Non-contrast Studies Research Articles

Acute Genital Edema during Peritoneal Dialysis: A Review for Surgeons

Acute genital edema (AGE) is an infrequent but disruptive complication in patients on continuous ambulatory peritoneal dialysis. It is a common manifestation of dialysate leakage caused by inguinal, umbilical, femoral, or incisional hernias; peritoneal tears; leaks around the dialysis catheter; trauma; fluid overload; and malignancy. The evaluation of AGE begins with a history and physical exam. However, the physical exam in these patients is often indeterminate. Several diagnostic measures exist to evaluate and guide management of AGE occurring during continuous ambulatory peritoneal dialysis but little agreement exists on an optimum method. We have conducted a review of the literature on the evaluation and management of AGE and present a summary of the data. CT peritoneography and peritoneal scintigraphy have been used extensively to evaluate AGE although no comparative studies exist. MRI peritoneography has also been described. CT peritoneography offers more anatomical detail but may not be as sensitive as peritoneal scintigraphy in detecting a peritoneal fluid leak as the cause for AGE. CT is also more costly and subjects the patient to more radiation. MRI is a noncontrast study without radiation risk, but has not been studied to the same degree. If testing is equivocal or bilateral hernias are suspected, diagnostic laparoscopy is helpful and can be combined with hernia repair. Whether the etiology is a leak or tear, low-volume peritoneal dialysis (PD) or cessation of PD for two to four weeks will allow closure. However, hernias almost always require operative repair with mesh usually without disrupting PD.

Cerebral Angiography for Evaluation of Patients with CT Angiogram-Negative Subarachnoid Hemorrhage: An 11-Year Experience.

CT angiography is increasingly used to evaluate patients with nontraumatic subarachnoid hemorrhage given its high sensitivity for aneurysms. We investigated the yield of digital subtraction angiography among patients with SAH or intraventricular hemorrhage and a negative CTA. An 11-year, single-center retrospective review of all consecutive patients with CTA-negative SAH was performed. Noncontrast head CT, CTA, DSA, and MR imaging studies were reviewed by 2 experienced interventional neuroradiologists and 1 neuroradiologist. Two hundred thirty patients (mean age, 54 years; 51% male) with CTA-negative SAH were identified. The pattern of SAH was diffuse (40%), perimesencephalic (31%), sulcal (31%), isolated IVH (6%), or identified by xanthochromia (7%). Initial DSA yield was 13%, including vasculitis/vasculopathy (7%), aneurysm (5%), arteriovenous malformation (0.5%), and dural arteriovenous fistula (0.5%). An additional 6 aneurysms/pseudoaneurysms (4%) were identified by follow-up DSA, and a single cavernous malformation (0.4%) was identified by MRI. No cause of hemorrhage was identified in any patient presenting with isolated intraventricular hemorrhage or xanthochromia. Diffuse SAH was due to aneurysm rupture (17%); perimesencephalic SAH was due to aneurysm rupture (3%) or vasculitis/vasculopathy (1.5%); and sulcal SAH was due to vasculitis/vasculopathy (32%), arteriovenous malformation (3%), or dural arteriovenous fistula (3%). DSA identifies vascular pathology in 13% of patients with CTA-negative SAH. Aneurysms or pseudoaneurysms are identified in an additional 4% of patients by repeat DSA following an initially negative DSA. All patients with CT-negative SAH should be considered for DSA. The pattern of SAH may suggest the cause of hemorrhage, and aneurysms should specifically be sought with diffuse or perimesencephalic SAH.

How Much Is That Head CT? Price Transparency and Variability in Radiology

PurposeTo extend the investigation of price transparency and variability to medical imaging. MethodsEighteen upper-tier academic hospitals identified by U.S. News & World Report and 14 of the 100 largest private radiology practices in the country identified by the Radiology Business Journal were contacted by telephone between December 2013 and February 2014 to determine the cash price for a noncontrast head CT. The price for a noncontrast head CT was chosen to assess price transparency in medical imaging because it represents a standard imaging examination with minimal differences in quality. ResultsFourteen upper-tier academic hospitals (78%) and 11 private practices (79%) were able to provide prices for a noncontrast head CT. There was no significant difference between the proportions of upper-tier academic hospitals and private practices that were able to provide prices for a noncontrast head CT (P = .96). The average total price for the upper-tier academic hospitals was $1,390.12 ± $686.13, with the price ranging from $391.62 to $2,015. The average total price for the private practices was $681.60 ± $563.58, with the total price ranging from $211 to $2,200. ConclusionsPrices for a noncontrast head CT study were readily available from the vast majority of upper-tier academic hospitals and private practices, although there was tremendous variation in the price estimates both within and between the upper-tier academic hospitals and private practices. Routine medical imaging thus appears to be more price transparent compared with other health care services.

Influence of technical parameters on epicardial fat volume quantification at cardiac CT

ObjectivesTo systematically analyze the influence of technical parameters on quantification of epicardial fat volume (EATV) at cardiac CT. Methods153 routine cardiac CT data sets were analyzed using three-dimensional pericardial border delineation. Three image series were reconstructed per patient: (a) CTAD: coronary CT angiography (CTA), diastolic phase; (b) CTAS: coronary CTA, systolic phase; (c) CaScD: non-contrast CT, diastolic phase. EATV was calculated using three different upper thresholds (−15HU, −30HU, −45HU). Repeated measures ANOVA, Spearman's rho, and Bland Altman plots were used. ResultsMean EATV differed between all three image series at a −30HU threshold (CTAD 87.2±38.5ml, CTAS 90.9±37.7ml, CaScD 130.7±49.5ml, P<0.001). EATV of diastolic and systolic CTA reconstructions did not differ significantly (P=0.225). Mean EATV for contrast enhanced CTA at a −15HU threshold (CTAD15 102.4±43.6ml, CTAS15 105.3±42.3ml) could be approximated most closely by non-contrast CT at −45HU threshold (CaScD45 105.3±40.8ml). The correlation was excellent: CTAS15–CTAD15, rho=0.943; CTAD15–CaScD45, rho=0.905; CTAS15–CaScD45, rho=0.924; each P<0.001). Bias values from Bland Altman Analysis were: CTAS15–CTAD15, 4.9%; CTAD15–CaScD45, −4.3%; CTAS15–CaScD45, 0.6%. ConclusionsMeasured EATV can differ substantially between contrast enhanced and non-contrast CT studies, which can be reconciled by threshold modification. Heart cycle phase does not significantly influence EATV measurements.

Appropriate use criteria and CTCA - is there a role in asymptomatic individuals?

Background: Society for Cardiovascular CT appropriate use criteria for Computed Tomographic Coronary Angiography (CTCA) advise against its use in those without symptoms of coronary artery disease (CAD). We sought to evaluate the use of CTCA against the appropriate use criteria and examine the findings in asymptomatic patients. Methods: Records were reviewed of 731 consecutive CTCA studies performed at a single institution prior to December 2014. Request forms and reports were retrieved. Results: The mean age was 54 with 56% of male gender. The most common indication was for detection of CAD in symptomatic patients (63.2%) Only 29 out of 731 patients were asymptomatic (4.0%), with the most common indication being investigation of non-specific ECG changes or minor troponin elevation (52%). The remainder were at high risk of CAD due to multiple risk factors or a strong family history for premature coronary artery disease or sudden cardiac death. Of the CTCA scans in asymptomatic individuals, 45% were normal, non-obstructive plaque was seen in 38%, and obstructive lesions were seen in 17%. All asymptomatic individuals with abnormal scans had coronary calcification identifiable on a non-contrast study. Conclusion: In our institution, 96% of all CTCA requests fulfilled appropriate use criteria. In the other 4%, who were asymptomatic high risk individuals, a majority of patients (55%) were found to have non-obstructive/obstructive plaque but in each case this could have been identified on calcium scoring alone. Our findings suggest ongoing adherence to CTCA appropriate use criteria.

High-spatial- and high-temporal-resolution dynamic contrast-enhanced MR breast imaging with sweep imaging with Fourier transformation: a pilot study.

To report the results of sweep imaging with Fourier transformation (SWIFT) magnetic resonance (MR) imaging for diagnostic breast imaging. Informed consent was obtained from all participants under one of two institutional review board-approved, HIPAA-compliant protocols. Twelve female patients (age range, 19-54 years; mean age, 41.2 years) and eight normal control subjects (age range, 22-56 years; mean age, 43.2 years) enrolled and completed the study from January 28, 2011, to March 5, 2013. Patients had previous lesions that were Breast Imaging Reporting and Data System 4 and 5 based on mammography and/or ultrasonographic imaging. Contrast-enhanced SWIFT imaging was completed by using a 4-T research MR imaging system. Noncontrast studies were completed in the normal control subjects. One of two sized single-breast SWIFT-compatible transceiver coils was used for nine patients and five controls. Three patients and five control subjects used a SWIFT-compatible dual breast coil. Temporal resolution was 5.9-7.5 seconds. Spatial resolution was 1.00 mm isotropic, with later examinations at 0.67 mm isotropic, and dual breast at 1.00 mm or 0.75 mm isotropic resolution. Two nonblinded breast radiologists reported SWIFT image findings of normal breast tissue, benign fibroadenomas (six of six lesions), and malignant lesions (10 of 12 lesions) concordant with other imaging modalities and pathologic reports. Two lesions in two patients were not visualized because of coil field of view. The images yielded by SWIFT showed the presence and extent of known breast lesions. The SWIFT technique could become an important addition to breast imaging modalities because it provides high spatial resolution at all points during the dynamic contrast-enhanced examination.

Pitfalls of ophthalmic radiographic imaging.

Ophthalmologists are dependent on computed tomography (CT) and MRI to aid in the diagnosis and management of patients with orbital and visual conditions. Pitfalls in the imaging process can lead to inefficient care or patient harm. This review summarizes these problems and provides methods to reduce imaging errors. There has been exponential growth in the number of radiographic scans performed, resulting in increased awareness of the risks from medical radiation. Strategies to minimize radiation exposure include reducing the need for sequential scans, using appropriate technology, and substituting MRI for CT. Contrast administration can be associated with systemic reactions, renal disease, and thyroid dysfunction. Scan interpretation errors are reduced by the ophthalmologist reviewing the study and communication with the radiologist. Medical radiation exposure can be reduced by initially ordering the appropriate scan and substituting MRI for CT when possible. MRI is contraindicated in patients with certain implants and metallic foreign bodies. Noncontrast studies are adequate to evaluate many conditions and some patients should not receive contrast. Imaging errors can be reduced by the ophthalmologist personally reviewing the orbital scans and correlating the results with the clinical findings.

Utility of CT head in the acute setting: value of contrast and non-contrast studies.

To examine the added diagnostic value of emergent contrast enhanced CT head (CECTH) in patients who present to the emergency department (ED) with acute non-traumatic symptoms referable to the brain, and to assess the financial implications of CECTH in the emergent setting. We queried healthcare data for head CTs ordered by our ED between January 2008 and December 2010. Those who presented to the ED with non-traumatic neurologic disturbances were included. All traumatic head injury cases were excluded. Two board certified radiologists with fellowship training who were blinded to patient history and physical findings, independently reviewed all non-contrast computed tomography of the head (NCTH) and CECTH images. CECTH's were read following abnormal NCTH's, and findings were recorded as normal or abnormal. In our investigation, 379 patients-210 (55 %) females and 169 (45 %) males-met the inclusion criteria. Common indications for head CT included: headache 183 (48 %); dizziness 73 (19 %); altered mental status 49 (13 %); and seizure 38 (10 %). The mean age of study subjects was 47 (±29) years. Two hundred sixty-one (69 %) of all patients scanned showed no abnormality. One hundred eighteen (31 %) of 379 patients had abnormal scans. We encountered 1 abnormal CECTH on which NCTH was normal. Cost of CECTH was $465 and NCTH was $385. Head CT in ED non-traumatic neurological presentations with CECTH is not generally indicated and represents a calculable cost savings in the management of these patients.

The Impact of Computed Tomography of the Chest on the Management of Patients in a Medical Intensive Care Unit.

To understand whether chest computed tomographies (CTs) have utility in a medical intensive care unit (MICU) population as previously noted in nonmedical critically ill patients. We conducted a retrospective cohort study of patients receiving chest CTs in the MICU at an urban, academic institution. Indications for, findings on, and care changes made after chest CT were obtained. We identified patient characteristics associated with having a care change clearly related to the CT using multivariate regression. We evaluated 134 patients; 64 (47.8%) had a chest CT with intravenous contrast. Common findings included pulmonary consolidation (46.3%), nonconsolidative pulmonary parenchymal disease (29.1%), and pleural effusion (35.1%). Of the chest CTs, 23.9% were followed by changes in management clearly related to the study. Use of intravenous contrast was associated with increased odds of having a care change (adjusted odds ratio [95% confidence interval [CI] versus noncontrast study: 3.14 [1.18-8.37], P = .022) and having the CT performed 1 or 2 days after ICU admission versus on the day of ICU admission was associated with lower odds of a care change (odds ratio [95% CI]: 0.29 [0.09-0.99], P = .048). Less than one-quarter of chest CTs in the MICU result in management. Intravenous contrast-enhanced CTs and CTs done on the day of ICU admission have increased odds of utility.

Diagnostic accuracy of noncontrast MRI for detection of glenohumeral cartilage lesions: a prospective comparison to arthroscopy

The purpose of this study was to determine the prevalence of glenohumeral articular cartilage lesions in patients with rotator cuff tendinopathy and to assess the accuracy of noncontrast magnetic resonance imaging (MRI) in detecting these defects compared with the "gold standard" of arthroscopy. Noncontrast MRI studies obtained in 84 consecutive patients undergoing shoulder arthroscopy for rotator cuff tendinopathy (mean age, 54.8 years; range, 17-82 years) were prospectively evaluated for glenohumeral cartilage lesions. Two fellowship-trained, experienced musculoskeletal radiologists were blinded from the arthroscopic findings and independently evaluated the glenoid and humeral head cartilage on 2 separate occasions. At arthroscopy, cartilage lesions of the humeral head were detected in 23 patients (frequency, 27.4%), and glenoid cartilage lesions were found in 20 patients (frequency, 23.8%). For detection of a humeral lesion on MRI, the radiologists' combined accuracy was 78%, sensitivity was 43%, and specificity was 91%. The combined accuracy for detection of glenoid lesions on MRI was 84%, sensitivity was 53%, and specificity was 93%. Combining the readers, low-grade lesions (International Cartilage Repair Society grades 1 and 2) of the glenoid and humerus were read as negative on MRI in 63% and 86% of cases, respectively. Overall accuracy of noncontrast MRI for detection of glenohumeral articular cartilage lesions is good; however, interpretation is reader dependent, and accuracy is significantly reduced for detection of low-grade lesions. On the basis of these findings, we recommend that patients with rotator cuff tendinopathy undergoing arthroscopy be informed that the presence and severity of cartilage lesions may be underestimated on MRI.

Glenohumeral Articular Cartilage Lesions: Prospective Comparison of Non-Contrast Magnetic Resonance Imaging and Findings at Arthroscopy

The purpose of this study was to assess the diagnostic sensitivity, specificity, accuracy, negative predictive value (NPV), positive predictive value (PPV), and test-retest reliability of magnetic resonance imaging (MRI) for detecting cartilage abnormalities of the glenohumeral joint in comparison with the gold standard of diagnostic arthroscopy. Forty-four patients with a preoperative non-contrast MRI study of their affected shoulder underwent arthroscopy by one surgeon for rotator cuff tendinopathy from 2009 to 2010. Articular cartilage defects were prospectively recorded and graded according to the International Cartilage Repair Society classification system at the time of arthroscopy. One year after surgery, the preoperative MRI were reviewed by a board-certified radiologist and the treating surgeonfor articular cartilage defects of both the humeral head and the glenoid. Sensitivity, specificity, accuracy, and test-retest reliability were calculated. At arthroscopy, 43% of the shoulders were found to have articular cartilage defects. When the readers' findings were combined, the sensitivity of detecting humeral lesions on MRI was 32%; specificity, 80%; accuracy, 63%; PPV, 57%; and NPV, 66%. The sensitivity of detecting glenoid lesions was 31%; specificity, 86%; accuracy, 76%; PPV, 33%; and NPV, 85%. This study finds that the overall accuracy of MRI in detecting articular cartilage damage in patients with the clinical diagnosis of subacromial pathology is moderate. Level II, development of diagnostic criteria based on consecutive patients with universally applied reference "gold" standard.

Effect of a preauthorization policy on the utilization rate of after-hours emergency department neuroradiology computed tomography

To evaluate the impact of an emergency department (ED) automatic preauthorization policy on after-hours utilization of neuroradiology computed tomography (CT). All CT studies of the head with contrast facial bones, orbits, spine, and neck requested through the ED and performed between January 1, 2004, and December 31, 2010, were reviewed. The preauthorization policy was instituted on February 25, 2008. A control group of noncontrast CT head studies was used for comparison. Pre- and postpolicy implementation utilization rates were compared between the control group of noncontrast CT head studies and the study group neuroradiology CT studies. During the study period, 408,501 ED patient visits occurred and 20,703 neuroradiology CT studies were carried out. The pre- and postimplementation groups of noncontrast CT head scans totalled 7,474 and 6,094, respectively, whereas the pre- and postimplementation groups of all other neuroradiology CT studies totalled 3,833 and 3,302, respectively. The CT utilization between the two groups did not differ significantly: the noncontrast head group pre- and postpolicy implementation increased by 0.31 to 3.41%, whereas the utilization of all other neuroradiology CT studies increased by 0.22 to 1.84% (p value = 0.061 for a difference between groups). Implementation of an automatic preauthorization policy for after-hours neuroradiology CT studies did not result in a statistically significant increase in CT utilization. This suggests that concerns regarding the negative effects of such policies may be unfounded, and further research in this area is warranted.

Radiation exposure in patients with subarachnoid hemorrhage: a quality improvement target

The care of patients with subarachnoid hemorrhage (SAH) has improved dramatically over the last decades. These gains are the result of improved microsurgical, endovascular, and medical management techniques. This intensive management subjects patients to multiple radiographic studies and thus increased radiation exposure. As greater understanding of the risks of radiation exposure develops, physicians must be better equipped to balance the need for optimal SAH management with the minimization of patient exposure to radiation from imaging studies. The goal in the current study was to determine if there is an opportunity for a reduction in radiation dose without a change in the quality of treatment in patients with SAH. A retrospective chart review of all patients hospitalized for SAH at the Brigham and Women's Hospital in the period from January 1, 2009, to August 31, 2010, was performed. The authors calculated cumulative and imaging study-specific radiation doses, determined the time of day that imaging studies were performed, and surveyed neurosurgeons regarding issues surrounding imaging-related radiation exposure. The data for 77 patients were analyzed. The mean cumulative radiation dose during hospitalization was 2.76 Gy per patient (range 0.46-8.32 Gy). The mean radiation exposure from each CT, CT angiography (CTA), and angiography study was 0.08, 0.29, and 0.77 Gy (ranges 0.02-0.40, 0.15-0.99, and 0.11-4.36 Gy, respectively). Subgroup analysis of the top quartile of patients in terms of total radiation dose revealed a mean cumulative radiation dose of 4.78 Gy (range 3.42-8.32 Gy), mean cumulative number of CT and CTA scans of 14, and mean CT or CTA scan per day of 0.5 (maximum 0.8). Seventeen percent of the noncontrast head CT studies were performed just prior to morning rounds, more than double the 8% expected rate at random. Thirty-four percent of the repeat noncontrast head CTs did not show any change between scans, as documented on radiology reports. When surveyed, a majority of neurosurgeons incorrectly estimated the radiation dose typically received from CT, CTA, and angiography studies, and 65% asserted that radiation exposure is "not important" or only "somewhat important" when considering whether to order an imaging study. Study findings suggested that patients with SAH have significant imaging-related exposure to radiation. The authors believe it is possible to continue the current improved outcomes in SAH with a significant reduction in radiation exposure from imaging studies. This analysis highlights the significance of accurate assessment of radiation exposure as a quality improvement target.

Can Coronary Artery Anomalies Be Detected on CT Calcium Scoring Studies?

To determine whether coronary artery anomalies can be detected on noncontrast computed tomography (CT) coronary artery calcium scoring (CCS) studies. A total of 126 patients (mean age 62 years; 35 women) underwent noncontrast CCS and contrast enhanced coronary CT angiography (cCTA). Thirty-three patients were diagnosed with a coronary anomaly on cCTA, whereas coronary anomalies were excluded in 93. Two observers (reader 1 [R1] and reader 2 [R2]), blinded to patient information independently evaluated each CCS study for: 1) visibility of coronary artery origins, 2) detection of coronary anomalies, and 3) benign or malignant (ie, interarterial) course. Using cCTA as the reference standard, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of CCS studies for detecting coronary anomalies were calculated. Of the 33 coronary anomalies, 16 were benign and 17 malignant. Based on noncontrast CCS studies, R1 and R2 correctly identified the left main origin in 123/126 (97.6%) and 121/126 (96%) patients; the left anterior descending origin in 125/126 (99.2%) and 122/126 (96.8%); the circumflex origin in 120/126 (95.2%) and 105/126 (83.3%); and the right coronary artery origin in 117/126 (92.9%) and 103/126 (81.7%), respectively. R1 and R2 identified 34 and 27 coronary anomalies and classified 19 and 15 as malignant, respectively. Interobserver reproducibility for detection of coronary anomalies was good (k = 0.76). Interobserver agreement for detection of malignant variants was even stronger (k = 0.80). On average, coronary artery anomalies were diagnosed with 85.2% sensitivity, 96.4% specificity, 90.5% PPV, and 94.1% NPV on noncontrast CCS studies. Benign and malignant coronary artery anomalies can be detected with relatively high accuracy on noncontrast-enhanced CCS studies. CCS studies should be reviewed for signs of coronary artery anomalies in order to identify malignant variants with possible impact on patient management.

Sensitivity of Preoperative Magnetic Resonance Imaging and Magnetic Resonance Arthrography in Detection of Panlabral Tears of the Glenohumeral Joint

The purpose of this study was to evaluate the sensitivity of preoperative magnetic resonance imaging (MRI) in detecting combined lesions of the glenoid labrum involving tears of the anterior, posterior, and superior labrum. Preoperative MRI findings were available in 46 cases of arthroscopic repair of combined tears of the anterior, posterior, and superior labrum (mean age, 31 years), including 23 noncontrast MRI studies and 24 magnetic resonance (MR) arthrography studies (1 patient had both). MRI findings were compared with the status of the labrum at the time of arthroscopy, and the sensitivity of MRI was determined. MRI showed evidence of combined lesions of the anterior, posterior, and superior labrum in only 10 of 47 studies (21.3%). Only 2 of 23 (8.7%) tears were detected by noncontrast MRI, compared with 8 of 24 (33.3%) by MR arthrography (P= .07). Non-contrast MRI showed evidence of labral pathology in more than one direction in 10 of 23 studies (43.5%), compared with 20 of 24 MR arthrography studies (83.3%) (P= .006). Noncontrast MRI showed no evidence of a labral tear in 3 of 23 patients (13.0%), whereas no MR arthrogram was completely negative for a labral tear (0%) (P= .11). Combined tears of the anterior, posterior, and superior glenoid labrum are infrequent injuries that are typically not completely defined by either noncontrast MRI or MR arthrography. Level III, diagnostic study.

Human non-contrast T1 values and correlation with histology in diffuse fibrosis

BackgroundAortic stenosis (AS) leads to diffuse fibrosis in the myocardium, which is linked to adverse outcome. Myocardial T1 values change with tissue composition.ObjectiveTo test the hypothesis that our recently developed...

Image Quality and Radiation Dose Comparison between Filtered Back Projection and Adaptive Statistical Iterative Reconstruction in Non-contrast Head CT Studies

Purpose: The goal of the study was to compare the total radiation dose and subjective image quality between conventional Filtered Back Projection (FBP) and Adaptive Statistical Iterative Reconstruction (ASIR) in non-contrast head CT. Method: Forty seven patients underwent non contrast head CT with image reconstruction using 100% FBP. The same set of patients underwent subsequent non contrast head CT within 6 months using combination of ASIR and FBP reconstruction. Institutional Review Board approval was obtained. Objective assessment of total radiation dose was obtained by measuring the dose length product (DLP) and effective radiation dose. Subjective image quality was assessed by 2 attending radiologists who were blinded to the scanning technique. All images were graded for sharpness, image noise and overall image quality on a 5 point Likert scale. Both subjective and objective measurements from the two sets of images were compared. Paired Student’s t-Test was used for statistical analysis. Results: There was a significant reduction in DLP with the application ASIR from 1781.7 (310) to 1098.9 (SD 281.4) mGy-cm (p<0.01), resulting in mean total dose reduction of 38.4%. The total effective dose also showed similar reduction from 3.9 (SD 0.68) to 2.4 (SD 0.62) mSv (P<0.01). Subjective score for image noise was 4.44 (SD 0.43) and 4.40 (SD 0.48), before and after application of ASIR, respectively (p=0.59). Overall image quality scores were 4.87 (SD 0.33) and 4.85 (0.36) before and after application of ASIR, respectively (p=0.12). Subjective scores for image sharpness decreased after application of ASIR from 4.94 (SD 0.24) to 4.77 (SD 0.47) (p=0.04) Conclusion: Compared to conventional FBP reconstruction, combination of ASIR with FBP reconstruction results in significant reduction in total radiation dose without affecting the overall image quality in non-contrast head CT.

Evaluation of acute renal colic: a comparison of non-contrast CT versus 3-T non-contrast HASTE MR urography

With the introduction of a 3-T scanner, magnetic resonance urography (MRU) may be an alternative imaging modality for evaluation of acute renal colic. We performed a prospective study to compare the performance of computed tomography (CT) with half-Fourier single shot turbo spin-echo (HASTE) MRU in the evaluation of patients with suspected renal colic. Patients presenting to the emergency department with acute renal colic were eligible for inclusion. Following a standard CT stone evaluation, patients underwent a non-contrast HASTE MRU study with a 3-T scanner. The presence of perinephric fluid, hydronephrosis, ureteral obstruction, and calculus was assessed. A total of 22 patients completed the study. Twenty (91%) were diagnosed with an upper tract stone by radiographic findings. MRU detected a discrete stone in 50% of the patients with stones detected by CT. Perinephric fluid was noted in 12 MRUs, compared to 7 CTs. Using CT as the reference standard, the combination of stone or perinephric fluid and ureteral dilation gave MRU a sensitivity of 84%, specificity of 100%, and accuracy of 86% (95% CI 0.72-1.0). HASTE MRU with a 3-T MR scanner can reliably detect the presence of upper urinary tract obstruction. Although CT imaging remains the superior modality with which to detect calculi, MRU detects a greater number of secondary signs of upper tract obstruction. For situations in which the use of ionizing radiation is undesirable, MRU is a reasonable imaging alternative.

CT imaging features of acinar cell carcinoma and its hepatic metastases.

To evaluate and describe the computed tomography features of pure acinar cell carcinoma (ACC) and its liver metastases. Thirty patients were evaluated. Two radiologists evaluated imaging findings for each tumor for size, location, internal density, enhancement, tumor calcifications, pancreatic, and common biliary ductal obstructions and metastases. 70 % were male. Fourteen tumors were located in the pancreatic head, 14 in the tail, one in the neck, and one in the uncinate process. Abdominal pain was the most common presenting symptom (93 %), 20 % had pancreatitis and 17 % had obstructive jaundice. The average tumor size was 7 cm, 97 % of tumors were solid, well circumscribed (73 %); isodense to normal pancreatic parenchyma (40 %) on the non-contrast study, hypodense on the arterial (47 %), and hypodense on the portal venous (37 %) phase. 30 % patients had pancreatic ductal dilation, 10 % had pancreatic ductal ingrowth, 6 % had calcifications, and 20 % had central necrosis, and 31 % (5/16) showed biliary ductal dilation. At presentation, 50 % had metastatic adenopathy and 40 % patients had liver metastases, which typically were well circumscribed, hypoattenuating to the hepatic parenchyma on all the phases of contrast enhancement and had a lobulated margin. ACCs of the pancreas often present as large, well circumscribed, solid masses commonly in males. Despite their large size, they may not cause CBD obstruction.

Do we really need contrast agents?

The exciting possibility of achieving diagnostic breast magnetic resonance examinations without administration of a contrast agent could make breast MRI a more accessible clinical tool, especially for screening applications. Eliminating the use of contrast would not only benefit the patient population for whom gadolinium contrast agents are contraindicated, but could facilitate and improve standard non-enhanced acquisitions acquired as part of a routine DCE-MRI study. Non-contrast examinations can be appropriate for either a screening or diagnostic application, and additional applications include parenchymal imaging for risk assessment and assessment of hormonal therapy response. Previous reports have investigated the use of diffusion-weighted and STIR imaging for non-contrast MR studies [1]. We have investigated the use of noncontrast enhanced high spectral and spatial resolution (HiSS) MRI. HiSS MRI technique improves image quality by eliminating some of the imaging side-effects of contrast agent administration which may affect lesion and/or parenchymal visualization, improving separation of fat and water signals, and reducing chemical shift blurring by imaging individual components of the water resonance. 1. Background