fracture and identify the frequency with which significant fractures are missed.

Materials and methods

The thoracic CT scans of 100 consecutive male and 100 consecutive female patients over 55 years were reviewed. CT images were acquired on General Electric Lightspeed multi-detector (MD) CT scanners (16 or 32 row) using 1.25 mm slice thickness. Midline sagittal images were reconstructed from the 3D volume images. The presence of moderate (25–40% height loss) or severe (>40% height loss) vertebral fractures between T1 and L1 was determined using an established semi-quantitative method and confirmed by morphological measurement. Results were compared with the formal CT report.

Results

Scans of 192 patients were analysed (95 female; 97 male); mean age 70.1 years. Thirty-eight (19.8%) patients had one or more moderate to severe vertebral fractures. Only 5 (13%) were correctly reported as having osteoporotic fractures in the official report. The sensitivity of axial CT images to vertebral fracture was 0.35.

Conclusion

Incidental osteoporotic vertebral fractures are under-reported on CT. The sensitivity of axial images in detecting these fractures is poor. Sagittal reformations are strongly recommended to improve the detection rate.     

Value of conventional chest radiography for the detection of coronary calcifications: comparison with MSCT

Purpose

To evaluate if computed tomography (CT) coronary calcium scoring is needed after detection of coronary calcifications on conventional chest radiographs.

Materials and methods

One hundred and five patients (67 men; 57.2 ± 12.8 years) with suspected coronary artery disease underwent conventional chest radiography and non-enhanced, retrospectively ECG-gated multislice spiral CT (MSCT) of the heart (4 mm × 2.5 mm, 120 kV, 133 mAs_eff.). Chest radiographs were assessed independently by two radiologists. Detection of coronary calcifications was compared between both methods. Sensitivity, specificity, negative and positive predictive values, median, 25% and 75% percentiles for the detection of coronary calcifications were calculated. Receiver operating characteristics (ROC) analyses were computed.

Results

In 90 patients, MSCT revealed coronary calcifications. The mean coronary calcium score was 526.2 (0–4784.5). On chest radiographs, coronary calcifications were correctly detected in 46 (61) patients by observer 1 (observer 2). The corresponding sensitivity was 51.1% in observer 1 and 67.8% in observer 2. Median of detected coronary calcifications was 361.9 (426.4) for observer 1 (observer 2). Corresponding 25% und 75% percentiles were 109.6 (109.6) and 798.5 (898.5). The area under the ROC curve was 0.636 for observer 1 and 0.715 for observer 2. There was no correlation between image quality and the detection of coronary calcifications on plain film radiographs.

Conclusion

As coronary calcifications of various extents are inconsistently detected on plain chest radiographs, CT calcium scoring may not be omitted even if coronary artery calcifications were detected on conventional chest radiographs.     

Repeat needle insertion in vertebroplasty to prevent re-collapse of the treated vertebrae

Purpose

Patients with un-relieved pain after vertebroplasty due to re-collapse of the cemented vertebrae have been reported. Here we report a technique of vertebroplasty that can reduce the incidence of re-collapse at the cemented vertebrae.

Materials and methods

Between March 2002 and September 2008, 134 patients with 205 painful vertebral compression fractures underwent vertebroplasty in our institutes. The indication of using this technique was unfilled area more than 25% of the vertebral body height in lateral radiograph. The vertebroplasty procedure was performed according to the technique described by Jensen. If the unfilled area were more than 25% of the vertebral body height in lateral radiograph, another needle would be inserted aiming at the unfilled area. As outcome measurement, a visual analog scale with 10 divisions and plain radiographs (to measure the anterior vertebral body height of cemented vertebrae) were used.

Results

Thirteen vertebrae were treated with this technique. The mean age was 74.4 years. The immediate post-vertebroplasty anterior vertebral height was 24.92 ± 3.59 mm, changed to 23.52 ± 3.54 mm at final follow-up. The visual analog scale decreased from a mean of 8.7 before vertebroplasty to 2.3 at final follow-up. The follow-up duration ranged from 15 to 38 months (mean 18.5 months). There was no case of re-collapse of the cemented vertebrae, and no procedure-related complications.

Conclusion

In the treatment of vertebral compression fractures by percutaneous vertebroplasty, repeat needle insertion to the unfilled area may be helpful to decrease the incidence of re-collapse of cemented vertebrae if the unfilled area is more than 25% of the vertebral body height in lateral radiograph.     

T2WI MRI and MRI-MDCT correlations of the osteoporotic vertebral compressive fractures

Purpose

The purpose of this study was to present the various vertebral bone signal and configuration patterns on T2WI MRI in osteoporotic benign fractures. The appearances were also assessed with thin slice MPR CT images.

Materials and methods

66 patients (43 women, 23 men; age range, 34–97 years; mean age, 76 years) with 100 vertebral compression fractures due to osteoporosis were included in our study. All cases are acute or subacute phase fractures which occurred within 1 month. Multiple fractures were observed in 29 patients, in 8 cases multiple concurrent fractures were proved by past radiograph or MRI. Three planes of T2WI (sagittal, coronal, axial) section images were correlated with the corresponding MDCT images.

Results

In our retrospective study, various signals and forms of vertebral body fractures were observed. The fracture zone (line) was classified 3 signal intensity patterns. (high; n = 24, low to intermediate; n = 16, low intensity; n = 38) on T2WI. The signal of the peri(para) fractured area were high (n = 6), intermediate to low (n = 41), low (n = 53)intensity. With CT correlative study, high, low to intermediate area were considered to be corresponded to the bone marrow edema, fibrous reparative tissue with/without the bony callus formation. The localization were as follows: sub-end plate band like lesion in 53, central in 16, anterior in 13, sub-endplate + anterior in 10, and complete (diffuse) in 8. In 10 cases, adjacent Schmorl's nodules were observed.

Conclusion

The various vertebral body signal patterns were observed in osteoporotic compressive fracture on T2WI. By MRI-CT correlations, high signal and low signal area on T2WI corresponded to the bone marrow edema, and the fibrous tissue or callus formation respectively.     

Assessment of osteoporotic vertebral fractures using specialized workflow software for 6-point morphometry

Purpose

To evaluate the time required, the accuracy and the precision of a model-based image analysis software tool for the diagnosis of osteoporotic fractures using a 6-point morphometry protocol.

Materials and methods

Lateral dorsal and lumbar radiographs were performed on 92 elderly women (mean age 69.2 ± 5.7 years). Institutional review board approval and patient informed consent were obtained for all subjects. The semi-automated and the manual correct annotations of 6-point placement were compared to calculate the time consumed and the accuracy of the software. Twenty test images were randomly selected and the data obtained by multiple perturbed initialisation points on the same image were compared to assess the precision of the system.

Results

The time requirement data of the semi-automated system (420 ± 67 s) were statistically different (p < 0.05) from that of manual placement (900 ± 77 s). In the accuracy test, the mean reproducibility error for semi-automatic 6-point placement was 2.50 ± 0.72% [95% CI] for the anterior–posterior reference and 2.16 ± 0.5% [95% CI] for the superior–inferior reference. In the precision test the mean error resulted averaged over all vertebrae was 2.6 ± 1.3% in terms of vertebral width.

Conclusions

The technique is time effective, accurate and precise and can, therefore, be recommended in large epidemiological studies and pharmaceutical trials for reporting of osteoporotic vertebral fractures.     

Comparison of diagnostic accuracy of Magnetic Resonance Imaging and Multidetector Computed Tomography in the detection of pelvic fractures

Objective

To compare diagnostic accuracy and interobserver reliability of Magnetic Resonance Imaging (MRI) and Multidetector Computed Tomography (MDCT) in the detection of acute pelvic fractures.

Materials and methods

In 38 consecutive patients (mean age 74.7 years) with a positive finding of anterior pelvis fracture in the conventional X-rays, pelvic MRI and MDCT were performed for further evaluation of pelvic ring fractures. Two radiologists independently read all data sets. Sensitivity and specificity were calculated based on mean scores for each method. Sensitivities of CT and MRI were compared using a paired proportion test (McNemar). Diagnostic validity of both methods was assessed by the interobserver variability using kappa statistics. Combined clinical data and findings from all imaging studies served as the reference standard.

Results

122 fractures were identified in the reference standard (37 sacral, 58 pubic, 22 acetabular, 1 ischial, 4 ilial). On average, MRI detected 96.3% whereas CT detected 77% of all fractures. With regard to sensitivity, MRI proved to be significantly better compared to MDCT (observer 1, p = 0.0009; observer 2, p = 0.0003 by observer 2). In particular, MRI performed better in the depiction of sacral fractures, reaching a sensitivity of 98.6% compared to 66.1% at CT. The interobserver variability was determined to be very good (k = 0.955 for MRI and 0.902 for MDCT).

Conclusion

MRI reaches a significantly higher sensitivity than CT in the detection of acute pelvic fractures, particularly of the sacrum. Especially in elderly patients with suspicion of a sacral fracture and negative results at MDCT, MRI may be considered as the next step in diagnostic workup.     

Sternal fracture in the emergency department: diagnostic value of multidetector CT with sagittal and coronal reconstruction images

Background

Multidetector CT (MDCT) is being increasingly used for patients with traumatic injuries in the emergency room. This is the first study to evaluate the diagnostic performance of MDCT for sternal fracture.

Patients and methods

For 87 patients who had motor vehicle accidents, we evaluated the diagnostic performance of MDCT for the sternal fractures. For 31 patients who underwent both MDCT and lateral radiography for the sternum, we compared the diagnostic performance of two examinations for the evaluation of sternal fracture.

Results

Thirty-two patients had sternal fractures and all the sternal fractures (sensitivity = 100%) were detected on MDCT, especially on the sagittal reconstruction images. However, the axial and coronal images detected 65% and 59% of all sternal fractures, respectively. For 31 patients who underwent both MDCT and lateral radiography for the sternum, MDCT showed superior diagnostic performance compared to that of radiography (accuracy = 97% and 77%, respectively, P = .02). For the one case that showed false positivity for sternal fracture on MDCT due to respiratory artifact, the lateral radiography enabled making the correct diagnosis.

Conclusion

Sternal fracture is frequently seen in patients who have blunt trauma injury secondary to motor vehicle accidents. MDCT, particularly sagittal images detect all of the sternal fractures, is superior to lateral radiography for diagnosis of sternal fracture. In the limited case that CT has severe motion artifact, additional radiography could help the diagnosis of sternal fracture.     

Prevalence of thoracolumbar vertebral fractures on multidetector CT: underreporting by radiologists

Objective

To evaluate the prevalence of osteoporotic vertebral fractures in patients undergoing multidetector computed tomography (MDCT) of the chest and/or abdomen.

Materials and methods

323 consecutive patients (196 males, 127 females) with a mean age of 62.6 years (range 20–88) who had undergone chest and/or abdominal MDCT were evaluated. Sagittal reformats of the spine obtained from thin section datasets were reviewed by two radiologists and assessed for vertebral fractures. Morphometric analysis using electronic calipers was performed on vertebral bodies which appeared abnormal upon visual inspection. A vertebral body height loss of 15% or more was considered a fracture and graded as mild (15–24%), moderate (25–49%) or severe (more than 50%). Official radiology reports were reviewed and whether the vertebral fractures had been reported or not was noted.

Results

31 out of 323 patients (9.5%) had at least 1 vertebral fracture and 7 of those patients had multiple fractures for a total of 41 fractures. Morphometric grading revealed 10 mild, 16 moderate and 15 severe fractures. Prevalence was higher in women (14.1%) than men (6.6%) and increased with patients age with a 17.1% prevalence in post-menopausal women. Only 6 out 41 vertebral fractures (14.6%) had been noted in the radiology final report while the remaining 35 (85.45) had not.

Conclusion

although vertebral fractures represent frequent incidental findings on multidetector CT studies and may be easily identified on sagittal reformats, they are often underreported by radiologists, most likely because of unawareness of their clinical importance.     

Computed tomography scout views vs. conventional radiography in body-packers – Delineation of body-packs and radiation dose in a porcine model

Objective

To compare abdominal computed tomography (CT) scout views with conventional radiography regarding radiation dose and delineation of drug packages in a porcine body-packer model.

Materials and methods

Nine samples of illicit drugs packed in ovoid plastic containers were consecutively placed in the rectum of a 121.5 kg pig cadaver. Antero-posterior and lateral scout views were obtained at 120 kVp and 80 mA, 150 mA and 200 mA, respectively, using a 64-row MDCT. Scout views were compared with conventional abdominal antero-posterior radiographs (77 kV and 106 ± 13 mAs). Visibility of three body pack characteristics (wrapping, content, shape) was rated independently by two radiologists and summarized to a delineation score ranging from 0 to 9 with a score ≥6 representing sufficient delineation. Mean delineation scores were calculated for each conventional radiography and single plane scout view separately and for a combined rating of antero-posterior and lateral scout views.

Results

Even the lowest single plane scout view delineation score (5.3 ± 2.0 for 80 mA lateral; 0.4 mSv; sensitivity = 44%) was significantly higher than for conventional radiographs (3.1 ± 2.5, p < 0.001; 2.4 ± 0.3 mSv; sensitivity = 11%). Combined reading of antero-posterior and lateral scout views 80 mA yielded sufficient delineation (6.2 ± 1.4; 0.8 mSv; sensitivity = 56%).

Conclusions

All CT scout views showed significantly better delineation ratings and sensitivity than conventional radiographs. Scout views in two planes at 80 mA provided a sufficient level of delineation and a sensitivity five times higher than conventional radiography at less than one third of the radiation dose. In case of diagnostic insecurity, CT can be performed without additional logistical effort.     

Intermodality comparison between 3D perfusion CT and 18F-FDG PET/CT imaging for predicting early tumor response in patients with liver metastasis after chemotherapy: Preliminary results of a prospective study

Objectives

To evaluate the feasibility of 3D perfusion CT for predicting early treatment response in patients with liver metastasis from colorectal cancer.

Methods

Seventeen patients with colon cancer and liver metastasis were prospectively enroled to undergo perfusion CT and 18F-FDG-PET/CT before and after one-cycle of chemotherapy. Two radiologists and three nuclear medicine physicians measured various perfusion CT and PET/CT parameters, respectively from the largest hepatic metastasis. Baseline values and reduction rates of the parameters were compared between responders and nonresponders. Spearman correlation test was used to correlate perfusion CT and PET/CT parameters, using RECIST criteria as reference standard.

Results

Nine patients responded to treatment, eight patients were nonresponders. Baseline SUV_mean30 on PET/CT, reduction rates of 30% metabolic volume and 30% lesion glycolysis (LG₃₀) on PET/CT and blood flow (BF) and flow extraction product (FEP) on perfusion CT after chemotherapy were significantly different between responders and nonresponders (P = 0.008–0.046). Reduction rates of BF (correlation coefficient = 0.630) and FEP (correlation coefficient = 0.578) significantly correlated with that of LG₃₀ on PET/CT (P < 0.05).

Conclusion

CT perfusion parameters including BF and FEP may be used as early predictors of tumor response in patients with liver metastasis from colorectal cancer.     

Usefulness of computerized method for lung nodule detection on digital chest radiographs using similar subtraction images from different patients

Purpose

The purpose of this study is to evaluate the usefulness of a novel computerized method to select automatically the similar chest radiograph for image subtraction in the patients who have no previous chest radiographs and to assist the radiologists’ interpretation by presenting the “similar subtraction image” from different patients.

Materials and methods

Institutional review board approval was obtained, and the requirement for informed patient consent was waived. A large database of approximately 15,000 normal chest radiographs was used for searching similar images of different patients. One hundred images of candidates were selected according to two clinical parameters and similarity of the lung field in the target image. We used the correlation value of chest region in the 100 images for searching the most similar image. The similar subtraction images were obtained by subtracting the similar image selected from the target image. Thirty cases with lung nodules and 30 cases without lung nodules were used for an observer performance test. Four attending radiologists and four radiology residents participated in this observer performance test.

Results

The AUC for all radiologists increased significantly from 0.925 to 0.974 with the CAD (P = .004). When the computer output images were available, the average AUC for the residents was more improved (0.960 vs. 0.890) than for the attending radiologists (0.987 vs. 0.960).

Conclusion

The novel computerized method for lung nodule detection using similar subtraction images from different patients would be useful to detect lung nodules on digital chest radiographs, especially for less experienced readers.     

Imaging differentiation of pathologic fractures caused by primary and secondary bone tumors

Objective

To describe pre-treatment imaging features of pathologic fractures caused by primary bone tumors (PBTs) and metastatic bone tumors (MBTs) and determine if radiographic or cross-sectional features can differentiate the underlying pathologies associated with the fractures.

Methods

Sixty-nine patients with a diagnosis of a pathologic fracture were enrolled. Biopsy established PBT as the cause of the pathologic fracture in 16 (23%) cases and MBT in 53 (77%) cases. The radiographs, computed tomography (CT) scans, and magnetic resonance imaging (MRI) scans of the subjects were retrospectively reviewed for the presence of multiple imaging features.

Results

Compared to pathologic fractures caused by MBTs, the fractures caused by PBTs demonstrated a higher incidence of lytic bone cortex, mineralization and a soft-tissue mass on radiographs, mineralization and a soft-tissue mass on CT scans, and periosteal abnormality on MRI scans (P < 0.01). These features also exhibited a high negative predictive value in supporting the diagnosis of an underlying PBT over MBT.

Conclusion

Pathologic fractures caused by PBT and MBT may be differentiated by a few specific radiographic and CT imaging features, though MRI was poor for characterization of the underlying lesion. Such knowledge may assist radiologists in raising the possibility of a PBT as the cause of a pathologic fracture.     

Angiographic frequency of blunt cerebrovascular injury in patients with carotid canal or vertebral foramen fractures on multidetector CT

Purpose

Blunt carotid injuries (BCI's) and blunt vertebral artery injuries (BVI's), known jointly as BCVI's, are common in “high risk” patients. The purpose is to evaluate the rate of occurrence of BCI/BVI in patients screened purely by the radiologic criteria of fracture through the carotid canal or vertebral transverse foramina, or significant cervical subluxation, noted by multidetector CT.

Methods

Seventy-one patients with 108 catheterized vessels were included over a 13-month interval. The angiographic examinations were prompted by current hospital protocol, solely by the presence of fractures involving/adjacent to the carotid canal, cervical fractures involving/adjacent to the foramen transversarium, or cervical fractures with significant subluxation. The incidence of each grade of blunt injury was calculated after review of the CT scans and catheter angiograms by two neuroradiologists.

Results

Two thousand and seventy-three total blunt trauma admissions occurred during the time period, with a BCVI rate of 0.92–1.0% (depending on the reviewer), similar to previous studies. Mean time to catheter angiography was 16.6 h. Of the 71 included patients, there were 11–12 BCI's and 10–12 BVI's, an overall rate of 27–30% of BCVI in the patients with foraminal fractures. Interobserver agreement in reviewing the catheter angiograms was excellent (Kappa 0.795). Of note, three internal carotid pseudoaneurysms resolved spontaneously after anticoagulation or aspirin.

Conclusion

This study confirms that there is a high rate of BCVI in the presence of carotid canal or vertebral foramen fractures that are noted by multidetector CT. Utilization of purely radiologic criteria of foraminal involvement may be a significant screening tool in the decision of whether to evaluate these patients acutely by catheter or CT angiography, and for early detection of patients at risk for symptomatology, to initiate prompt, prophylactic treatment.     

Hepatic arterial perfusion increases in the early stage of severe acute pancreatitis patients: evaluation by perfusion computed tomography

Purpose

Although hepatic perfusion abnormalities have been reported in patients with acute pancreatitis, hepatic perfusion with severe acute pancreatitis (SAP) has not been quantitatively evaluated in humans. Therefore, we investigated hepatic perfusion in patients with SAP using perfusion CT.

Materials and methods

Hepatic perfusion CT was performed in 67 patients with SAP within 3 days after symptom onset. The patients were diagnosed as having SAP according to the Atlanta criteria. Fifteen cases were established as a control group. Perfusion CT was obtained for 54 s beginning with a bolus injection of 40 ml of contrast agent (600–630 mgI/kg) at a flow rate of 4 ml/s. Perfusion data were analyzed by the dual-input maximum slope method to obtain hepatic arterial perfusion (HAP) and hepatic portal perfusion (HPP). Finally, we compared HAP and HPP in SAP patients with those in the control group, respectively.

Results

Average HAP was significantly higher in SAP patients than in the control group (75.1 ± 38.0 vs. 38.2 ± 9.0 ml/min/100 ml; p < 0.001). There was no significant difference in average HPP between SAP patients and the control group (206.7 ± 54.9 vs. 204.4 ± 38.5 ml/min/100 ml; p = 0.92).

Conclusion

Using quantitative analysis on perfusion CT, we first demonstrated an increase of HAP in the right hepatic lobe in SAP patients.     

Autoimmune pancreatitis: Assessment of the enhanced duct sign on multiphase contrast-enhanced computed tomography

Purpose

To assess the usefulness of the computed tomography (CT) finding of main pancreatic duct (MPD) wall enhancement, termed the “enhanced duct sign”, for diagnosis of autoimmune pancreatitis (AIP) in comparison with diagnosis of pancreatic carcinoma and chronic pancreatitis.

Materials and methods

Two radiologists independently evaluated the presence or absence of the enhanced duct sign on multiphase contrast-enhanced CT in patients with AIP (n = 55), pancreatic carcinoma (n = 50), and chronic pancreatitis (n = 50). The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of AIP were calculated. In patients demonstrating the enhanced duct sign, additional findings were evaluated by consensus.

Results

The enhanced duct sign was more frequently observed in patients with AIP (37/55, 67%) than in patients with pancreatic carcinoma (5/50, 10%) or chronic pancreatitis (0/50, 0%) (P < 0.05). The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of the finding were 0.67, 0.95, 0.85, 0.88, and 0.84, respectively. In AIP, the lumen within the enhanced duct was completely or partially invisible in 29 of 37 (78%) patients, and the enhanced duct was observed within the affected pancreatic parenchyma in 35 of 37 (95%) patients. In pancreatic carcinoma, the lumen within the enhanced duct was visible in all patients (5/5, 100%), and the enhanced duct was observed downstream of the tumor (5/5, 100%).

Conclusion

The enhanced duct sign is highly specific of AIP.     

Comparison of adaptive statistical iterative and filtered back projection reconstruction techniques in brain CT

Purpose

To compare image quality and visualization of normal structures and lesions in brain computed tomography (CT) with adaptive statistical iterative reconstruction (ASIR) and filtered back projection (FBP) reconstruction techniques in different X-ray tube current–time products.

Materials and methods

In this IRB-approved prospective study, forty patients (nineteen men, twenty-one women; mean age 69.5 ± 11.2 years) received brain scan at different tube current–time products (300 and 200 mAs) in 64-section multi-detector CT (GE, Discovery CT750 HD). Images were reconstructed with FBP and four levels of ASIR-FBP blending. Two radiologists (please note that our hospital is renowned for its geriatric medicine department, and these two radiologists are more experienced in chronic cerebral vascular disease than in neoplastic disease, so this research did not contain cerebral tumors but as a discussion) assessed all the reconstructed images for visibility of normal structures, lesion conspicuity, image contrast and diagnostic confidence in a blinded and randomized manner. Volume CT dose index (CTDI_vol) and dose-length product (DLP) were recorded. All the data were analyzed by using SPSS 13.0 statistical analysis software.

Results

There was no statistically significant difference between the image qualities at 200 mAs with 50% ASIR blending technique and 300 mAs with FBP technique (p > .05). While between the image qualities at 200 mAs with FBP and 300 mAs with FBP technique a statistically significant difference (p < .05) was found.

Conclusion

ASIR provided same image quality and diagnostic ability in brain imaging with greater than 30% dose reduction compared with FBP reconstruction technique.     

Pulmonary nodules: effect of adaptive statistical iterative reconstruction (ASIR) technique on performance of a computer-aided detection (CAD) system-comparison of performance between different-dose CT scans

Purpose

To evaluate the effects of ASIR on CAD system of pulmonary nodules using clinical routine-dose CT and lower-dose CT.

Materials and methods

Thirty-five patients (body mass index, 22.17 ± 4.37 kg/m²) were scanned by multidetector-row CT with tube currents (clinical routine-dose CT, automatically adjusted mA; lower-dose CT, 10 mA) and X-ray voltage (120 kVp). Each 0.625-mm-thick image was reconstructed at 0%-, 50%-, and 100%-ASIR: 0%-ASIR is reconstructed using only the filtered back-projection algorithm (FBP), while 100%-ASIR is reconstructed using the maximum ASIR and 50%-ASIR implies a blending of 50% FBP and ASIR. CAD output was compared retrospectively with the results of the reference standard which was established using a consensus panel of three radiologists. Data were analyzed using Bonferroni/Dunn's method. Radiation dose was calculated by multiplying dose-length product by conversion coefficient of 0.021.

Results

The consensus panel found 265 non-calcified nodules ≤30 mm (ground-glass opacity [GGO], 103; part-solid, 34; and solid, 128). CAD sensitivity was significantly higher at 100%-ASIR [clinical routine-dose CT, 71% (overall), 49% (GGO); lower-dose CT, 52% (overall), 67% (solid)] than at 0%-ASIR [clinical routine-dose CT, 54% (overall), 25% (GGO); lower-dose CT, 36% (overall), 50% (solid)] (p < 0.001). Mean number of false-positive findings per examination was significantly higher at 100%-ASIR (clinical routine-dose CT, 8.5; lower-dose CT, 6.2) than at 0%-ASIR (clinical routine-dose CT, 4.6; lower-dose CT, 3.5; p < 0.001). Effective doses were 10.77 ± 3.41 mSv in clinical routine-dose CT and 2.67 ± 0.17 mSv in lower-dose CT.

Conclusion

CAD sensitivity at 100%-ASIR on lower-dose CT is almost equal to that at 0%-ASIR on clinical routine-dose CT. ASIR can increase CAD sensitivity despite increased false-positive findings.     

Multidetector row computed tomography of acute pancreatitis: Utility of single portal phase CT scan in short-term follow up

Objective

The purpose of this study is to evaluate the question of whether nonenhanced CT or contrast enhanced portal phase CT can replace multiphasic pancreas protocol CT in short term monitoring in patients with acute pancreatitis.

Materials and methods

This retrospective study was approved by the Institutional Review Board. From April 2006 to May 2010, a total of 52 patients having acute pancreatitis who underwent initial dual phase multidetector row CT (unenhanced, arterial, and portal phase) at admission and a short term (within 30 days) follow up dual phase CT (mean interval 10.3 days, range 3–28 days) were included. Two abdominal radiologists performed an independent review of three sets of follow up CT images (nonenhanced scan, single portal phase scan, and dual phase scan). Interpretation of each image set was done with at least 2-week interval. Radiologists evaluated severity of acute pancreatitis with regard to pancreatic inflammation, pancreatic necrosis, and extrapancreatic complication, based on the modified CT severity index. Scores of each image set were compared using a paired t-test and interobserver agreement was evaluated using intraclass correlation coefficient statistics.

Results

Mean scores of sum of CT severity index on nonenhanced scan, portal phase scan, and dual phase scan were 5.7, 6.6, and 6.5 for radiologist 1, and 5.0, 5.6, and 5.8 for radiologist 2, respectively. In both radiologists, contrast enhanced scan (portal phase scan and dual phase scan) showed significantly higher severity score compared with that of unenhanced scan (P < 0.05), while portal phase and dual phase scan showed no significant difference each other. The trend was similar regarding pancreatic inflammation and extrapancreatic complications, in which contrast enhanced scans showed significantly higher score compared with those of unenhanced scan, while no significant difference was observed between portal phase scan and dual phase scan. In pancreatic necrosis analysis, there was no significant difference between the three image sets for both radiologists. However, when only the patients having pancreatic necrosis (n = 13) was separately analyzed, significant differences were observed between the unenhanced and portal phase scan (P = 0.04, for radiologist 1), or unenhanced and dual phase scan (P = 0.013, for radiologist 2).

Conclusion

For short-term follow up imaging in assessment of patients with acute pancreatitis, single portal phase CT images without adding unenhanced or arterial phase images provide sufficient information, and thereby reduce radiation exposure.     

Multidetector computed tomography arthrography of the knee: diagnostic accuracy and indications

Purpose

To evaluate the diagnostic accuracy and indications of arthrography with multidetector computed tomography (arthro-MDCT) of the knee, in patients with absolute or relative contraindications to MRI and in patients with periarticular metal implants using diagnostic arthroscopy as the gold standard.

Materials and methods

After intra-articular injection of iodixanol and volumetric acquisition, 68 knees in patients of both sexes (30 females, 38 males, age range 32–60 years) were examined with a 16-detector-row CT scanner. The patients had arthralgia but no radiologically detected fractures. They could not be studied by MRI either because of absolute contraindications (subcutaneous electronic implants), surgical metal implants or claustrophobia. In 37 of 68 patients who had had previous knee surgery, the arthro-CT examination was preceded by an MRI on the same day.All examinations were interpreted by two experienced musculoskeletal radiologists.The findings were compared with arthroscopic findings carried out within 28 days of the CT study.

Results

In non-operated patients the comparison between arthro-MDCT and arthroscopy showed sensitivity and specificity ranging between 86% and 100%. In the 37 operated knees, arthro-MDCT had an accuracy of 95% compared with 53% of the MRI.Inter-observer agreement was almost perfect (K = 0.97) in the evaluation of all types lesions, both on MDCT and MRI.When arthro-MDCT was compared with MRI in post-operative patients by a McNemar test, a significant difference (p < 0.05) was found between these two techniques.

Conclusions

Arthro-MDCT of the knee is a safe technique that provides accurate diagnosis in identifying chondral, fibrocartilaginous and intra-articular ligamentous lesions, in patients that cannot be evaluated by MRI, and in patients after surgical.     

Evaluation of the sensitivity of scout radiographs on unenhanced helical CT in identifying ureteric calculi: a large UK tertiary referral centre experience

Objective

Unenhanced helical CT for kidney, ureter and bladder (CT KUB) has become the standard investigation for renal colic. This study aims to determine the sensitivity of scout radiographs in detecting ureteric calculi using CT KUB as a standard reference.

Methods

A retrospective review of consecutive patients who presented with acute flank pain and were investigated using CT KUB. 201 patients with positive ureteric calculi were included. Two radiologists independently reviewed the scout radiographs with access to CT KUB images. Each observer recorded the presence or absence of calculi, location, size and mean Hounsfield units of each calculus.

Results

203 ureteric calculi were analysed from 201 patients. The overall sensitivity of scout radiographs for Observer A was 42.3% and for Observer B 52.2%, with an interobserver reliability κ-value of 0.78. The significance of mean Hounsfield units and size between two groups of patients with visible stones and those not visible were tested; the p-value for both variables was <0.0001, which is statistically significant. The study found that calculi in the upper ureter and larger than 4 mm are more likely to be seen on the scout radiograph.

Conclusions

Usage of CT scout radiography should be encouraged and reported routinely in conjunction with CT KUB as a baseline for treatment follow-up.Unenhanced helical CT for kidney, ureter and bladder (CT KUB) has become the standard investigation for renal colic [1,2]. Its superior sensitivity and specificity has led to the demise in popularity of intravenous urogram (IVU) [3-5], although there remain some concerns about radiation dose [6]. At our institution, CT KUB has been the first-line investigation for patients suspected of having acute renal colic since 2006 [7]. Serial plain abdominal radiographs (KUB) however remain useful baseline and follow-up investigations to track the passage of stones unless the calculi are radiographically occult, in which case CT KUB or ultrasound will then be the investigations of choice.Digital CT scout radiographs are produced routinely to assist in positioning patients before axial images are acquired. They are taken from the level of the xiphoid sternum to the level of the pubic symphysis. The scout view is often overlooked and deemed not to be of diagnostic quality. However it has been proposed that careful study of the scout radiograph may identify the calculus and negate the need for a baseline plain abdominal KUB radiograph [8].In our institution, only a small number of patients who had ureteric calculi diagnosed on CT KUB had baseline plain radiographs at the same clinical presentation; the timing of the baseline plain KUB radiographs taken differs depending on varying urologists'' clinical practices. This has posed a real clinical dilemma as the absence of calculi on follow-up plain KUB taken several days after the initial presentation could be due either to the successful passage of calculi or to a radiographically occult stone. As a consequence, repeat CT KUB is occasionally performed in order to clarify the position of the calculi. We postulate that, if scout radiographs have sufficient sensitivity to detect calculi, they can be reported in conjunction with all the CT KUB examinations and patients will have a clear follow-up pathway with either plain KUB or ultrasound at the time of presentation.Although there are several recently published series that evaluate the sensitivity of scout radiographs, the number of patients used was relatively small [8-11]. The primary aim of this study was to determine the sensitivity of CT KUB scout radiographs in detecting ureteric calculi using CT KUB as a standard reference and comparing this against the recently published series. Factors that may affect the sensitivity of detection on scout radiographs will be evaluated. The secondary end point was to assess the sensitivity of plain radiographs in detecting ureteric calculi compared with scout radiographs using CT KUB as the gold standard. The potential saving on the cost of plain radiographs and radiation dose will be discussed.