Anuradha S. Shenoy-Bhangle

Radiation Dose Reduction with Hybrid Iterative Reconstruction for Pediatric CT

PURPOSE To assess image quality and radiation dose reduction with hybrid iterative reconstruction of pediatric chest and abdominal computed tomographic (CT) data compared with conventional filtered back projection (FBP). MATERIALS AND METHODS A total of 234 patients (median age, 12 years; age range, 6 weeks to 18 years) underwent chest and abdominal CT in this institutional review board-approved HIPAA-compliant retrospective study. CT was performed with a hybrid adaptive statistical iterative reconstruction (ASIR)-enabled 64-detector row CT scanner. Scanning protocols were adjusted for clinical indication and patient weight to enable acquisition of reduced-dose CT images in all patients, and tube current was further lowered for ASIR protocols. Weight, age, and sex were recorded, and objective noise was measured in the descending thoracic aorta for chest CT and in the liver for abdominal CT. Of the 234 consecutive patients who underwent ASIR-enabled CT (115 chest and 119 abdominal examinations), 70 patients had undergone prior FBP CT. ASIR and FBP CT studies (29 chest and 41 abdominal studies) in these 70 patients were reviewed for image quality, artifacts, and diagnostic confidence by two pediatric radiologists working independently. Data were analyzed with multiple paired t tests. RESULTS Compared with FBP, ASIR enabled dose reduction of 46.4% (3.7 vs 6.9 mGy) for chest CT and 38.2% (5.0 vs 8.1 mGy) for abdominal CT (P < .0001). Both radiologists deemed image quality of and diagnostic confidence with ASIR and FBP CT images as acceptable, without any artifacts. Despite the lower radiation dose used, ASIR images (chest, 10.7 ± 2.5 [mean ± standard deviation]; abdomen, 11.8 ± 3.4) had substantially less objective noise than did FBP images (chest, 13.3 ± 3.8; abdomen, 13.8 ± 5.2) (P = .001, P =.006, respectively). CONCLUSION Use of a hybrid iterative reconstruction technique, such as ASIR, enables substantial radiation dose reduction for pediatric CT when compared with FBP and maintains image quality and diagnostic confidence.

Radiofrequency ablation of intrahepatic cholangiocarcinoma: feasability, local tumor control, and long-term outcome☆

A retrospective analysis of patients who underwent radiofrequency ablation (RFA) of intrahepatic cholangiocarcinoma (IHCC) was performed. Seven patients with 9 tumors underwent RFA. The mean tumor size was 2.4 cm (range=1.3-3.3 cm). RFA achieved technique effectiveness and local tumor control in 89% (8/9 tumors) of the patients respectively, with a mean overall survival of 38.5 months (range=12-69 months). To conclude, RFA was effective in achieving local tumor control and may offer a therapeutic option for patients with recurrent or primary IHCC.

Pediatric imaging: Current and emerging techniques

Imaging has always been an important component of the clinical evaluation of pediatric patients. Rapid technological advances in imaging are making noninvasive evaluation of a wide range of pediatric diseases possible. Ultrasound and magnetic resonance imaging (MRI) are two imaging modalities that do not involve ionizing radiation and are preferred imaging modalities in the pediatric population. Computed tomography (CT) remains the imaging modality with the highest increase in utilization in children due to its widespread availability and rapid image acquisition. Emerging imaging applications to be discussed include MR urography, voiding urosonography with use of ultrasound contrast agents, CT dose reduction techniques, MR enterography for inflammatory bowel disease, and MR cine airway imaging.

Case records of the Massachusetts General Hospital. Case 18-2014. A 32-Year-old man with a rash, myalgia, and weakness.

Dr. Eli Miloslavsky (Medicine): A 32-year-old man was admitted to this hospital because of a rash, muscle pain, weakness, and respiratory failure. The patient had been well until 10 weeks before admission, when a violaceous rash developed involving the eyelids, elbows, metacarpophalangeal and proximal interphalangeal joints, and knees. One week later, intense generalized muscle pain and weakness developed, including difficulty walking, arising from a squat, and climbing stairs. Two weeks later, examination at another hospital revealed a heliotrope rash (a red-to-purple rash on the eyelids), periungual edema, erythematous papules on the fingertips, and moderate-to-severe weakness of the deltoids, triceps, hip flexors, hamstrings, and quadriceps bilaterally. Muscle bulk and tone, deeptendon reflexes, and the sensory examination were normal. Electrodiagnostic studies of muscle and nerve reportedly showed evidence of a chronic proximal myopathy with inflammatory features. Prednisone, 80 mg daily, was administered, with transient improvement in weakness and a reported decrease in the serum creatine kinase level, from 6700 U per liter to 4200 U per liter. Twenty-six days before admission, the administration of azathioprine, 150 mg per day, was begun because of the patient’s progressive weakness (including difficulty raising his arms) and tenderness on deep palpation of the proximal limbs. Two days later, tests of coagulation and the blood level of total bilirubin were normal; other test results are shown in Table 1. Azathioprine was stopped after 2 days because of a rise in the creatine kinase level, and the patient was admitted to the other hospital. Computed tomography (CT) of the chest and abdomen revealed a small left pleural effusion and anasarca. Magnetic resonance imaging (MRI) performed after the administration of gadolinium reportedly revealed enhancement and edema throughout the major muscle groups of the right thigh. Pathological examination of a biopsy specimen of skeletal muscle reportedly revealed mildly increased variation in fiber size and occasional degenerating fibers, myonecrosis, vascular injury, and fibrosis. Rituximab and a 5-day course of intravenous immunoglobulin were administered. Anemia and hypertension reportedly developed. Red cells (6 units) were transfused and antihypertensive agents were administered. Pathological examination of a biopsy specimen of the bone marrow showed normal trilineage hematopoiesis and no malignant cells. Fever developed, and a possible pulmonary infilCase 18-2014: A 32-Year-Old Man with a Rash, Myalgia, and Weakness

Case 18-2014

Dr. Eli Miloslavsky (Medicine): A 32-year-old man was admitted to this hospital because of a rash, muscle pain, weakness, and respiratory failure. The patient had been well until 10 weeks before admission, when a violaceous rash developed involving the eyelids, elbows, metacarpophalangeal and proximal interphalangeal joints, and knees. One week later, intense generalized muscle pain and weakness developed, including difficulty walking, arising from a squat, and climbing stairs. Two weeks later, examination at another hospital revealed a heliotrope rash (a red-to-purple rash on the eyelids), periungual edema, erythematous papules on the fingertips, and moderate-to-severe weakness of the deltoids, triceps, hip flexors, hamstrings, and quadriceps bilaterally. Muscle bulk and tone, deeptendon reflexes, and the sensory examination were normal. Electrodiagnostic studies of muscle and nerve reportedly showed evidence of a chronic proximal myopathy with inflammatory features. Prednisone, 80 mg daily, was administered, with transient improvement in weakness and a reported decrease in the serum creatine kinase level, from 6700 U per liter to 4200 U per liter. Twenty-six days before admission, the administration of azathioprine, 150 mg per day, was begun because of the patient’s progressive weakness (including difficulty raising his arms) and tenderness on deep palpation of the proximal limbs. Two days later, tests of coagulation and the blood level of total bilirubin were normal; other test results are shown in Table 1. Azathioprine was stopped after 2 days because of a rise in the creatine kinase level, and the patient was admitted to the other hospital. Computed tomography (CT) of the chest and abdomen revealed a small left pleural effusion and anasarca. Magnetic resonance imaging (MRI) performed after the administration of gadolinium reportedly revealed enhancement and edema throughout the major muscle groups of the right thigh. Pathological examination of a biopsy specimen of skeletal muscle reportedly revealed mildly increased variation in fiber size and occasional degenerating fibers, myonecrosis, vascular injury, and fibrosis. Rituximab and a 5-day course of intravenous immunoglobulin were administered. Anemia and hypertension reportedly developed. Red cells (6 units) were transfused and antihypertensive agents were administered. Pathological examination of a biopsy specimen of the bone marrow showed normal trilineage hematopoiesis and no malignant cells. Fever developed, and a possible pulmonary infilCase 18-2014: A 32-Year-Old Man with a Rash, Myalgia, and Weakness

MRI of Placenta Accreta, Placenta Increta, and Placenta Percreta: Pearls and Pitfalls

OBJECTIVE The purpose of this article is to provide a primer for radiologists performing MRI for suspected placenta accreta, illustrating normal and abnormal findings and diagnostic pitfalls. Appropriate examination indications and recommendations for optimizing image acquisition and interpretation are summarized. CONCLUSION MRI increases the accuracy of the workup of high-risk patients and aids in multidisciplinary delivery planning to improve maternal outcome. Reader accuracy and confidence require adherence to examination performance, image interpretation criteria, and awareness of common pitfalls.

Preliminary results: prospective clinical study to assess image-based iterative reconstruction for abdominal computed tomography acquired at 2 radiation dose levels.

Objective The objective of this study was to compare image quality for abdominal computed tomographic (CT) images acquired at 200 and 50 mA s and reconstructed with image-based iterative reconstruction. Materials and Methods In this institutional review board–approved prospective study, 22 patients (mean [SD] age, 64.3 [14.4] years; male-female ratio, 12:10) gave informed consent for acquisition of additional abdominal CT images on 64-slice multi-detector CT (MDCT) (Siemens Definition Flash). Standard-dose images were acquired at 200 quality reference mA s, whereas low-dose images were acquired at 50 mA s (all series: 120 kV; 5-mm section thickness; pitch, 0.9:1). The low-dose images were reconstructed with a nonlinear 3-dimensional iterative image reconstruction (3D-IIR) (SafeCT; MedicVision, Tirat Carmel, Israel) (4 settings, namely, A1, A2, A3, and A4) and were assessed by 3 abdominal radiologists for lesion detection, image noise, and visibility of small structures. CATPHAN 500 was scanned at the respective doses to obtain noise spectral density and modulation transfer function. Results Subjective image noise was unacceptable at 50-mA s filtered back projection and improved to average in 50-mA s A1 and minimal or no noise in 50-mA s A4. However, the visibility of small structures was similar to standard-dose filtered back projection images on 50-mA s A2. Objective image noise was reduced to 66% for the 50-mA s 3D-IIR images (9.08 [2.3]/26.75 [6.8]). The modulation transfer function curve demonstrated resolution improvement in the low-dose images with the 3D-IIR technique, whereas the noise spectral density curve confirmed noise suppression in the 50-mA s 3D-IIR images. Conclusions Three-dimensional iterative image reconstruction helps to lower image noise without affecting the visibility of small structures at “moderate” settings. Diagnostically acceptable abdominal CT examinations can be acquired at 75% lower-radiation dose with the help of the image-based iterative reconstruction technique.

Use of fibrinolytics in abdominal and pleural collections.

Fluid collections that are incompletely drained despite adequate catheter position, size, and number represent a minority of abscesses but a source of great frustration for patients, surgeons, and interventional radiologists. Drainage of such complex collections is known to be more effective with the adjunctive use of intracavitary fibrinolytic agents instilled via the drainage catheter. In this review article, we discuss the role of fibrinolytics specifically tissue plasminogen activator as explored by interventional radiologists in enhancing effective drainage of these complex abdominal and pelvic collections as well as complex pleural collections.

Diffusion weighted magnetic resonance imaging of liver: Principles, clinical applications and recent updates

Diffusion-weighted imaging (DWI), a functional imaging technique exploiting the Brownian motion of water molecules, is increasingly shown to have value in various oncological and non-oncological applications. Factors such as the ease of acquisition and ability to obtain functional information in the absence of intravenous contrast, especially in patients with abnormal renal function, have contributed to the growing interest in exploring clinical applications of DWI. In the liver, DWI demonstrates a gamut of clinical applications ranging from detecting focal liver lesions to monitoring response in patients undergoing serial follow-up after loco-regional and systemic therapies. DWI is also being applied in the evaluation of diffuse liver diseases such as non-alcoholic fatty liver disease, hepatic fibrosis and cirrhosis. In this review, we intend to review the basic principles, technique, current clinical applications and future trends of DW-MRI in the liver.

Feasibility and effectiveness of image-guided percutaneous biopsy of the urinary bladder

PurposeTo evaluate the indications, technique, results, and complications of image-guided percutaneous biopsy of the urinary bladder. MethodsThis retrospective study included 15 patients (10 male, 5 female) who underwent image-guided percutaneous biopsy of the urinary bladder between January 1999 and December 2013. The medical records, imaging studies, procedural details, and long-term follow-up of each patient were reviewed in detail to assess the feasibility of percutaneous bladder biopsy.Results Ten patients had focal bladder masses and 5 patients had asymmetric or diffuse bladder wall thickening. Eleven patients had either negative or unsatisfactory cystoscopies prior to the biopsy. Percutaneous biopsies were performed under computed tomography guidance in 12 patients and ultrasound in 3 patients. All procedures were technically successful and there were no procedural complications. Malignancy was confirmed in 8 patients, among whom 6 had transitional cell carcinoma, 1 cervical cancer, and 1 prostate cancer metastasis. Seven patients had a benign diagnosis, including 3 that were later confirmed by pathology following surgery and 2 patients with a false-negative result. The overall sensitivity was 80% and accuracy was 87%.ConclusionsImage-guided percutaneous biopsy of the urinary bladder is a safe and technically feasible procedure with a high sensitivity and accuracy rate. Although image-guided bladder biopsy is an uncommon procedure, it should be considered in selected cases when more traditional methods of tissue sampling are either not possible or fail to identify abnormalities detected by cross-sectional imaging.