Daniel Cornfeld

Impact of Adaptive Statistical Iterative Reconstruction (ASIR) on Radiation Dose and Image Quality in Aortic Dissection Studies: A Qualitative and Quantitative Analysis

OBJECTIVE The purpose of the study was to quantify the radiation dose reduction achieved when imaging the aorta using Adaptive Statistical Iterative Reconstruction (ASIR) and to determine if this has an effect on image quality. MATERIALS AND METHODS We retrospectively reviewed 31 CT angiography examinations of the thoracic and abdominal aorta performed with ASIR and 32 consecutive similar examinations performed without ASIR. Volume CT dose index (CTDI(vol)), dose-length product (DLP), aortic enhancement at multiple levels, aorta-to-muscle contrast-to-noise ratio at multiple levels, and subjective image quality were compared between the two groups. RESULTS The mean CTDI(vol) and DLP were significantly lower for the studies performed with ASIR versus studies without ASIR (15.6 vs 21.5 mGy, with an average difference of 5.8 mGy [95% CI 2.3-9.4 mGy] and 818 vs 1075 mGy × cm with an average difference of -257 mGy × cm [54-460 mGy × cm], respectively). Aortic enhancement, aortic signal-to-noise ratio, and aortic to muscle contrast-to-noise ratio were not different between the two groups. Subjectively, one reviewer preferred the non-ASIR images and one found the images equivalent. Both reviewers believed the images were of diagnostic quality. CONCLUSION A 29% decrease in CTDI(vol) and a 20% decrease in DLP were obtained in scans with ASIR compared with scans without ASIR, without a quantitative loss of image quality.

MRI appearance of mesenchymal tumors of the uterus

PURPOSE Uterine leiomyomas are the most common uterine neoplasms. Statistically, a uterine mass with unusual imaging features is more likely to represent a leiomyoma than other uncommon uterine mesenchymal neoplasms such as leiomyosarcoma or endometrial stromal tumors. Several prior studies have attempted to identify objective imaging characteristics that differentiate these entities. The purpose of this study was to test these criteria on our patient population. METHODS AND MATERIALS This retrospective study was approved by the institutional Human Investigations Committee and was performed in compliance with HIPAA regulations. Four patients with uterine leiomyosarcoma, two with stromal tumors of uncertain malignant potential (STUMP), one with endometrial stromal sarcoma, and two with mixed endometrial stromal and smooth muscle tumors were included in the study. Seventeen additional control cases of leiomyomas were selected as controls. Cases were blindly evaluated by two experienced readers. Objective criteria included T1 and T2 signal characteristics, enhancement pattern, the presence of cystic changes, and ill defined margins. Subjective criteria included individual reader gestalt. All cases had pathologic correlation. RESULTS None of the objective criteria were associated with the presence or absence of uterine mesenchymal neoplasm. Ill defined margins came closest to having statistical significance (p=0.06). Reader gestalt was statistically associated with the presence of mesenchymal neoplasm for one of our readers (p=0.02) but not for the other (p=0.07). CONCLUSION We found poor accuracy for objective imaging criteria in distinguishing leiomyomas with atypical imaging features from more clinically significant uterine mesenchymal neoplasms.

Dynamic Contrast-Enhanced Breast MR Imaging

This article discusses the basic principles of dynamic contrast-enhanced MR imaging (DCE-MR imaging) of the breast, including technical parameters, image acquisition, and image interpretation. Clinical DCE-MR imaging of the breast has undergone considerable growth from a once investigational technique to an important clinical tool in widespread use. Progress in MR technology and refinement of MR imaging parameters now allow for concurrent acquisition of high-spatial-resolution and adequate-temporal-resolution images, which are necessary for accurate assessment of breast lesion morphology and qualitative kinetic analysis. More advanced DCE-MR imaging techniques involving higher-temporal-resolution images and rigorous quantitative analysis of the time signal enhancement curves are currently an area of research.

Pelvic imaging using a T1W fat-suppressed three-dimensional dual echo Dixon technique at 3T.

To compare two T1‐weighted (T1W) fat‐suppressed sequences for 3D breath‐hold pre‐ and postcontrast fat‐suppressed T1W imaging of the female pelvis at 3T.

Does a combination of dose modulation with fast gantry rotation time limit CT image quality

OBJECTIVE The objective of our study was to determine the degree to which CT tube current saturates (tube current reaching its maximal capacity) if dose modulation and fast gantry rotation speeds are used when imaging the abdomen and pelvis and to determine whether saturated tube current affects image quality. MATERIALS AND METHODS We evaluated the CT scans of patients who underwent imaging of the abdomen and pelvis using dose modulation and the fastest gantry rotation time available on two different CT scanners. Ninety-five patients were scanned with a 64-MDCT scanner (noise index, 11; tube rotation speed, 0.5 second) with a maximal x-ray tube capacity of 695 mA. Ninety-four patients were scanned with a 16-MDCT scanner (noise index, 11.6; tube rotation speed, 0.6 second), which has a maximal x-ray tube capacity of 440 mA. The total number of images per examination, total number of images obtained at saturated tube current, image noise (SD of fluid attenuation), and patient width were recorded. A qualitative evaluation of image quality, with images obtained below and at the maximal tube current grouped separately, was performed by two independent radiologists who were not blinded to the type of scanner used using a scale of from 1 (best) to 4 (worst). Statistical analyses included the Kruskal-Wallis one-way analysis of ranks test for nonparametric ordinal data, the unpaired two-tailed Students t test, and the chi-square test. RESULTS For images obtained with the stronger x-ray tube (maximum tube current = 695 mA), the average number of axial images per examination was 87.6. In 34 of 95 (36%) patients, at least one image was acquired with the tube current saturated. The average image noise was 12.4 H. Subjective evaluation yielded an average image quality score of 1.2 for images below saturated tube current and 1.2 for images at saturated tube current. For images obtained with the weaker x-ray tube (maximum tube current = 440 mA), the average number of axial images per examination was 88.9. In 84 of 94 (89%) patients, at least one image was acquired with the tube current saturated. The average image noise was 16.8 H. Qualitative evaluation showed average image quality scores of 1.3 and 1.8 for images below and at the saturated tube current, respectively. The percentage of images acquired at the saturated tube current was significantly greater for the weaker x-ray tube than the stronger x-ray tube (p < 0.0001), and qualitative analysis of images obtained at saturated tube current showed significantly decreased quality for the weaker x-ray tube when compared with images obtained with nonsaturated current (p = 0.001). CONCLUSION On the MDCT scanners investigated, when dose modulation is combined with fast tube rotation times, tube current saturation occurs with weaker x-ray tubes resulting in deterioration of image quality.

Clinical Uses of Time-Resolved Imaging in the Body and Peripheral Vascular System

OBJECTIVE Time-resolved MR angiography (MRA) is a technique designed for fast vascular imaging. The purpose of this article is to introduce the multiple potential uses for time-resolved MRA in the body and peripheral vascular system in the hope that time-resolved MRA will become a more widely used technique. CONCLUSION Time-resolved MRA is a useful technique with many clinical applications.

Simple changes to 1.5-T MRI abdomen and pelvis protocols to optimize results at 3 T.

OBJECTIVE Simply transposing 1.5-T abdominal and pelvic MRI protocols to 3-T scanners does not result in optimized images. Simple modifications can be made to preexisting 1.5-T protocols to obtain image quality at 3 T that is comparable to that at 1.5 T. CONCLUSION We illustrate several simple modifications to 1.5-T body protocols that maintain image quality at 3 T.

Expectoration of a Lung Metastasis in a Patient with Colorectal Carcinoma

Metastatic disease is present in up to 20% of patients at the time of diagnosis of colorectal cancer. The most frequently involved sites are the liver and the lungs. A rare form of lung metastatic disease is endobronchial metastases, most commonly seen with breast cancer and colon cancer. Their clinical and imaging profile is similar to primary bronchogenic carcinoma. Tumor expectoration is an unusual manifestation of endobronchial metastases (as well as of the primary lung carcinoma). We report the case of a 75-year-old man with known liver and lung metastatic disease from colon cancer who experienced an episode of tissue expectoration. Pathology examination of the expectorated piece of tissue was consistent with colonic adenocarcinoma. Tumor expectoration is a rare event, with < 30 cases reported in the literature. Most of the cases reported include secondary lung malignancies, with renal cell carcinoma being the most common primary site. Endobronchial metastases from colon cancer are rare. Patients with colon cancer can benefit from sputum cytology because this type of metastases is shown to have exfoliative properties. To assess the need for endobronchial management with stent placement or bracytherapy, bronchoscopy should be considered in certain circumstances (the onset of respiratory symptoms, rapid response to chemotherapy, long history of metastatic disease with multiple systemic therapies given, undulating response in tumor, as well as after a reported episode of tissue expectoration).

Torsion of a hyperstimulated ovary during pregnancy: a potentially difficult diagnosis

Ovarian torsion in a pregnant infertility patient is an important and difficult diagnosis to make. We present two cases of torsed hyperstimulated ovaries where grey scale and Doppler sonographic evaluation were inconclusive. In one case, magnetic resonance imaging (MRI) was used to make the diagnosis. In the second case, physical findings observed during the ultrasound exam were diagnostic. We think these two cases are good teaching examples of how to approach this difficult diagnosis and emphasize that MRI and physical exam skills are useful adjuncts to ultrasound in the evaluation of a pregnant patient.

Comparison of multidetector computed tomography angiography and cholangiography performed at 80 and 120 kVp in live liver donors.

Objective The objective of this study was to compare the radiation exposure and image quality of contrast-enhanced multidetector computed tomography angiography (CTA) and computed tomography cholangiography (CTC) performed for living liver donor evaluation using 80 and 120 kVp. Methods Ninety-three potential liver donors who underwent preoperative contrast-enhanced 64 multidetector CTA and CTC were retrospectively divided into 2 groups: at 80 and at 120 kVp. An institutional review board waiver was obtained. Signal-to-noise ratio and contrast-to-noise ratio of the hepatic artery and common bile duct were obtained. The dose-length product was recorded. Image quality and visibility of hepatic artery and biliary tract anatomy were evaluated. Mann-Whitney U test was used for statistical evaluation. Results Mean hepatic artery/common bile duct signal-to-noise ratio was 28.9/28.6 (SD, 14.2/10.0) at 80 kVp and 27.6/25.8 (SD, 8.0/6.2) at 120 kVp (P = 0.61/0.099). Mean hepatic artery/common bile duct contrast-to-noise ratio was 24.8/23.3 (SD, 12.9/8.6) at 80 kVp and 22.2/19.3 (SD, 7.7/5.0) at 120 kVp (P = 0.76/0.005). Mean CTA/CTC dose-length product was 279/281 (SD, 42/52) mGy-cm at 80 kVp and 407/451 (SD, 208/243) mGy-cm at 120 kVp (P = 0.026/0.002). Computed tomography cholangiography image quality and visibility of biliary tract anatomy were not significantly different at 80 versus 120 kVp (all P > 0.13). Computed tomography angiography image quality was significantly lower (P < 0.01), and the noise scores significantly higher (P < 0.01) at 80 versus 120 kVp, but diagnostic. Conclusions Contrast-enhanced CTA and CTC performed at 80 kVp result in comparable image quality and anatomical evaluation with reduced radiation exposure when compared with 120 kVp.