Volumetric growth rates of sessile serrated adenomas/polyps observed in situ at longitudinal CT colonography.

OBJECTIVE: Sessile serrated adenomas/polyps (SSA/Ps) are now recognized as potential cancer precursors, but little is known about their natural history. We assessed the in vivo growth rates of histologically proven SSA/Ps at longitudinal CT colonography (CTC) and compared results with non-advanced tubular adenomas (TAs). METHODS: We identified a cohort of 53 patients (mean age, 54.8 ± 5.5 years; M:F, 26:27) from one center with a total of 58 SSA/Ps followed longitudinally at CTC (mean follow-up interval, 5.3 ± 1.9 years). Initial and final size measurements were determined using dedicated CTC software. Findings were compared with 141 non-advanced TAs followed at CTC (mean, 4.1 ± 2.3 years) in 113 patients (mean age, 56.8 ± 6.9 years). RESULTS: SSA/Ps were more often flat (62% [36/58] vs. 14% [20/141], p < 0.0001) and right-sided (98% [57/58] vs. 46% [65/141], p < 0.0001) compared with TAs. Initial average diameter was greater for SSA/Ps (9.3 mm vs. 6.3 mm; p < 0.0001). Mean annual volumetric growth was + 12.7%/year for SSA/Ps vs. + 36.4%/year for TAs (p = 0.028). Using a previously defined threshold of + 20% increase in volume/year to define progression, 22% (13/58) of SSA/Ps and 41% (58/141) of TAs progressed (p = 0.014). None of the SSA/Ps had dysplasia or invasive cancer at histopathology. CONCLUSIONS: Sessile serrated adenoma/polyps demonstrate slower growth compared with conventional non-advanced tubular adenomas, despite larger initial linear size. This less aggressive behavior may help explain the more advanced patient age for serrated pathway cancers. Furthermore, these findings could help inform future colonoscopic surveillance strategies, as current guidelines are largely restricted to expert opinion related to the absence of natural history data. KEY POINTS: • Sessile serrated adenoma/polyps (SSA/Ps) tend to be flat, right-sided, and demonstrate slower growth compared with conventional non-advanced tubular adenomas. • This less aggressive behavior of SSA/Ps may help explain the more advanced patient age for serrated pathway cancers.

Effect of IV contrast on lumbar trabecular attenuation at routine abdominal CT: correlation with DXA and implications for opportunistic osteoporosis screening.

UNLABELLED: Osteoporosis remains under-diagnosed. Routine abdominal CT can provide opportunistic screening, but the effect of IV contrast is largely unknown. The overall performance for predicting osteoporosis was similar between enhanced and unenhanced scans. Therefore, both non-contrast and contrast-enhanced abdominal CT scans can be employed for opportunistic osteoporosis screening. INTRODUCTION: Osteoporosis is an important yet under-diagnosed public health concern. Lumbar attenuation measurement at routine abdominal CT can provide a simple opportunistic initial screen, but the effect of IV contrast has not been fully evaluated. METHODS: Mean trabecular CT attenuation values (in Hounsfield units, HU) at the L1 vertebral level were measured by oval region-of-interest (ROI) on both the unenhanced and IV-contrast-enhanced CT series in 157 adults (mean age, 62.0). All patients underwent correlative central DXA within 6 months of CT. Based on DXA BMD of the lumbar spine, femoral neck, and total proximal femur: osteoporosis, osteopenia, and normal BMD was present in 33, 77, and 47, respectively. Statistical analysis included Bland-Altman plots and receiver operating characteristic (ROC) curves. RESULTS: Mean difference (±SD) in L1 trabecular attenuation between enhanced and unenhanced CT series was +11.2 HU (±19.2) (95 % CI, 8.16-14.22 HU), an 8 % difference. Intra-patient variation was substantial, but no overall trend in the HU difference was seen according to underlying BMD. ROC area under the curve (AUC) for unenhanced and enhanced CT for diagnosing osteoporosis were similar at 0.818 and 0.830, respectively (p = 0.632). Thresholds for maintaining 90 % specificity for osteoporosis were 90 HU for unenhanced and 102 HU for enhanced CT. Thresholds for maintaining 90 % sensitivity for osteoporosis were 139 HU for unenhanced and 144 HU for enhanced CT. Similar diagnostic performance was seen for diagnosing low BMD (osteoporosis or osteopenia) using higher HU cut-offs. CONCLUSION: Contrast-enhanced CT shows an average increase of 11 HU over the unenhanced series for L1 trabecular attenuation. The overall performance for predicting osteoporosis is similar between the enhanced and unenhanced scans, thus either can be employed for initial opportunistic screening.

Opportunistic screening for osteoporosis using the sagittal reconstruction from routine abdominal CT for combined assessment of vertebral fractures and density.

SUMMARY: Opportunistic osteoporosis screening using abdominal CT scans obtained for other purposes has the potential to increase detection of those at increased risk for fragility fractures. We sought to combine the tasks of density measurement and vertebral fracture assessment on the sagittal view. We confirm that this represents a robust approach and recommend its implementation in clinical practice. INTRODUCTION: Opportunistic osteoporosis screening at routine abdominal CT has been proposed by measuring axial (transverse) L1 trabecular attenuation and by sagittal reconstruction for vertebral fracture assessment. We sought to combine this dual evaluation on the sagittal reconstruction alone to improve efficiency. METHODS: Routine contrast-enhanced abdominal CT scans performed for any indication on 571 consecutive adults age 60 years or older (mean age 70.7 years) were retrospectively analyzed. These were performed at a single center over a 3-month period. L1 trabecular attenuation was measured using an ovoid region-of-interest on both the transverse and sagittal series. The sagittal reconstruction was also analyzed for moderate-to-severe vertebral compression fractures using the Genant visual semi-quantitative method. Likely osteoporosis was defined by a moderate-to-severe fracture and/or sagittal L1 trabecular attenuation of ≤110 Hounsfield units (HU) (previously found to be >90% specific for osteoporosis on our calibrated GE CT scanners at 120 kV(p)). Correlation was made with hip and spine dual X-ray absorptiometry (DXA). RESULTS: Mean absolute difference in L1 trabecular attenuation between transverse and sagittal reconstructions was 6.7 HU (±5.7) or 6.2%. The transverse and sagittal HU measurements were in agreement (i.e., both measurements above or below this threshold) in 94.5% of cases at the 110-HU cutoff. A total of 243 (42.3%) patients had likely osteoporosis by CT criteria, of which only 48 (19.8%) had previous DXA screening. CONCLUSION: Assessment of the sagittal view alone at routine abdominal CT for both vertebral fractures and trabecular bone mineral density provides a rapid and effective opportunistic screen for detecting individuals at increased risk for fragility fractures.

Extramedullary haematopoiesis: radiological imaging features.

Extramedullary haematopoiesis (EMH) is defined as the production of blood cells outside of the bone marrow, which occurs when there is inadequate production of blood cells. The most common causes of EMH are myelofibrosis, diffuse osseous metastatic disease replacing the bone marrow, leukaemia, sickle cell disease, and thalassemia. The purpose of this article is to review the common and uncommon imaging appearances of EMH by anatomical compartment. In the thorax, EMH most commonly presents as paravertebral fat-containing masses, and typically does not present a diagnostic dilemma; however, EMH in the abdomen most commonly manifests as hepatosplenomegaly with or without focal soft-tissue masses in the liver, spleen, perirenal space, and in the peritoneum. Hepatosplenomegaly, a non-specific feature, most often occurs without an associated focal mass, which makes suggestion of EMH difficult. EMH manifesting as visceral soft-tissue masses often requires biopsy as the differential diagnosis can include lymphoma, metastatic disease, and sarcoma. Many of these soft-tissue masses do not contain adipose elements, making the diagnosis of EMH difficult. Clinical history is crucial, as EMH would likely not otherwise be in the differential in patients with non-specific abdominal masses. Careful biopsy planning is necessary when EMH is a diagnostic consideration, given the propensity for haemorrhage. Understanding the typical imaging appearances of EMH based on its site of manifestation can help the radiologist when encountered with a finding that is diagnostic for EMH, and can help the radiologist suggest the need and plan appropriately for image-guided biopsy.

MDCT diagnosis of gastroduodenal ulcers: key imaging features with endoscopic correlation.

Although the overall prevalence of peptic ulcer disease (PUD) and related hospitalizations are decreasing, the initial presentation of complicated PUD on CT remains common. It, therefore, remains critical for radiologists to recognize the findings of PUD at CT for initial diagnosis. While the CT findings of complicated PUD have been previously described in the literature, the CT findings of uncomplicated PUD have not been well documented. Furthermore, although CT is certainly not the diagnostic evaluation of choice for patients with suspected uncomplicated PUD, many patients with PUD will nonetheless present to the emergency department with unexplained abdominal pain and undergo MDCT evaluation as the initial diagnostic test. Therefore, recognizing the MDCT findings of uncomplicated PUD can help appropriately direct patient management, and help prevent the development of complications. To facilitate improved recognition of PUD on abdominal CT, we present an overview of the CT findings of both uncomplicated and complicated PUD, as well as several diagnostic pitfalls which can result in misdiagnosis from peptic ulcer mimics.

Intra-individual comparison of magnesium citrate and sodium phosphate for bowel preparation at CT colonography: automated volumetric analysis of residual fluid for quality assessment.

AIM: To perform an objective, intra-individual comparison of residual colonic fluid volume and attenuation associated with the current front-line laxative magnesium citrate (MgC) versus the former front-line laxative sodium phosphate (NaP) at CT colonography (CTC). MATERIALS AND METHODS: This retrospective Health Insurance and Portability and Accountability Act-compliant study had institutional review board approval; informed consent was waived. The study cohort included 250 asymptomatic adults (mean age at index 56.1 years; 124 male/126 female) who underwent CTC screening twice over a 5 year interval. Colon catharsis at initial and follow-up screening employed single-dose NaP and double-dose MgC, respectively, allowing for intra-patient comparison. Automated volumetric analysis of residual colonic fluid volume and attenuation was performed on all 500 CTC studies. Colonic fluid volume <200 ml and mean attenuation between 300-900 HU were considered optimal. Paired t-test and McNemar's test were used to compare differences. RESULTS: Residual fluid volumes <200 ml were recorded in 192 examinations (76.8%) following MgC and in 204 examinations (81.6%) following NaP (p = 0.23). The mean total residual fluid volume was 155 ± 114 ml for MgC and 143 ± 100 ml for NaP (p = 0.01). The attenuation range of 300-900 HU was significantly more frequent for MgC (n = 220, 88%) than for NaP (n = 127, 50.8%; p < 0.001). Mean fluid attenuation was significantly lower for MgC (700 ± 165 HU) than for NaP (878 ± 155 HU; p < 0.001). Concomitant presence of both optimal fluid volume and attenuation was significantly more frequent for MgC 65.2% than for NaP (38%; p < 0.001). CONCLUSIONS: Objective intra-individual comparison using automated volumetric analysis suggests that the replacement of NaP by MgC as the front-line laxative for CTC has not compromised overall examination quality.

Spectrum of imaging findings in hyperplastic cholecystosis and potential mimics.

Adenomyomatosis and cholesterolosis of the gallbladder, collectively termed hyperplastic cholecystosis, are commonly encountered incidental findings on imaging studies performed for a variety of indications including biliary colic or nonspecific abdominal pain. These pathologies are rarely the source of symptoms, generally considered benign and do not require further work-up. However, their imaging characteristics can overlap with more sinister conditions that should not be missed. In this review, the imaging findings of adenomyomatosis and cholesterolosis will be reviewed followed by other gallbladder pathologies that might mimic these conditions radiologically. Important differentiating factors will be discussed that can aid the radiologist in making a more confident imaging diagnosis.

Evaluation of patient tissue selection methods for deriving equivalent density calibration for femoral bone quantitative CT analyses.

Osteoporosis affects an increasing number of people every year and patient specific finite element analysis of the femur has been proposed to identify patients that could benefit from preventative treatment. The aim of this study was to demonstrate, verify, and validate an objective process for selecting tissues for use as the basis of phantomless calibration to enable patient specific finite element analysis derived hip fracture risk prediction. Retrospective reanalysis of patient computed tomography (CT) scans has the potential to yield insights into more accurate prediction of osteoporotic fracture. Bone mineral density (BMD) specific calibration scans are not typically captured during routine clinical practice. Tissue-based BMD calibration can therefore empower the retrospective study of patient CT scans captured during routine clinical practice. Together the method for selecting tissues as the basis for phantomless calibration coupled with the post-processing steps for deriving a calibration equation using the selected tissues provide an estimation of quantitative equivalent density results derived using calibration phantoms. Patient tissues from a retrospective cohort of 211 patients were evaluated. The best phantomless calibration resulted in a femoral strength (FS) [N] bias of 0.069 ± 0.07% over FS derived from inline calibration and a BMD [kg/cm3] bias of 0.038 ± 0.037% over BMD derived from inline calibration. The phantomless calibration slope for the best method presented was within the range of patient specific calibration curves available for comparison and demonstrated a small bias of 0.028 ± 0.054 HU/(mg/cm3), assuming the Mindways Model 3 BMD inline calibration phantom as the gold standard. The presented method of estimating a calibration equation from tissues showed promise for CT-based femoral fracture analyses of retrospective cohorts without readily available calibration data.

Impact of lifestyle factors on colorectal polyp detection in the screening setting.

BACKGROUND: Awareness of risk factors for colorectal neoplasia could address risk reduction strategies in asymptomatic subjects. METHODS: This is a post hoc analysis of a prospective, cross-sectional study of 1321 asymptomatic adults. All the subjects underwent same-day CT colonography and colonoscopy to determine the prevalence of colorectal neoplasia. The variables examined included body mass index, smoking, alcohol consumption, age, and gender. Univariate and logistic regression analyses were performed for detection of colorectal neoplasia and hyperplastic polyps. Odds ratios with 95% confidence intervals were calculated. RESULTS: Colorectal adenomas and hyperplastic polyps were detected in 378 (28.6%) and 157 (11.9%) participants, respectively. In both univariate and multivariate analysis, increasing age, male gender, and body mass index > or =25 were significantly associated with the detection of colorectal adenomas, with an odds ratio of 1.22 (95% CI,1.09-1.36), 1.28 (95% CI, 1.06-1.45), and 1.34 (95% CI, 1.02-1.77), respectively. A history of smoking was the only identifiable risk factor for hyperplastic polyps (odds ratio, 1.98; 95% CI, 1.41-2.78). CONCLUSIONS: Body mass index > or =25, increasing age, and male gender were all associated with an increased likelihood of colorectal adenomas at screening, whereas smoking was strongly associated with hyperplastic polyps.

Colorectal anatomy in adults at computed tomography colonography: normal distribution and the effect of age, sex, and body mass index.

BACKGROUND AND STUDY AIMS: Computed tomography colonography (CTC) is an accurate tool for assessing the large intestinal anatomy. Our aims were to determine the normal distribution of in vivo colorectal anatomy and to investigate the effect of age, sex, and body mass index (BMI) on colorectal length. PATIENTS AND METHODS: Asymptomatic adults who underwent primary CTC examination at a single institution over an 8-month period were evaluated. The interactive three-dimensional map was used to determine total and segmental lengths and number of acute-angle flexures. The two-dimensional multiplanar display was used to measure luminal diameters. The effects of age, sex, and BMI on colorectal lengths were examined. RESULTS: The study cohort consisted of 505 consecutive adults (266 women, mean age 56.6 years). Mean total colorectal length was 189.5 +/- 26.3 cm and mean number of acute-angle flexures was 10.9 +/- 2.4. Total length for older adults (> 60 years) did not significantly differ from those who were younger than 60 years ( P = 0.22), although the transverse colon was significantly longer in older adults ( P = 0.04). Women had significantly longer colons than men (193.3 cm vs. 185.4 cm, P = 0.002), whereas overweight adults (BMI > 25) had significantly shorter colons compared with those with BMI

Effect of visualization display colour on polyp conspicuity at virtual colonoscopy.

AIM: To investigate the effect of different colour three-dimensional (3D) displays on polyp detection at virtual colonoscopy (VC). METHODS: Five VC trained observers were shown "brief flashes" (lasting 0.2s) of 125 3D endoluminal image snap-shots, repeated for each of six display colours (750 images total). One hundred images contained a single polyp (diameter range 5-42 mm) and 25 contained no polyp ("normal"). Images were reviewed in random order over five reading sessions, readers recording either normality or presence and location of a polyp. Multilevel logistic regression was used to examine any influence of colour on polyp detection stratified according to polyp size (medium 5-9 mm/large >or=10mm). The kappa statistic was used to assess effect of colour on observer agreement. RESULTS: Individual reader polyp detection rates ranged between 75-94%. Compared to the default pink "soft tissue" display, the odds of polyp detection were 0.65 (CI 0.41,1.01) for green, 0.82 (0.53,1.30) for blue, 1 (0.63,1.59) for red, 1.12 (0.7,1.79) for monochrome, and 1.15 for yellow (0.72,1.84). Overall, there was no significant difference between the displays (p=0.11). Including normal cases, there was no overall difference in correct case classification between the six colours (p=0.44). The odds of detecting large versus medium polyps was significantly greater for 3/5 observers; odds ratio (OR) 2.84-10.1, although unaffected by display colour (p=0.3). CONCLUSION: The background colour display generally has a minimal effect on polyp detection at VC, although green should be avoided.

Computed tomographic colonography for colorectal screening.

Computed tomographic colonography (CTC) is a specialized computed tomographic examination that has been optimized for the detection of colorectal polyps. The technology has undergone major advances in recent years and there is emerging consensus that state-of-the-art CTC results in performance characteristics comparable to those of optical colonoscopy for polyps > or = 8 mm in size. Effective polyp detection rests on the quality of several components of the examination, which must all be optimized in order to maintain appropriate sensitivity and specificity, including adequate bowel preparation, good colonic distension, sufficient scanning parameters, and appropriate interpretation. The emergence of CTC provides another method of colonic evaluation for colorectal cancer screening and prevention. In contrast to a mutually exclusive approach to screening, the availability of both optical colonoscopy and CTC should hopefully improve overall compliance rates for colorectal screening. The ultimate role of this technique in the screening program continues to evolve. There is currently considerable variability in the materials and methods used in CTC. This article describes the approach used at the University of Wisconsin, which has been validated in a large multicenter screening trial and which is currently used for an active CTC-based colorectal cancer screening program.

Detection of potentially relevant extracolonic and colorectal findings at CT colonography in a low-risk symptomatic patient population.

PURPOSE: CT colonography (CTC) is a widely accepted examination tool for detection of colorectal lesions but evidence of the proportions of relevant extracolonic findings (ECF) in a large symptomatic but still relatively low-risk cohort is lacking, as well as their relationship to symptoms, age, and sex. METHODS: All patients (n = 3208) with colorectal symptoms, imaged between January 2007 and September 2016 with first-time CTC, were retrospectively selected. The majority (96.7%) was examined with low-dose unenhanced protocol. The most relevant ECF and colorectal lesions (≥6 mm) were prospectively assessed according to C-RADS classifications. Follow-up was elaborated based on the electronic record review. Chi-square test was utilized for evaluating the associations between relevant findings and symptoms, age, and sex. RESULTS: A total of 270 (8.4%) patients were classified as C-RADS E3, 63 (2.0%) patients as C-RADS E4, and 437 (13.6%) patients were assessed with colorectal lesions (C-RADS C2-4). At follow-up, two thirds of ECF turned out to be a malignancy or relevant disease that required further medical attention. The proportion of ECF was not related to specific colorectal symptoms. Patients aged ≥65 years and men had significantly higher proportions of ECF than younger patients (C-RADS E3 p = 0.005; C-RADS E4 p < 0.001) and women (C-RADS E3 p = 0.013; C-RADS E4 p = 0.009), respectively. CONCLUSION: Proportions of relevant ECF and colorectal findings are relatively low in symptomatic low-risk patients. By use of CTC as a singular examination, especially in elderly patients, most colonoscopies can be avoided with the benefit of diagnosing relevant ECF without introducing substantial over-diagnosis.

Virtual colonoscopy for primary screening. The future is now.

Virtual colonoscopy (VC) is a minimally invasive tool that utilizes modern CT technology for colorectal evaluation. Since its inception in 1994, VC has continued to rapidly evolve and improve as a diagnostic screening tool. Early success using primary two-dimensional (2D) detection in polyp-rich cohorts was followed by disappointing results in low prevalence populations. Subsequent introduction of the three-dimensional (3D) endoluminal display for primary polyp detection and oral contrast tagging has transformed VC into an effective primary screening tool. This state-of-the-art VC technique has already proven to be a viable enterprise when combined with existing optical colonoscopy practice. More widespread implementation of VC screening faces multiple challenges, but these are all greatly overshadowed by the immediate need for increased participation in effective colorectal screening. Given its relatively noninvasive nature and the wide availability of CT, VC holds significant potential for addressing a very important yet preventable public health concern. This review will cover current VC technique, compare the existing multi-center VC trials, discuss issues related to primary VC screening, and briefly update the progress of our VC screening program.

Intense uptake of technetium-99m-MDP in primary breast adenocarcinoma with sarcomatoid metaplasia.

Focal soft-tissue accumulation of bone-seeking radiopharmaceuticals has many causes but is usually less intense than skeletal activity. Extraskeletal new bone formation, as seen in myositis ossificans and extraskeletal osteosarcoma, represents an exception where markedly increased uptake can be seen. Technetium-99m-MDP uptake in primary breast carcinoma has been recently investigated using scintamammographic techniques to differentiate malignant from benign lesions. The mechanism of uptake remains unclear but is likely multifactorial and nonspecific. We present a case of primary breast carcinoma with florid 99mTc-MDP activity relative to normal bone. Tumor histopathology in this patient demonstrates malignant new bone formation as the likely mechanism for the marked radiotracer avidity.

Congenital absence of the pericardium confirmed by spontaneous pneumothorax.

This article describes a case of complete absence of the left pericardium which was diagnosed on the chest radiograph and subsequently confirmed on computed tomography and thoracoscopy. Diagnostic confidence was bolstered by the presence of pneumopericardium which communicated via the defect with a spontaneous left pneumothorax. The clinical and imaging findings of pericardial absence are reviewed.

Collecting duct carcinoma arising in a solitary kidney: imaging findings.

Collecting duct carcinoma is an aggressive malignancy derived from the renal medulla. Imaging features suggestive of this diagnosis include a medullary origin, hypovascularity, and an infiltrative growth pattern. A case of collecting duct carcinoma with unsuspected contralateral renal agenesis is presented.

Three-phase skeletal scintigraphy in gouty arthritis: an example of potential diagnostic pitfalls in radiopharmaceutical imaging of the extremities for infection.

The three-phase bone scan has been shown to be useful in the diagnosis of osteomyelitis, with a high sensitivity and specificity under optimal conditions. However, there are many causes of focally-increased uptake of Tc-99m diphosphonates in the extremities that may mimic infection, especially when there is increase on all three phases. Radiolabeled leukocyte scintigraphy is often performed in this clinical setting, although many pitfalls resulting in false-positive scans still remain. The authors present three cases of gouty arthritis in which skeletal scintigraphy illustrates this lack of specificity. Further causes of increased extremity uptake are reviewed, with attention to those that have been reported to show an increase on all three phases of the bone scan. Additional factors that can improve the specificity of the bone scan are discussed, as are the panoply of more recent scintigraphic approaches aimed at distinguishing infection from aseptic inflammation in the extremity. Unfortunately, no nuclear medicine procedure to date has proven itself to be reliably specific for infection.

Giant adrenal myelolipoma presenting with spontaneous hemorrhage. CT, MR and pathology correlation.

We report a case of a 56-year old symptomatic patient found to have a giant adrenal myelolipoma with hemorrhage. The characteristic CT and MR features and their aid in the diagnosis are demonstrated. We propose a definition of the often quoted term "giant" adrenal myelolipoma.