Imaging Review of Gastrointestinal Motility Disorders.

The motor function of the gastrointestinal tract relies on the enteric nervous system, which includes neurons spanning from the esophagus to the internal anal sphincter. Disorders of gastrointestinal motility arise as a result of disease within the affected portion of the enteric nervous system and may be caused by a wide array of underlying diseases. The etiology of motility disorders may be primary or due to secondary causes related to infection or inflammation, congenital abnormalities, metabolic disturbances, systemic illness, or medication-related side effects. The symptoms of gastrointestinal dysmotility tend to be nonspecific and may cause diagnostic difficulty. Therefore, evaluation of motility disorders requires a combination of clinical, radiologic, and endoscopic or manometric testing. Radiologic studies including fluoroscopy, CT, MRI, and nuclear scintigraphy allow exclusion of alternative pathologic conditions and serve as adjuncts to endoscopy and manometry to determine the appropriate diagnosis. Additionally, radiologist understanding of clinical evaluation of motility disorders is necessary for guiding referring clinicians and appropriately imaging patients. New developments and advances in imaging techniques have allowed improved assessment and diagnosis of motility disorders, which will continue to improve patient treatment options. Online supplemental material is available for this article. ©RSNA, 2022.

Radiologists Make More Errors Interpreting Off-Hours Body CT Studies during Overnight Assignments as Compared with Daytime Assignments.

Background There is increasing research attention on the impact of overnight work on radiologist performance. Prior studies on overnight imaging interpretive errors have focused on radiology residents, not on the relative performance of board-eligible or board-certified radiologists at night compared with during the day. Purpose To analyze the rate of clinically important interpretation errors on CT examinations of the abdomen, pelvis, or both ("body CT studies") committed by radiology fellows working off-hours based on day or night assignment. Materials and Methods Between July 2014 and June 2018, attending physicians at one tertiary care institution reviewed all body CT studies independently interpreted off-hours by radiologists in an academic fellowship within 10 hours of initial interpretation. Discrepancies affecting acute or follow-up clinical care were classified as errors. In this retrospective study, the error rate for studies interpreted during the day (between 7:00 am and 5:59 pm) was compared with that of studies interpreted at night (between 6:00 pm and 6:59 am). Error rate in the first half of day and night assignments was compared with error rate in the latter half. Statistical analyses used χ2 tests and general estimating equations; significance was defined as P < .05. Results There were 10 090 body CT studies interpreted by 32 radiologists. Forty-four of 2195 daytime studies (2.0%) had errors compared with 240 of 7895 nighttime studies (3.0%; P = .02). Twenty-two of 32 (69%) radiologists had higher error rates for night cases (P = .03). There were more errors in the last half of a night assignment (125 of 3358, 3.7%; P = .002) compared with the first half (115 of 4537, 2.5%). Conclusion On the basis of a subspecialty review, clinically important off-hours body CT interpretation errors occurred more frequently overnight and more frequently in the latter half of assignments, with more radiologists having worse error rates at night compared with the day. © RSNA, 2020 See also the editorial by Bruno in this issue.

Abdominal imaging findings in gastrointestinal basidiobolomycosis.

PURPOSE: To describe the abdominal imaging findings of patients with gastrointestinal Basidiobolus ranarum infection. METHODS: A literature search was performed to compile the abdominal imaging findings of all reported worldwide cases of gastrointestinal basidiobolomycosis (GIB). In addition, a retrospective review at our institution was performed to identify GIB cases that had imaging findings. A radiologist aware of the diagnosis reviewed the imaging findings in detail. Additional information was obtained from the medical records. RESULTS: A total of 73 GIB cases have been published in the medical literature. The most common abdominal imaging findings were masses in the colon, the liver, or multiple sites and bowel wall thickening. Initially, many patients were considered to have either a neoplasm or Crohn disease. We identified 7 proven cases of GIB at our institution, of which 4 had imaging studies (4 computed tomography [CT] examinations, 4 abdominal radiographs, and an upper gastrointestinal study). Imaging studies showed abnormalities in all 4 cases. Three-fourths of our study patients had an abdominal mass at CT. Two of 3 masses involved the kidneys and included urinary obstruction. All masses showed an inflammatory component with adjacent soft tissue stranding, with or without abscess formation. CONCLUSIONS: Radiologists should consider GIB when a patient from an arid climate presents with abdominal pain, weight loss, and an inflammatory abdominal mass on CT. Abdominal masses of the colon or liver, bowel wall thickening, and abscesses are the most common imaging findings.

Reducing the radiation dose for computed tomography colonography using model-based iterative reconstruction.

PURPOSE: To determine whether radiation doses during computed tomography (CT) colonography (CTC) can be further reduced while maintaining image quality using model-based iterative reconstruction (MBIR). METHODS: Twenty patients underwent CTC at a standard dose in supine and prone positions and at a reduced dose in the supine position. All other scan parameters (except noise index) were held constant. Acquisitions were reconstructed using 3 algorithms: filtered back projection (FBP), adaptive statistical iterative reconstruction (ASIR), and MBIR. Noise was assessed quantitatively by comparing the SD in Hounsfield units at 5 standard locations. Qualitative assessment was made by 2 experienced radiologists blinded to technique who subjectively scored image quality, noise, and sharpness (from 0 to 4). RESULTS: The standard-dose and reduced-dose CT dose index/dose-length product were 6.7/328 and 2.7 mGy/129 mGy-cm, respectively (60% reduction). Measured mean noise level increased from the standard to the reduced dose (FBP, from 58.6 to 97.2; ASIR from 35.8 to 60.6; and MBIR from 16.6 to 21.9). MBIR had significantly less noise than ASIR on 2-dimensional images at both standard and reduced doses (P < .01). CONCLUSIONS: Radiation dose in CTC using MBIR can be reduced by 60% while maintaining image quality and reducing image noise.

Diaphragm disease of the small bowel: a retrospective review of CT findings.

OBJECTIVE: The purpose of this article is to report the CT findings of pathologically proven diaphragm disease in the small bowel. MATERIALS AND METHODS: A retrospective review identified 12 patients with pathologically proven small-bowel diaphragm disease who underwent CT within 6 months of surgical resection. Two radiologists, who were unblinded to pathologic and clinical findings, evaluated CT examinations for imaging findings of disease extent, appearance, and location. Clinical history and postoperative follow-up were also performed. RESULTS: The most common presenting symptoms were abdominal pain (7/12 [58%]) and anemia (5/12 [42%]). Long-term use of nonsteroidal antiinflammatory drugs was documented in 58% (7/12) of patients. The most common location of small-bowel diaphragms was the ileum (8/12 [67%]). The CT findings were abnormal in 92% (11/12) of patients. The most common CT findings were small-bowel strictures (11/12 [92%]) and focal (median length, 1 cm) bowel wall thickening (8/12 [67%]). Other less common CT findings included mucosal hyperenhancement (6/12 [50%]), small-bowel dilatation (5/12 [42%]), and video capsule retention (6/9 [67%]). Postoperative follow-up in 11 patients found recurrent symptoms in four patients. CONCLUSION: Small-bowel diaphragm disease should be considered in patients with a history of long-term use of nonsteroidal antiinflammatory drugs, chronic abdominal pain, and anemia who present with CT findings of short, symmetric ileal strictures and focal bowel wall thickening.

CT colonography for the detection of nonpolypoid adenomas: sensitivity assessed with restricted national CT colonography trial criteria.

OBJECTIVE: The purpose of this study was to determine the prevalence of nonpolypoid adenomas and the sensitivity of CT colonography (CTC) in their detection by use of the restricted criteria of height-to-width ratio<50% and height elevation≤3 mm. MATERIALS AND METHODS: In the National CT Colonography Trial (American College of Radiology Imaging Network protocol 6664), a cohort of 2531 participants without symptoms underwent CTC and screening colonoscopy. The CTC examinations were interpreted with both 2D and 3D techniques. Nonpolypoid adenomatous polyps identified with CTC or colonoscopy were retrospectively reviewed to determine which polyps met the restricted criteria. The prevalence of nonpolypoid adenomas and the prospective sensitivity of CTC were determined. Descriptive statistics were used to report the prevalence, size, and histologic features. The sensitivities (with 95% CIs) for nonpolypoid and polypoid lesions were compared by two-sided Z test for independent binomial proportions. RESULTS: The retrospective review confirmed 21 nonpolypoid adenomas, yielding a prevalence of 0.83% (21 of 2531 participants). Eight (38.1%) were advanced adenomas, many (50% [4/8]) only because of large size (≥10 mm). The overall per polyp sensitivity of CTC (combined 2D and 3D interpretation) for detecting nonpolypoid adenomas≥5 mm (n=21) was 0.76; ≥6 mm (n=16), 0.75; and ≥10 mm (n=5), 0.80. These values were not statistically different from the sensitivity of detecting polypoid adenomas (p>0.37). CONCLUSION: In this large screening population, nonpolypoid adenomas had a very low prevalence (<1%), and advanced pathologic features were uncommon in polyps<10 mm in diameter. Most nonpolypoid adenomas are technically visible at CTC. The prospective sensitivity is similar to that for polypoid adenomas when the interpretation combines both 2D and 3D review.

Noncathartic CT colonography: Image quality assessment and performance and in a screening cohort.

OBJECTIVE: Cathartic bowel preparation is a major barrier for colorectal cancer screening. We examined noncathartic CT colonography (CTC) quality and performance using four similar bowel-tagging regimens in an asymptomatic screening cohort. SUBJECTS AND METHODS: This prospective study included 564 asymptomatic subjects who underwent noncathartic CTC without dietary modification but with 21 g of barium with or without iodinated oral contrast material (four regimens). The quality of tagging with oral agents was evaluated. A gastrointestinal radiologist evaluated examinations using primary 2D search supplemented by electronic cleansing (EC) and 3D problem solving. Results were compared with complete colonoscopy findings after bowel purgation and with retrospective unblinded evaluation in 556 of the 564 (99%) subjects. RESULTS: Of the 556 subjects, 7% (37/556) and 3% (16/556) of patients had 52 and 20 adenomatous polyps ≥ 6 and ≥ 10 mm, respectively. The addition of iodine significantly improved the percentage of labeled stool (p ≤ 0.0002) and specificity (80% vs 89-93%, respectively; p = 0.046). The overall sensitivity of noncathartic CTC for adenomatous polyps ≥ 6 mm was 76% (28/37; 95% CI, 59-88%), which is similar to the sensitivity of the iodinated regimens with most patients (sensitivity: 231 patients, 74% [14/19; 95% CI, 49-91%]; 229 patients, 80% [12/15; 95% CI, 52-96%]). The negative predictive value was 98% (481/490), and the lone cancer was detected (0.2%, 1/556). EC was thought to improve conspicuity of 10 of 21 visible polyps ≥ 10 mm. CONCLUSION: In this prospective study of asymptomatic subjects, the per-patient sensitivity of noncathartic CTC for detecting adenomas ≥ 6 mm was approximately 76%. Inclusion of oral iodine contrast material improves examination specificity and the percentage of labeled stool. EC may improve polyp conspicuity.

Strategies for improving colorectal cancer detection with routine computed tomography.

PURPOSE: To report the detection rate of colorectal tumors with computed tomography (CT) performed within 1 year before diagnosis for indications other than colon abnormalities. Strategies to improve cancer detection are reported. METHODS: Two board-certified, subspecialty-trained abdominal radiologists retrospectively reviewed patient health records and CT images with knowledge of tumor location/size. Patients were classified into 3 groups: prospective (colon abnormality suggesting neoplasm documented in radiologic report), retrospective (not documented in radiologic report but detected in our retrospective review of CT images), and undetected (neither prospectively nor retrospectively detected). Retrospective detection confidence and morphologic characteristics of each tumor were also recorded. RESULTS: Of 209 included patients, 106 (50.7%) had prospectively detected tumors, 66 (31.6%) had retrospectively detected tumors, and 37 (17.7%) had undetected tumors. Asymmetric bowel wall thickening and polypoid masses were present more often in the retrospective group than in the prospective group (27% vs. 10.5% and 26% vs. 17.1%, respectively). Tumors in the ascending colon were more likely to be detected retrospectively than prospectively (odds ratio, 2.75; 95% CI 1.07-7.08; P = 0.04). Undetected tumors were smaller on average (2.9 cm) than prospective (6.0 cm) and retrospective (4.9 cm) tumors (P = 0.03). Detection confidence was lower for retrospectively detected tumors than for prospectively detected tumors (P = 0.03). Indications other than abdominal pain were most common for retrospectively detected tumors (P = 0.03). Use of intravenous contrast material was lowest in the undetected group (P = 0.003). The prospective group had more pericolonic abnormalities, regional/retroperitoneal lymph node involvement (P < 0.001), and distant metastases than did the retrospective group (P = 0.01). CONCLUSION: Half of all colorectal tumors were not detected prospectively. Radiologists should perform meticulous colon tracking regardless of the indication for CT. The right colon merits additional examination. Polypoid and asymmetric morphologic characteristics were most often overlooked, but these characteristics can be learned to improve detection.

The National CT Colonography Trial: assessment of accuracy in participants 65 years of age and older.

PURPOSE: To conduct post-hoc analysis of National CT Colonography Trial data and compare the sensitivity and specificity of computed tomographic (CT) colonography in participants younger than 65 years with those in participants aged 65 years and older. MATERIALS AND METHODS: Of 2600 asymptomatic participants recruited at 15 centers for the trial, 497 were 65 years of age or older. Approval of this HIPAA-compliant study was obtained from the institutional review board of each site, and informed consent was obtained from each subject. Radiologists certified in CT colonography reported lesions 5 mm in diameter or larger. Screening detection of large (≥10-mm) histologically confirmed colorectal neoplasia was the primary end point; screening detection of smaller (6-9-mm) colorectal neoplasia was a secondary end point. The differences in sensitivity and specificity of CT colonography in the two age cohorts (age < 65 years and age ≥ 65 years) were estimated with bootstrap confidence intervals (CIs). RESULTS: Complete data were available for 477 participants 65 years of age or older (among 2531 evaluable participants). Prevalence of adenomas 1 cm or larger for the older participants versus the younger participants was 6.9% (33 of 477) versus 3.7% (76 of 2054) (P < .004). For large neoplasms, mean estimates for CT colonography sensitivity and specificity among the older cohort were 0.82 (95% CI: 0.644, 0.944) and 0.83 (95% CI: 0.779, 0.883), respectively. For large neoplasms in the younger group, CT colonography sensitivity and specificity were 0.92 (95% CI: 0.837, 0.967) and 0.86 (95% CI: 0.816, 0.899), respectively. Per-polyp sensitivity for large neoplasms for the older and younger populations was 0.75 (95% CI: 0.578, 0.869) and 0.84 (95% CI: 0.717, 0.924), respectively. For the older and younger groups, per-participant sensitivity was 0.72 (95% CI: 0.565, 0.854) and 0.81 (95% CI: 0.745, 0.882) for detecting adenomas 6 mm in diameter or larger. CONCLUSION: For most measures of diagnostic performance and in most subsets, the difference between senior-aged participants and those younger than 65 years was not statistically significant.

Designing a safer radiology department.

OBJECTIVE: Patients presume safety in radiologic services, but the potential to do harm exists in every area of imaging. Radiology department personnel need to understand basic regulatory requirements for safety and how to promote and improve safety in the future. CONCLUSION: This article reviews key safety metrics that we think are relevant to radiology and discusses how to define the measures and how we are attempting to translate the metrics into a culture of safety.

Accuracy of CT colonography for detection of large adenomas and cancers.

BACKGROUND: Computed tomographic (CT) colonography is a noninvasive option in screening for colorectal cancer. However, its accuracy as a screening tool in asymptomatic adults has not been well defined. METHODS: We recruited 2600 asymptomatic study participants, 50 years of age or older, at 15 study centers. CT colonographic images were acquired with the use of standard bowel preparation, stool and fluid tagging, mechanical insufflation, and multidetector-row CT scanners (with 16 or more rows). Radiologists trained in CT colonography reported all lesions measuring 5 mm or more in diameter. Optical colonoscopy and histologic review were performed according to established clinical protocols at each center and served as the reference standard. The primary end point was detection by CT colonography of histologically confirmed large adenomas and adenocarcinomas (10 mm in diameter or larger) that had been detected by colonoscopy; detection of smaller colorectal lesions (6 to 9 mm in diameter) was also evaluated. RESULTS: Complete data were available for 2531 participants (97%). For large adenomas and cancers, the mean (+/-SE) per-patient estimates of the sensitivity, specificity, positive and negative predictive values, and area under the receiver-operating-characteristic curve for CT colonography were 0.90+/-0.03, 0.86+/-0.02, 0.23+/-0.02, 0.99+/-<0.01, and 0.89+/-0.02, respectively. The sensitivity of 0.90 (i.e., 90%) indicates that CT colonography failed to detect a lesion measuring 10 mm or more in diameter in 10% of patients. The per-polyp sensitivity for large adenomas or cancers was 0.84+/-0.04. The per-patient sensitivity for detecting adenomas that were 6 mm or more in diameter was 0.78. CONCLUSIONS: In this study of asymptomatic adults, CT colonographic screening identified 90% of subjects with adenomas or cancers measuring 10 mm or more in diameter. These findings augment published data on the role of CT colonography in screening patients with an average risk of colorectal cancer. (ClinicalTrials.gov number, NCT00084929; American College of Radiology Imaging Network [ACRIN] number, 6664.)

Comparative economic evaluation of data from the ACRIN National CT Colonography Trial with three cancer intervention and surveillance modeling network microsimulations.

PURPOSE: To estimate the cost-effectiveness of computed tomographic (CT) colonography for colorectal cancer (CRC) screening in average-risk asymptomatic subjects in the United States aged 50 years. MATERIALS AND METHODS: Enrollees in the American College of Radiology Imaging Network National CT Colonography Trial provided informed consent, and approval was obtained from the institutional review board at each site. CT colonography performance estimates from the trial were incorporated into three Cancer Intervention and Surveillance Modeling Network CRC microsimulations. Simulated survival and lifetime costs for screening 50-year-old subjects in the United States with CT colonography every 5 or 10 years were compared with those for guideline-concordant screening with colonoscopy, flexible sigmoidoscopy plus either sensitive unrehydrated fecal occult blood testing (FOBT) or fecal immunochemical testing (FIT), and no screening. Perfect and reduced screening adherence scenarios were considered. Incremental cost-effectiveness and net health benefits were estimated from the U.S. health care sector perspective, assuming a 3% discount rate. RESULTS: CT colonography at 5- and 10-year screening intervals was more costly and less effective than FOBT plus flexible sigmoidoscopy in all three models in both 100% and 50% adherence scenarios. Colonoscopy also was more costly and less effective than FOBT plus flexible sigmoidoscopy, except in the CRC-SPIN model assuming 100% adherence (incremental cost-effectiveness ratio: $26,300 per life-year gained). CT colonography at 5- and 10-year screening intervals and colonoscopy were net beneficial compared with no screening in all model scenarios. The 5-year screening interval was net beneficial over the 10-year interval except in the MISCAN model when assuming 100% adherence and willingness to pay $50,000 per life-year gained. CONCLUSION: All three models predict CT colonography to be more costly and less effective than non-CT colonographic screening but net beneficial compared with no screening given model assumptions.

ACRIN CT colonography trial: does reader's preference for primary two-dimensional versus primary three-dimensional interpretation affect performance?

PURPOSE: To determine whether the reader's preference for a primary two-dimensional (2D) or three-dimensional (3D) computed tomographic (CT) colonographic interpretation method affects performance when using each technique. MATERIALS AND METHODS: In this institutional review board-approved, HIPAA-compliant study, images from 2531 CT colonographic examinations were interpreted by 15 trained radiologists by using colonoscopy as a reference standard. Through a survey at study start, study end, and 6-month intervals, readers were asked whether their interpretive preference in clinical practice was to perform a primary 2D, primary 3D, or both 2D and 3D interpretation. Readers were randomly assigned a primary interpretation method (2D or 3D) for each CT colonographic examination. Sensitivity and specificity of each method (primary 2D or 3D), for detecting polyps of 10 mm or larger and 6 mm or larger, based on interpretive preference were estimated by using resampling methods. RESULTS: Little change was observed in readers' preferences when comparing them at study start and study end, respectively, as follows: primary 2D (eight and seven readers), primary 3D (one and two readers), and both 2D and 3D (six and six readers). Sensitivity and specificity, respectively, for identifying examinations with polyps of 10 mm or larger for readers with a primary 2D preference (n = 1128 examinations) were 0.84 and 0.86, which was not significantly different from 0.84 and 0.83 for readers who preferred 2D and 3D (n = 1025 examinations) or from 0.76 and 0.82 for readers with a primary 3D preference (n = 378 examinations). When performance by using the assigned 2D or 3D method was evaluated on the basis of 2D or 3D preference, there was no difference among those readers by using their preferred versus not preferred method of interpretation. Similarly, no significant difference among readers or preferences was seen when performance was evaluated for detection of polyps of 6 mm or larger. CONCLUSION: The reader's preference for interpretive method had no effect on CT colonographic performance.

National CT colonography trial (ACRIN 6664): comparison of three full-laxative bowel preparations in more than 2500 average-risk patients.

OBJECTIVE: The purpose of our study was to compare the effect of three different full-laxative bowel preparations on patient compliance, residual stool and fluid, reader confidence, and polyp detection at CT colonography (CTC). SUBJECTS AND METHODS: A total of 2531 patients underwent CTC followed by colonoscopy for the American College of Radiology Imaging Network (ACRIN) National CTC Trial. Of this total, 2525 patients used one of three bowel preparations with bisacodyl tablets and stool and fluid tagging: 4 L of polyethylene glycol (PEG); 90 mL of phosphosoda; or 300 mL of magnesium citrate. Patients reported percent compliance with the bowel preparation and radiologists graded each CTC examination for the amount of residual fluid and stool on a scale from 1 (none) to 4 (nondiagnostic). Reader confidence for true-positive findings was reported on a 5-point scale: 1 (low) to 5 (high). Sensitivity and specificity for detecting polyps ≥ 6 mm and ≥ 1 cm compared with colonoscopy were calculated for each preparation. RESULTS: The most commonly prescribed preparation was phosphosoda (n = 1403) followed by PEG (n = 1020) and magnesium citrate (n = 102). Phosphosoda had the highest patient compliance (p = 0.01), least residual stool (p < 0.001), and highest reader confidence versus PEG for examinations with polyps (p = 0.06). Magnesium citrate had significantly more residual fluid compared with PEG and phosphosoda (p = 0.006). The sensitivity and specificity for detecting colon polyps ≥ 6 mm and ≥ 1 cm did not differ significantly between preparations. CONCLUSION: Polyp detection was comparable for all three preparations, although phosphosoda had significantly higher patient compliance and the least residual stool.

Partial preparation computed tomographic colonography: a feasibility study.

We retrospectively evaluated computed tomographic colonography examinations of patients who have had a partial bowel preparation and compared the quality of their preparation with patients who have had a full bowel preparation. In total, 27 patients undergoing computed tomographic colonography examination (10 patients with partial bowel preparation and 17 with full bowel preparation) had their examinations retrospectively reviewed by three independent radiologists in a blinded manner, with evaluation of residual stool, distention, residual fluid, and overall bowel preparation quality. Six colon segments were evaluated individually and independently for these four variables (a total of 161 segments tested). Comparisons were made with the Mann-Whitney test between the partial preparation group and the full preparation group. Partial preparation included stool and fluid tagging plus 20 mg of bisacodyl orally; full preparation included stool and fluid tagging plus 2 L of polyethylene glycol solution. No significant clinical difference was found in colon preparation between the partial and full bowel preparation groups--when evaluated with individual colon segments or by independent readers. Interreader correlation was high. This pilot study indicates that full bowel preparation is not required for diagnostic-quality computed tomographic colonography examination. Further evaluation of this partial bowel preparation regimen is warranted.

Reducing the radiation dose for CT colonography using adaptive statistical iterative reconstruction: A pilot study.

OBJECTIVE: The purpose of our study was to evaluate the feasibility of preserving image quality during CT colonography (CTC) using a reduced radiation dose with adaptive statistical iterative reconstruction (ASIR). MATERIALS AND METHODS: A proven colon phantom was imaged at standard dose settings (50 mAs) and at reduced doses (10-40 mAs) using six different ASIR levels (0-100%). We assessed 2D and 3D image quality and noise to determine the optimal dose and ASIR setting. Eighteen patients were then scanned with a standard CTC dose (50 mAs) in the supine position and at a reduced dose of 25 mAs with 40% ASIR in the prone position. Three radiologists blinded to the scanning techniques assessed 2D and 3D image quality and noise at three different colon locations. A score difference of > or = 1 was considered clinically important. Actual noise measures were compared between the standard-dose and low-dose acquisitions. RESULTS: The phantom study showed image noise reduction that correlated with a higher percentage of ASIR. In patients, no significant image quality differences were identified between standard- and low-dose images using 40% ASIR. Overall image quality was reduced for both image sets as body mass index increased. Measured image noise was less with the low-dose technique using ASIR. CONCLUSION: The results of this pilot study show that the radiation dose during CTC can be reduced 50% below currently accepted low-dose techniques without significantly affecting image quality when ASIR is used. Further evaluation in a larger patient group is warranted.

Process improvement: what is it, why is it important, and how is it done?

OBJECTIVE: The purpose of this study was to provide enough information so beginners can feel comfortable starting and completing a simple radiology process improvement project. CONCLUSION: Medical practices (including radiology departments) need to address outstanding quality and safety issues that threaten their patients. Addressing these issues improves patient care and operational efficiency. We provide a review of our approach to process improvement and the established improvement methods. Many organizations and companies are available to support medical practices as they enter this field.