Conventional Dose CT Research Articles

Abstract PO5-05-13: Clinical utility of whole body low dose computed tomography for detecting bone metastasis in breast cancer patients: A cross sectional study

Abstract Clinical utility of Whole Body Low Dose CT scan for detecting bone metastasis in Breast cancer patients: A cross sectional study Background: Skeletal scintigraphy (Bone scan) is the imaging of choice to detect bone metastasis in locally advanced and metastatic breast cancer patients. Nuclear medicine facilities are however limited in their availability. As an alternative diagnostic modality to bone scan, we studied the diagnostic capability of Whole-Body Low Dose CT (WBLDCT) scan for detection of bone metastasis in these patients. Materials and Method: This cross-sectional study was conducted from November 2021 to May 2023 at a tertiary healthcare center in India with an aim to study the clinical applicability of whole-body low dose computed tomography scan for detecting bone metastasis in patients with breast cancer. Breast cancer patients with primary tumor measuring 5cm or more, pathologically proven axillary lymph node metastasis, Stage III/IV disease, symptoms attributable to metastasis and suspected disease recurrence were included. All patients underwent WBLDCT and Bone scan within a period of about 2 weeks. WBLDCT was done during the same time as conventional dose CT scan was being done as part of metastatic workup. WBLDCT acquisition protocol was set in CT scan machine by modulating the technical parameters like Care dose 4D-automated, Care kV semi, rotation time & noise index. The image analysis was performed by Radiologist and Nuclear medicine experts in a blinded fashion. Data was recorded in MS Excel sheet. Sensitivity, specificity, positive and negative predicative value, and concordance rates were calculated using SPSS software ver 25.0. Agreement amongst WBLDCT and Bone scan was calculated using Inter-rater agreement. p value < 0.05 was taken as significant. Results: 110 patients were enrolled in this study. The mean age of participants was 48.5 years and three fourth had stage III disease at presentation. Estrogen receptor positive disease was seen in 43.64% participants while 30% were triple negative. Her2neu positive disease was seen in 27.27% patients. Bone scan couldn’t be done in 03 patients who deferred treatment (these had no bone metastasis on WBLDCT). Both bone scan and WBLDCT detected bone metastasis in 19 patients. Bone scan picked up additional metastasis in three patients which were missed on WBLDCT. WBLDCT detected bone metastasis additionally in three patients which were not detected on Bone scan. Multiple lesions were most seen in vertebrae in 38.5% and 28.6% on bone scan and WBLDCT respectively. The sensitivity and specificity of WBLDCT for detection of bone metastasis was 86.36% and 96.47% respectively. The concordance rate between Bone scan and WBLDCT scan was 94.39% with an Inter-rater Kappa(k) quotient for agreement of 0.828 (p< 0.0001). Conclusion: WBLDCT scan has comparable diagnostic capability to skeletal scintigraphy in detecting bone metastasis in breast cancer and may be a useful alternative specially in resource limited settings. Table 1: Sensitivity, specificity, positive predictive value and negative predictive value of WBLDCT for detection of metastasis Variables Values Sensitivity (95% CI) 86.36% Specificity (95% CI) 96.47% AUC (95% CI) 0.91 Positive Predictive Value (95% CI) 86.36% Negative Predictive Value (95% CI) 96.47% Diagnostic accuracy 94.39% Inter-rater agreement (kappa) 0.828 Citation Format: Lipton Mitra, Suhani Suhani, Ankur Goyal, Rakesh Kumar, Mohit Joshi, Hemanga Bhattacharjee, Haresh KP, Raju Sharma, Rajinder Parshad. Clinical utility of whole body low dose computed tomography for detecting bone metastasis in breast cancer patients: A cross sectional study [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-05-13.

A comparative study on the use of ultra-low dose computed tomography scans with conventional computed tomography scans for the evaluation of proximal tibia intra-articular fractures

PurposeA rise in the need of preoperative CT assessment of proximal tibial intra-articular fractures has given rise to an increased load of radiation exposure. This comparative study aims at assessing the efficacy of low dose CT scan by collating images of tibial plateau fractures produced by low dose CT scan with that of conventional dose CT scan. Furthermore, the study aims at computing the comprehensive reduction in the effective dosage of radiation when low dose CT scan is employed for assessing these fractures. MethodsThe study comprise of 23 cases of proximal tibial intra-articular fractures (confirmed by initial radiographs). Low-dose CT scan of the injured limb was preceded by conventional dose CT scan for generating images that were assessed and reported independently by five (single blinded) radiologists (using Schatzker's CT based classification). Quantification of fracture was done to compare them statistically. ResultsA sensitivity of 93.94 % and positive predictive value of 93.92 % was observed on comparing images from low dose and conventional dose CT scan. An effective reduction of 89.81 % in overall dosage of radiation exposure was observed. ConclusionNear equal quality images were generated by low dose CT scan as compared to conventional dose CT scan, thereby demonstrating its non-inferiority with an effective reduction of 89.81 % in overall dosage of radiation exposure.

The diagnostic performance of ultra-low-dose 320-row detector CT with different reconstruction algorithms on limb joint fractures in the emergency department.

The aim of the study was to evaluate whether ultra-low-dose computed tomography (ULD-CT) could replace conventional-dose CT (CD-CT) for diagnosis of acute wrist, ankle, knee, and shoulder fractures in emergency departments (ED). We developed CD-CT and ULD-CT scanning schemes for the various joints of the four limbs and scanned emergency patients prospectively. When performing CD-CT, a conventional bone reconstruction algorithm was used, while ULD-CT used both soft tissue and bone algorithms. A five-point scale was used to evaluate whether ULD-CT image quality affected surgical planning. The image quality and diagnostic performance of different types of scanned and reconstructed images for diagnosing fractures were evaluated and compared. Effective radiation dose of each group was calculated. Our study included 56 normal cases and 185 fracture cases. The combination of bone and soft tissue algorithms on ULD-CT can improve diagnostic performance, such that on ULD-CT, the sensitivity improved from 96.7% to 98.9%, specificity from 98.2% to 100%, positive predictive value from 99.4% to 100%, negative predictive value from 90.2% to 96.6% and diagnostic accuracy ranged from 97.5% to 99.1%. There were no statistically significant differences between ULD-CT and CD-CT on diagnostic performance (p values, 0.40-1.00). The radiation doses for ULD-CT protocols were only 3.0-7.7% of those for CD-CT protocols (all p < 0.01). In the emergency department, the 320-row detector ULD-CT could replace CD-CT in the diagnosis of limb joint fractures. The combination of bone algorithm with soft tissue algorithm reconstruction can further improve the image quality and diagnostic performance.

Reproducibility of radiomic features of pulmonary nodules between low-dose CT and conventional-dose CT

The reproducibility of radiomic features is essential to lung cancer detection. This study aimed to investigate the reproducibility of radiomic features of pulmonary nodules between low-dose computed tomography (LDCT) and conventional-dose computed tomography (CDCT). A total of 105 patients with 119 pulmonary nodules [39 ground-glass nodules (GGNs) and 80 solid nodules] who underwent LDCT and CDCT were retrospectively studied between September 2019 and November 2020. Pulmonary nodules were manually segmented and 1,125 radiomic features (shape, first-order intensity, texture, wavelet, and Laplacian of the Gaussian features) were extracted from both LDCT and CDCT images. The concordance correlation coefficient (CCC) was used to evaluate the reproducibility of these radiomic features. Of the 1,125 radiomic features considered, 35.5% (399 of 1,125) and 41.5% (467 of 1,125) were reproducible (CCC ≥0.85) for GGNs and solid nodules, respectively. The intensity, texture, and wavelet features of solid nodules were more reproducible than those of GGNs. The mean CCC values for intensity and texture features of solid nodules were of 0.85 and above, whereas the mean values for those of GGNs were of less than 0.85. After Gaussian kernel (σ =2) preprocessing, the CCC of intensity and texture features of GGNs improved from 0.77 to 0.90, and 84.9% (79 of 93) of the radiomic features were reproducible (mean CCC increase from 0.84±0.13 to 0.92±0.08 for intensity features, and from 0.75±0.15 to 0.89±0.11 for texture features). Wavelet features had the lowest CCCs for both GGNs and solid nodules. The majority of the radiomic feature classes of solid pulmonary nodules have a high level of reproducibility between LDCT and CDCT. However, LDCT should not be used as an alternative to CDCT in the radiomic study of GGNs.

Artificial Intelligence-Aided Diagnosis Software to Identify Highly Suspicious Pulmonary Nodules.

IntroductionTo evaluate the value of artificial intelligence (AI)-assisted software in the diagnosis of lung nodules using a combination of low-dose computed tomography (LDCT) and high-resolution computed tomography (HRCT).MethodA total of 113 patients with pulmonary nodules were screened using LDCT. For nodules with the largest diameters, an HRCT local-target scanning program (combined scanning scheme) and a conventional-dose CT scanning scheme were also performed. Lung nodules were subjectively assessed for image signs and compared by size and malignancy rate measured by AI-assisted software. The nodules were divided into improved visibility and identical visibility groups based on differences in the number of signs identified through the two schemes.ResultsThe nodule volume and malignancy probability for subsolid nodules significantly differed between the improved and identical visibility groups. For the combined scanning protocol, we observed significant between-group differences in subsolid nodule malignancy rates.ConclusionUnder the operation and decision of AI, the combined scanning scheme may be beneficial for screening high-risk populations.

Appendiceal Visualization on 2-mSv CT vs. Conventional-Dose CT in Adolescents and Young Adults with Suspected Appendicitis: An Analysis of Large Pragmatic Randomized Trial Data.

ObjectiveWe compared appendiceal visualization on 2-mSv CT vs. conventional-dose CT (median 7 mSv) in adolescents and young adults and analyzed the undesirable clinical and diagnostic outcomes that followed appendiceal nonvisualization.Materials and MethodsA total of 3074 patients aged 15–44 years (mean ± standard deviation, 28 ± 9 years; 1672 female) from 20 hospitals were randomized to the 2-mSv CT or conventional-dose CT group (1535 vs. 1539) from December 2013 through August 2016. A total of 161 radiologists from 20 institutions prospectively rated appendiceal visualization (grade 0, not identified; grade 1, unsure or partly visualized; and grade 2, clearly and entirely visualized) and the presence of appendicitis in these patients. The final diagnosis was based on CT imaging and surgical, pathologic, and clinical findings. We analyzed undesirable clinical or diagnostic outcomes, such as negative appendectomy, perforated appendicitis, more extensive than simple appendectomy, delay in patient management, or incorrect CT diagnosis, which followed appendiceal nonvisualization (defined as grade 0 or 1) and compared the outcomes between the two groups.ResultsIn the 2-mSv CT and conventional-dose CT groups, appendiceal visualization was rated as grade 0 in 41 (2.7%) and 18 (1.2%) patients, respectively; grade 1 in 181 (11.8%) and 81 (5.3%) patients, respectively; and grade 2 in 1304 (85.0%) and 1421 (92.3%) patients, respectively (p < 0.001). Overall, undesirable outcomes were rare in both groups. Compared to the conventional-dose CT group, the 2-mSv CT group had slightly higher rates of perforated appendicitis (1.1% [17] vs. 0.5% [7], p = 0.06) and false-negative diagnoses (0.4% [6] vs. 0.0% [0], p = 0.01) following appendiceal nonvisualization. Otherwise, these two groups were comparable.ConclusionThe use of 2-mSv CT instead of conventional-dose CT impairs appendiceal visualization in more patients. However, appendiceal nonvisualization on 2-mSv CT rarely leads to undesirable clinical or diagnostic outcomes.

Low-Dose Abdominal CT for Evaluating Suspected Appendicitis in Adolescents and Young Adults: Review of Evidence.

Due to its excellent diagnostic performance, CT is the mainstay of diagnostic test in adults with suspected acute appendicitis in many countries. Although debatable, extensive epidemiological studies have suggested that CT radiation is carcinogenic, at least in children and adolescents. Setting aside the debate over the carcinogenic risk of CT radiation, the value of judicious use of CT radiation cannot be overstated for the diagnosis of appendicitis, considering that appendicitis is a very common disease, and that the vast majority of patients with suspected acute appendicitis are adolescents and young adults with average life expectancies. Given the accumulated evidence justifying the use of low-dose CT (LDCT) of only 2 mSv, there is no reasonable basis to insist on using radiation dose of multi-purpose abdominal CT for the diagnosis of appendicitis, particularly in adolescents and young adults. Published data strongly suggest that LDCT is comparable to conventional dose CT in terms of clinical outcomes and diagnostic performance. In this narrative review, we will discuss such evidence for reducing CT radiation in adolescents and young adults with suspected appendicitis.

Conventional-Dose CT Versus 2-mSv CT for Right Colonic Diverticulitis as an Alternate Diagnosis of Appendicitis: Secondary Analysis of Large Pragmatic Randomized Trial Data.

BACKGROUND. Adoption of low-dose CT for the diagnosis of appendicitis has been slow in children and in adults, partly because of concern about missing alternative diagnoses including right colonic diverticulitis. OBJECTIVE. The purpose of our study was to retrospectively compare the diagnostic performance of IV contrast-enhanced 2-mSv and conventional-dose CT (CDCT) for the diagnosis of right colonic diverticulitis in adolescents and young adults with suspected appendicitis. METHODS. This post hoc analysis of a prospective randomized controlled trial included 3074 patients (1672 female patients and 1402 male patients) ranging in age from 15 to 44 years old (mean ± SD, 28 ± 9 years) from 20 hospitals. From December 2013 to August 2016, patients were randomized to either the 2-mSv CT group (n = 1535 patients) or the CDCT (median, 7 mSv) group (n = 1539 patients). A total of 161 radiologists prospectively issued CT reports in which they suggested alternative diagnoses for 976 (2-mSv CT) and 924 (CDCT) patients. Seven independent assessors adjudicated final diagnoses on the basis of clinical and CT findings. Endpoints of test-positives, test-negatives, sensitivity, and specificity for right colonic diverticulitis were compared using chi-square and Mann-Whitney U tests. Characteristics and disposition of patients with test-positive results were assessed. Four readers retrospectively reviewed CT images of 400 patients selected from the trial (113 and 108 patients with diverticulitis from 2-mSv CT and CDCT groups, respectively) to evaluate interobserver agreement for right colonic diverticulitis in terms of Gwet coefficients. RESULTS. Between-group differences were minute for most endpoints related to right colonic diverticulitis: test-positives (difference, 0.2% [95% CI, -1.8% to 2.1%]; 7.8% [119/1535 patients] vs 7.6% [117/1539 patients]; p = .93), test-negatives (0.5% [95% CI, -1.5% to 2.5%]; 91.7% [1407/1535] vs 91.2% [1403/1539]; p = .67), sensitivity (0% [95% CI, -6% to 6%]; 95% [110/116] vs 95% [105/111]; p > .99), and specificity (0.3% [95% CI, -0.5% to 0.9%]; 99.4% [1401/1410] vs 99.1% [1397/1409]; p = .66). The characteristics and disposition of test-positive patients were similar between the two groups. Gwet coefficients were high and comparable between the two groups (2-mSv CT vs CDCT, 0.849 vs 0.889; p = .20). CONCLUSION. Two-millisievert CT is comparable to conventional-dose CT for the diagnosis of right colonic diverticulitis. CLINICAL IMPACT. By mitigating concern about a missed diagnosis of right colonic diverticulitis, the results further support the use of low-dose CT in patients with suspected appendicitis. TRIAL REGISTRATION. ClinicalTrials.gov NCT01925014.

Advantages of Application of Whole-Body Low-Dose Computed Tomography in Multiple Myeloma

Aim: This study was designed to investigate the application of whole-body low-dose computed tomography in the examination of multiple myeloma. Method: 40 patients with multiple myeloma admitted to our hospital were prospectively selected as the study subjects. All patients were pathologically confirmed and/or clinically diagnosed with multiple myeloma. Patients were randomly divided into two groups: Group A (n=20) received whole-body lowdose CT scan with SAFIR iterative reconstruction algorithm; Group B (n=20) underwent whole body conventional dose CT scan combined with conventional reconstruction algorithm. The image quality was scored subjectively, and the objective evaluation indexes (including CT value and noise of neck, chest, abdomen, pelvic cavity and lower extremities, signal-to-noise ratio and image quality index) were measured and recorded, and the radiation dose was recorded. Mann-Whitney U test (to evaluate the subjective score) and t test (to evaluate the objective evaluation index and radiation dose) were used to compare the differences of the above indexes between group A and group B. Result: All the images met the diagnostic requirements. There was no statistical significance in the scores between group A and group B (P&gt;0.05). Significant differences in CT value, noise and SNR of neck, chest, abdomen, pelvis and lower extremities between group A and group B (P&lt;0.05) were identified. For the image quality index (figure of merit, FOM), the FOM of chest, abdomen and pelvis was not statistically significantly changed (P&lt;0.05). The radiation dose of group A decreased by 56.77% (3.06/5.39) compared to group B with a statistically significant difference (P&lt;0.05). The Kappa values of subjective scores of the two groups showed no statistically significant difference (respectively, 0.68 and o.69, P&gt;0.05). Conclusion: Compared to conventional CT examination, whole-body lowdose CT scan combined with SAFIR iterative reconstruction algorithm can effectively reduce noise, reduce X-ray radiation dose, and obtain ideal image quality in multiple myeloma examination, which has a certain application value.

Optimal threshold in low-dose CT quantification of emphysema

ObjectiveLow–dose CT is now widely used in the screening of lung cancer and the detection of pulmonary nodules. There has also been increasing interest in using Low–dose CT for evaluating emphysema. In conventional dose CT, the threshold of −950HU is a common threshold for density-based emphysema quantification for worldwide population. However, the optimal threshold for assessing emphysema at low-dose CT has not been determined. The purpose of this study is to determine the optimal threshold for low-dose CT quantification of emphysema for Chinese population. Materials and methodsIn this study, 548 low-dose chest CT examinations acquired from different subjects (119 none, 49 mild, 163 moderate, 152 severe, and 65 very severe obstruction) are collected. At the level of the entire lung and individual lobes, the extent of emphysema was quantified by the percentage of the low attenuation area (LAA%) at a wide range of thresholds from −850HU to −1000HU. Both Pearson and Spearman’s rank correlation coefficients were used to assess the correlations between 1) LAA% and pulmonary functions and 2) LAA% and the five-category classification. The statistical significance of the difference between correlation coefficients were evaluated using Steiger’Z test. ResultsLAA% had a good correlation with both pulmonary function (|r| = 0.1–0.600, p < 0.001) and the five-category classification (r = 0.163–0.602, p < 0.001) in both the entire lung and individual lobes under different thresholds. The highest correlation coefficient is obtained at −940HU instead of -950HU. ConclusionLow-dose CT can be used for quantitative assessment of emphysema, and the threshold of -940HU is a suitable threshold for quantifying emphysema in low-dose CT images for Chinese population.

Lung nodules assessment in ultra-low-dose CT with iterative reconstruction compared to conventional dose CT.

To retrospectively assess whether the low-voltage lung CT scan coupled with iterative reconstruction algorithms can be an optimal scanning method for measuring the size and density of lung nodules in cancer patients. Eighty two cancer patients receiving both chest scan with low-voltage (80 kV) and abdomen CT scan with standard voltage (120 kV) were enrolled in this study. Lung nodules were measured manually and semi-automatically by two different computer-aided diagnosis (CAD) systems. The nodules were then divided into large-, medium- and small-size groups based on their largest diameter. Additionally, the nodules were categorized into three different groups according to their density: calcified, solid and partial-solid nodules. The 3D volumes, average diameter and CT value of lung nodules were measured using the two CAD semi-automated systems, and the CT values were compared with regards to the different tube voltages. Furthermore, the accuracy and reliability of CAD systems were validated in the large nodules. The scores of subjective evaluation indicated that the quality of lung nodule images yielded optimal clinical diagnostic value for both 80 kV (2.35±0.054) and 120 kV (2.51±0.053) scanning methods, with a strong inter-observer consistency (Kappa =0.848 and 0.829, respectively). Intraclass correlation coefficient (ICC) and Bland-Altman plot revealed that two CAD systems produced the consistent results. Mean CT values of large nodules (n=18) were significantly different between 80 and 120 kV (-28.11±47.39 vs. -39.61±43.32 HU, P<0.05). Notably, the CT value of 80 kV was 33.96% higher than that of 120 kV. Moreover, the volumes of 66 solid lung nodules demonstrated a statistically significant difference (1.68%) between 80 kV group (740.89±156.97 mm3) and 120 kV group (753.48±157.92 mm3, P<0.05). Furthermore, significant differences were observed in the CT values of large nodules between 80 and 120 kV groups (25.64±12.67 vs. 13.89±9.78 HU, P<0.05), but not the maximum diameters (12.08±1.56 vs. 12.13±1.56 mm, P>0.05). Our study suggests that detection of lung nodules with ultra-low-dose CT can yield an excellent image quality and optimal diagnostic values as compared to the standard dose CT. Therefore, CT scan with low voltage of 80 kV CT scan can be leveraged to improve the diagnosis and surveillance of lung nodules measured less than 30 mm in diameter. Further investigation with a larger sample size is warranted to confirm our findings, particularly the increased CT values of large nodules and the greater volume of solid nodules after exposure to low-dose CT scan.

Low-dose CT with adaptive statistical iterative reconstruction for evaluation of urinary stone.

PurposeTo prospectively determine the diagnostic performance of low-dose CT (LDCT) with adaptive statistical iterative reconstruction (ASIR) technique for the detection of urinary stone disease.ResultsThe average DLP and ED was 408.16 ± 119.04 mGy and 6.12 ± 1.79 mSv in CDCT, and 138.19 ± 76.87 mGy and 2.07 ± 1.15 mSv in LDCT, respectively. The dose reduction rate of LDCT was nearly 66.1% for both DLP and ED (P < 0.05). LDCT–80% ASIR images showed great image quality (mean score = 4.09), which was similar to CDCT-FBP images (mean score = 4.17) (P > 0.05), but higher than LDCT-FBP images (mean score = 2.77) (P < 0.05).Materials and Methods70 consetutive patients with clinically suspected urolithiasis underwent non-enhanced CT. Followed by both conventional-dose CT (CDCT) and low-dose CT (LDCT) scans. Automatic tube current modulation (ATCM) scanning was used, with a noise index setting of 13 in CDCT and 25 in LDCT. Reconstructions were performed with filtered back projection (FBP) and different settings of adaptive statistical iterative reconstruction [ASIR(40%, 60%, 80%)]. Urinary calculi (size, location, number), image quality (scale 1–5), image noise (scale 1–3) and diagnostic confidence levels (scale 1–3) were evaluated and measured by two radiologists independently. Radiation dose was recorded by calculating dose length product (DLP) and effective dose (ED). Statistical analyses included Mann-Whitney U test and Paired t tests.ConclusionsLDCT with ASIR can reduce the radiation dose while maintain relatively high image quality in the diagnosis of urinary stone diseases.

Consensus Recommendations from the Spanish Germ Cell Cancer Group on the Use of High-dose Chemotherapy in Germ Cell Cancer

BackgroundHigh-dose chemotherapy (HDCT) has been studied in several clinical scenarios in advanced germ cell cancer (GCC). ObjectiveTo establish a clinical practice guideline for HDCT use in the treatment of GCC patients. Design, setting, and participantsAn expert panel reviewed information available from the literature. The panel addressed relevant issues concerning and related to HDCT. The guideline was externally reviewed by two international experts. Results and limitationsThe efficacy of HDCT has been demonstrated in selected GCC patients. The most conclusive evidence comes from retrospective analyses that need to be interpreted with caution. HDCT can cure a significant proportion of heavily treated GCC patients. When indicated, sequential HDCT with regimens containing carboplatin and etoposide, as well as peripheral stem-cell support, is recommended. There is no conclusive evidence to recommend HDCT as first-line therapy. According to a multinational retrospective pooled analysis, HDCT might be superior to conventional CT as first salvage treatment in selected patients. There is an urgent need for prospective clinical trials addressing the value of HDCT in GCC patients who experience failure on first-line cisplatin-based CT. In patients who progress on conventional-dose salvage CT, HDCT should be considered. Treatment of these patients at experienced centers is strongly recommended. ConclusionsIt has been demonstrated that HDCT cures selected GCC patients who experience disease progression on conventional rescue regimens. The panel recommends the inclusion of GCC patients in randomized clinical trials including HDCT. Patient summaryThis consensus establishes clinical practice guidelines for the use and study of high-dose chemotherapy in patients with germ cell cancer.

The role of pure iterative reconstruction in conventional dose CT enterography.

Pure iterative reconstruction (Pure IR) has been proposed as a solution to improve diagnostic quality of low dose CT images. We assess the performance of model based iterative reconstruction (MBIR) in improving conventional dose CT enterography (CTE) images. 43 Crohn's patients (27 female) (38.5 ± 12.98 years) referred for CTE were included. Images were reconstructed with pure IR (MBIR, General Electric Healthcare) in addition to standard department protocol (reconstructed with hybrid iterative reconstruction (Hybrid IR) [60% filtered back projection/40% adaptive statistical IR (General Electric Healthcare)]. Image quality was assessed objectively and subjectively at 6 anatomical levels. Clinical interpretation was undertaken in consensus by 2 blinded radiologists along with 2 non-blinded readers ('gold standard'). Results were analyzed using Statistical Package for Social Scientists. Mean effective radiation dose was 6.05 ± 2.84 mSv (size specific dose estimates 9.25 ± 2.9 mGy). Objective and subjective assessment yielded 6106 data points. Pure IR images significantly outperformed those using standard reconstruction techniques across all subjective (p < 0.001 for all comparisons) (noise, contrast resolution, spatial resolution, streak artifact, axial diagnostic acceptability, coronal diagnostic acceptability) and objective (p < 0.004) (noise, signal-to-noise ratio) parameters. Clinical reads of the pure IR images agreed more closely with the gold standard reads than the hybrid IR image reads in terms of overall Crohn's activity grade (κ = 0.630, 0.308) and detection of acute complications (κ = 1.0, 0.896). Results were comparable for bowel wall disease severity assessment (κ = 0.523, 0.593). Pure IR considerably improves image quality of conventional dose CTE images and therefore its use should be expanded beyond low dose protocols to improving image quality at conventional dose CT imaging.

2204 LOW DOSE CT SCAN YIELDS EQUIVALENT STONE MEASUREMENTS WHEN COMPARED TO STANDARD CT SCAN WITH LARGE REDUCTIONS IN RADIATION EXPOSURE

You have accessJournal of UrologyImaging/Radiology: Uroradiology1 Apr 20112204 LOW DOSE CT SCAN YIELDS EQUIVALENT STONE MEASUREMENTS WHEN COMPARED TO STANDARD CT SCAN WITH LARGE REDUCTIONS IN RADIATION EXPOSURE William Sohn, Phillip Mucksavage, Nickul Jain, Elspeth Mcdougall, Allen Cohen, and Ralph Clayman William SohnWilliam Sohn Orange, CA More articles by this author , Phillip MucksavagePhillip Mucksavage Orange, CA More articles by this author , Nickul JainNickul Jain Orange, CA More articles by this author , Elspeth McdougallElspeth Mcdougall Orange, CA More articles by this author , Allen CohenAllen Cohen Orange, CA More articles by this author , and Ralph ClaymanRalph Clayman Orange, CA More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2011.02.2444AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Non-contrast computed tomography is a vital tool in the evaluation of urolithiasis; however, there is concern that the cumulative radiation effects of these scans may be clinically significant. Recent urolithiasis literature has explored the option of low radiation dose CT scans, in hopes of maintaining the benefits of full dose computed tomography, while minimizing the radiation exposure. Since stone size and density are critical in determining the proper treatment modality, it is important to ascertain the reliability of the low dose scan to report necessary data as compared to the standard dose. In a retrospective review, we clinically examined if there were marked differences in stone characteristics between the low-dose CT versus the standard CT scan. METHODS Seven patients seen in the emergency room over a mean of 23 days (range 3 to 51 days) had both a conventional scan and a low-dose scan for the same stone. Radiation dose reduction was calculated based on the patient's body mass index. CT scans were performed with 2 mm section cuts, and 3-D reconstruction was performed to obtain coronal views. These images were then randomized and reviewed by both a urology resident and staff radiologist. The identical stone was measured on both scans. Size of the stones were measured (height, width, and length), and Hounsfield units were calculated using PACS system software (Agfa). RESULTS There was no difference in stone size between the two dosage levels, as measured in height, width, length, or volume of the stone (p values 0.99, 0.94, 0.80, and 0.97 respectively). In addition, no difference in Hounsfield units was appreciated between the two scans (p = 0.90). Between the two scans, there was an average effective dose reduction of 68% from 26.6 mSv to 7.2 mSv (p = 0.008). CONCLUSIONS There was no significant difference in the measurement of size or in Hounsfield units between a low dose and conventional dose CT scan. However, there was an average of 68% reduction in the radiation dose with the low dose protocol. Low dose CT scans can be reliably used to characterize urinary stones and to aid in determining treatment modality while markedly limiting radiation exposure. © 2011 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 185Issue 4SApril 2011Page: e884 Advertisement Copyright & Permissions© 2011 by American Urological Association Education and Research, Inc.MetricsAuthor Information William Sohn Orange, CA More articles by this author Phillip Mucksavage Orange, CA More articles by this author Nickul Jain Orange, CA More articles by this author Elspeth Mcdougall Orange, CA More articles by this author Allen Cohen Orange, CA More articles by this author Ralph Clayman Orange, CA More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Detection of lung nodules with low-dose spiral CT: comparison with conventional dose CT

目的 通过对肺结节模型进行低剂量和常规剂量CT扫描,评价低剂量CT对肺内结节的检出率,分析影响低剂量CT肺结节检出率的因素.方法用包绕水囊的绷带卷模拟肺及胸廓,面粉、黄油及固体石蜡按一定比例制作成CT值-10～50 HU的结节,直径为10和5 mm.分别进行常规剂量(240 mA、140 kV)及3组低剂量扫描(43 mA、140 kV;50 mA、120 kV;75 mA、80 kV)扫描,低剂量各组分别以螺距1.0、1.5、2.0扫描.比较不同剂量、不同螺距组之间的差别.将不同X线剂量模型CT扫描图像与正常成人胸部图像融合,由3名医师在不知模型结节的情况下分别读片,统计肺内结节的检出率和假阳性、假阴性率.分析扫描剂量、螺距对其检出率的影响.结果低剂量扫描对肺内10 mm及5 mm结节的检出率分别为100%、89.7%,与常规剂量组之间的差异无显著性意义(χ2=0.6907,P>0.70).增加螺距导致5 mm的结节检出率下降.结论低剂量CT对肺内直径10 mm和5 mm结节的检出率与常规剂量CT无差别.增大螺距导致肺内结节的密度及边缘的清晰度下降,结节检出率也相应下降。