Amit Pandya

CT Enterography at 80 kVp With Adaptive Statistical Iterative Reconstruction Versus at 120 kVp With Standard Reconstruction: Image Quality, Diagnostic Adequacy, and Dose Reduction

OBJECTIVE The objective of our study was to evaluate the image quality and diagnostic adequacy of the following two CT enterography protocols in patients weighing less than 160 lb (72 kg): 80-kVp imaging with the adaptive statistical iterative reconstruction (ASIR) in comparison with 120-kVp imaging with the filtered back projection reconstruction. MATERIALS AND METHODS We retrospectively reviewed 133 CT enterography examinations of 127 patients weighing less than 160 lb, 64 80-kVp examinations, and 69 120-kVp examinations. Image quality for evaluation of the bowel wall, mesenteric vessels, and hepatic parenchyma and the overall image quality were graded on a scale of 1-5 (1 = poor, 2 = acceptable, 3 = good, 4 = very good, 5 = excellent). Diagnostic accuracy for the detection of inflammatory bowel disease was evaluated. The volume CT dose index (CTDI(vol)) was recorded and effective dose was calculated from scanner-generated dose-length product. RESULTS There was a statistically significant decrease in the mean image quality scores for 80-kVp examinations compared with 120-kVp examinations for evaluation of the bowel wall (3.19 vs 3.70, respectively) and liver (3.12 vs 3.81) and for overall image quality (3.23 vs 3.68), but there was no significant decrease in score for evaluation of the mesenteric vessels (3.63 vs 3.67). None of the 80-kVp examinations was graded as poor, and all were considered to be of acceptable quality. Both techniques had comparable diagnostic accuracy for the detection of inflammatory bowel disease. Interobserver agreement was fair to moderate for qualitative image grading and was substantial for the detection of features of inflammatory bowel disease. The mean CTDI(vol) and effective dose for the 80-kVp examinations were 6.15 mGy and 4.60 mSv, respectively, and for the 120-kVp examinations, 20.79 mGy and 15.81 mSv. CONCLUSION In patients weighing less than 160 lb, CT enterography examinations at 80 kVp with 30% ASIR produce diagnostically acceptable image quality with an average CTDI(vol) of 6.15 mGy and an average effective dose of 4.60 mSv.

Emerging Techniques for Dose Optimization in Abdominal CT

Recent advances in computed tomographic (CT) scanning technique such as automated tube current modulation (ATCM), optimized x-ray tube voltage, and better use of iterative image reconstruction have allowed maintenance of good CT image quality with reduced radiation dose. ATCM varies the tube current during scanning to account for differences in patient attenuation, ensuring a more homogeneous image quality, although selection of the appropriate image quality parameter is essential for achieving optimal dose reduction. Reducing the x-ray tube voltage is best suited for evaluating iodinated structures, since the effective energy of the x-ray beam will be closer to the k-edge of iodine, resulting in a higher attenuation for the iodine. The optimal kilovoltage for a CT study should be chosen on the basis of imaging task and patient habitus. The aim of iterative image reconstruction is to identify factors that contribute to noise on CT images with use of statistical models of noise (statistical iterative reconstruction) and selective removal of noise to improve image quality. The degree of noise suppression achieved with statistical iterative reconstruction can be customized to minimize the effect of altered image quality on CT images. Unlike with statistical iterative reconstruction, model-based iterative reconstruction algorithms model both the statistical noise and the physical acquisition process, allowing CT to be performed with further reduction in radiation dose without an increase in image noise or loss of spatial resolution. Understanding these recently developed scanning techniques is essential for optimization of imaging protocols designed to achieve the desired image quality with a reduced dose.

Technique and diagnostic utility of saline infusion sonohysterography

The introduction of saline infusion sonohysterography has significantly improved sonographic diagnosis of various endometrial pathologies. This procedure entails instillation of warm saline into the uterine cavity transcervically to provide enhanced visualization of the endometrium during transvaginal ultrasound examination. This article reviews the sonohysterography technique and current utility, as well as the spectrum of imaging features of various endometrial pathologies.

Congenital Cystic Lesions of the Head and Neck

This article presents clinical characteristics and radiologic features of congenital cervical cystic masses, among them thyroglossal duct cysts, cystic hygromas, branchial cleft cysts, and the some of the rare congenital cysts, such as thymic and cervical bronchogenic cysts. The imaging options and the value of each for particular masses, as well as present clinical and radiologic images for each, are discussed.

Ultrasound imaging of bowel pathology: technique and keys to diagnosis in the acute abdomen.

OBJECTIVE This article illustrates the normal and pathologic sonographic appearances of bowel, with an emphasis on diagnostic ultrasound techniques. CONCLUSION The current role of ultrasound for adult bowel evaluation is limited in the United States, with CT emerging as the primary modality for evaluation of the acute abdomen. However, mounting concerns regarding diagnostic radiation and health care costs may affect practice patterns and shift utilization back toward sonography, which is widely available and relatively inexpensive.

Imaging in Infections of the Head and Neck

Infections of the head and neck vary in their clinical course and outcome because of the diversity of organs and anatomic compartments involved. Imaging plays a central role in delineating the anatomic extent of the disease process, identifying the infection source, and detecting complications. The utility of imaging to differentiate between a solid phlegmonous mass and an abscess cannot be overemphasized. This review briefly describes and pictorially illustrates the typical imaging findings of some important head and neck infections, such as malignant otitis externa, otomastoiditis bacterial and fungal sinusitis, orbital cellulitis, sialadenitis, cervical lymphadenitis, and deep neck space infections.

Multimodality imaging findings in image-guided biopsy proven splenic littoral cell angioma: series of three cases.

Littoral cell angioma (LCA) is a rare primary splenic vascular tumor arising from the littoral cells that line the splenic sinuses of the red pulp. Definitive diagnosis of this entity depends on histology and immunochemical studies, for which splenectomy is usually performed. We present three image-guided percutaneous core biopsy proven cases of splenic LCA and also discuss imaging features of these rare tumors on CT, MR, and US findings.

Usefulness of the Twinkling Artifact in Identifying Implanted Mesh After Inguinal Hernia Repair

Implanted mesh for inguinal hernia repair is often difficult to visualize with gray scale sonography and may present without the knowledge of the sonographer. We sought to evaluate the utility of the twinkling artifact produced by inguinal mesh to assist in mesh identification.

Sonohysterography: Principles, technique and role in diagnosis of endometrial pathology

Sonohysterography (SHG), which provides enhanced endometrial visualization during standard transvaginal ultrasonography, is a relatively safe procedure for the evaluation of endometrial pathology. It can be used to evaluate patients with abnormal vaginal bleeding or infertility. This modality offers real time imaging of the endometrium without exposure to ionizing radiation. SHG is typically used in patients for whom standard transvaginal ultrasonography does not show the endometrium well, show a potential abnormality for which further imaging is required, or in patients without endometrial pathology defined on routine transvaginal imaging but in whom there is a strong clinical suspicion of an abnormality. This article will discuss the utility of the sonohysterogram in evaluation of various endometrial pathologies. Imaging examples of these pathological entities will be illustrated as well.

Limitations of the 2015 ATA Guidelines for Prediction of Thyroid Cancer: A Review of 1,947 Consecutive Aspirations.

Background The 2015 American Thyroid Association (ATA) guidelines have been proposed to aid in the management of thyroid nodules by determining whether fine needle aspiration is indicated. Objective To determine whether the ATA guidelines contribute to the overdiagnosis of thyroid cancer. Patients and Methods This was a retrospective cohort study of ultrasound-imaged thyroid nodules (n = 1947) consecutively aspirated at a tertiary care center from 1 October 2009 to 22 February 2016. Nodules were retrospectively reviewed, assigned a 2015 ATA morphology, and placed into one of five 2015 ATA categories of risk (ATA-1, <1% risk of malignancy; ATA-2, <3% risk; ATA-3, 5% to 10% risk, ATA-4: 10% to 20% risk; ATA-5, >70% to 90% risk) by a reader who was blinded to cytology. ATA category was compared with cytopathology. The positive predictive value (PPV) of each ATA category was calculated with respect to cancer. Numbers needed to aspirate and Pearson correlations were calculated. Interrater agreement for ATA category across five readers was assessed. Results The PPV for cancer increased by ATA category [category 1 to 5, respectively: 0% (0/14), 2% (4/249), 5% (36/733), 12% (104/850), 28% (28/101)]. The number needed to sample to detect one papillary cancer was 125 (ATA-2), 49 (ATA-3), 13 (ATA-4), and 5 (ATA-5). The overall interrater agreement for ATA score across all five readers was fair (intraclass correlation coefficient 0.460). Conclusions The 2015 ATA guidelines stratify risk for thyroid cancer; however, the stratification system is overly optimistic regarding cancer detection rates for the higher-risk nodules, and there is only fair interrater agreement.