Daniel Thomas Ginat

US Elastography of Breast and Prostate Lesions

Elastography is a technique that maps relative tissue stiffness. Ultrasonographic (US) elastography (sonoelastography) is a novel modality that is the subject of active research for clinical applications, primarily breast and prostate lesion imaging. Breast and prostate tumors generally have biomechanical properties different from those of normal tissues: Tumors are usually stiffer. This phenomenon is responsible for tissue contrast on elastograms. For the prostate gland and breast, the main image acquisition techniques are vibration sonoelastography and compression sonoelastography. The sonoelastographic appearances of several common breast lesions, including fibroadenomas, simple and complex cysts, ductal carcinomas, malignant lymph nodes, and hematomas, are reviewed. In addition, the US elastographic appearances of the normal prostate gland, prostate carcinomas, and benign prostate hyperplasia are illustrated. Potential pitfalls in the interpretation of elastograms, including false-positive and false-negative images, are illustrated. These imaging findings are derived from ongoing research because sonoelastography is not yet accepted for routine clinical use.

Intracranial Lesions with High Signal Intensity on T1-weighted MR Images: Differential Diagnosis

Various substances, including methemoglobin, melanin, lipid, protein, calcium, iron, copper, and manganese, are responsible for the intrinsically high signal intensity observed in intracranial lesions at T1-weighted magnetic resonance (MR) imaging. Many of these substances have physical properties that lead to other specific imaging features as well. For example, lipid-containing lesions frequently produce chemical shift artifact, and some melanin-containing lesions exhibit a combination of high signal intensity on T1-weighted images and low signal intensity on T2-weighted images. The location and extent of a region of abnormal signal hyperintensity may be helpful for identifying rare diseases such as an ectopic posterior pituitary gland near the floor of the third ventricle, bilateral involvement of the dentate and lentiform nuclei in Cockayne syndrome, and involvement of the anterior temporal lobe and cerebellum in neurocutaneous melanosis. In cases in which diagnostically specific T1-weighted imaging features are lacking, findings obtained with other MR pulse sequences and other modalities can help narrow the differential diagnosis: An elevated glutamine or glutamate level at MR spectroscopy is suggestive of hepatic encephalopathy; a popcorn ball-like appearance at T2-weighted imaging, of cavernous malformations; and hyperattenuation at computed tomography, of mineral deposition disease. In many cases, a comparison of imaging features with clinical measures enables a specific diagnosis.

Imaging Features of Solitary Fibrous Tumors

OBJECTIVE The goal of this pictorial essay is to illustrate the multimodality imaging features of pleural and extrapleural solitary fibrous tumors. CONCLUSION Solitary fibrous tumors tend to be well-defined, ovoid, heterogeneously enhancing lesions. MRI characteristically depicts areas of low signal intensity that correspond to dense collagen. The findings of lesion multiplicity and hypermetabolism on PET images should raise the suspicion of malignancy.

Transcatheter Renal Artery Embolization: Clinical Applications and Techniques

Renal artery embolization is a minimally invasive procedure that is increasingly being used for treatment of a wide range of conditions. The main indications for renal artery embolization include (1) prenephrectomy and preradiofrequency ablation infarction of renal tumors, (2) management of renal angiomyolipomas, (3) palliations of unresectable renal malignancy, (4) renal hemorrhage (life-threatening or chronic debilitating hematuria), (5) arteriovenous fistulas, (6) vascular malformations, (7) renal artery aneurysms and pseudoaneurysms, and other less common indications, such as severe hydronephrosis and hypertension. A variety of embolic materials are available, such as metal coils, sclerosants (glue, Onyx, absolute ethanol, lipiodol), and particulate embolic agents (polyvinyl alcohol particles and embospheres). Selection of the appropriate agent depends on the clinical application, technical and clinical endpoints, as well as the pathology lesion(s) targeted. Renal artery embolization can be performed alone or in combination with remodeling techniques, stent-grafting, and balloon- or stent-assisted coiling in more complicated cases. The procedure is generally regarded as safe and effective for diverse applications and is considered as an evolving area in the field of endoluminal therapy.

Imaging Features of Midface Injectable Fillers and Associated Complications

SUMMARY: Injectable fillers are increasingly used for midface augmentation, which can be performed for facial rejuvenation and treatment of HIV facial lipoatrophy. A variety of temporary and permanent filler agents has been developed, including calcium hydroxylapatite, collagen, liquid silicone, polytetrafluoroethylene, hyaluronic acid, poly-l-lactic acid, and polyacrylamide gel. Facial fillers are sometimes encountered on radiologic imaging incidentally and should not be mistaken for pathology. Alternatively, patients with facial fillers may undergo imaging specifically to evaluate associated complications, such as infection, overfilling, migration, foreign-body reaction, and scarring. Therefore, it is important to be familiar with the imaging appearances of the various filler materials and their complications.

Cholecystostomy and Transcholecystic Biliary Access

Percutaneous cholecystostomy represents a minimally invasive procedure for providing gallbladder decompression, often in critically ill patient populations. Indications for this procedure include calculous and acalculous cholecystitis, gallbladder perforation, malignant obstruction, percutaneous biliary stone removal, biliary duct drainage, and diagnostic imaging of the gallbladder and biliary ductal system. In addition, gallbladder access provided by percutaneous cholecystostomy may serve to carry additional procedures, such as cholangiograms, gallstone dissolution, and lithotripsy. Review of prior imaging studies including ultrasound, CT, and hepatobiliary scans are essential to planning the procedure, by helping to determine the access route: transhepatic versus transperitoneal. The transhepatic route is preferred in cases of large ascities, bowel interposition, and offers the advantage of greater catheter stability. On the other hand, the transperitoneal route is preferred in the setting of coagulopathy and liver disease. Initial access is gained via insertion of an 18- to 22-gauge needle, followed by use of the Seldinger technique or trocar system to catheterize the gallbladder. Overall technical success rate for percutaneous cholecystostomy is greater than 95%. Clinical improvement is achieved in 56 to 93% of patients. Complications occur in 3 to 13% of cases and are mainly acute and minor. Major complications such as bile peritonitis, significant hemorrhage, and hemo/pneumothorax affect less than 5% of patients. However, sepsis and reported 30-day mortality rates of up to 25% are usually related to underlying morbidities in critically ill patients. Catheters may be removed once the fistula track has matured.

Endovascular radiofrequency ablation: a novel treatment of venous insufficiency in Klippel-Trenaunay patients.

INTRODUCTION Klippel-Trenaunay Syndrome (KTS) is an uncommon congenital disorder of uncertain etiology that comprises the clinical triad of varicose veins, port wine stain, and bony or soft-tissue hypertrophy. The literature suggests that the deep venous system is often under-developed. We propose that duplex venous ultrasound can effectively demonstrate patent deep venous systems in KTS patients with mild to moderate disease, and that endovascular radiofrequency ablation can be utilized in a safe and appropriate therapeutic manner. METHODS A single center retrospective review of three patients with KTS treated with endovascular radiofrequency ablation of the KT veins and/or great saphenous veins was conducted. Preoperatively, patients underwent both venography and were studied with color flow duplex ultrasound system iU22 with a 7-5 MHz linear array probe (Philips Medical Systems, NA, Bothell, Wash). The anomalous KT veins, great saphenous and saphenous tributaries, and associated incompetent perforators were ablated with radiofrequency catheters (VNUS Medical Technologies, Inc, San Jose, Calif). All the radiofrequency ablations were complimented by ultrasound guided sclerotherapy of the varicose tributaries and when evident, incompetent perforator veins. RESULTS The diagnostic series of duplex ultrasounds performed on our KTS patients has demonstrated contiguous deep venous systems in the effected extremity and effectively recognized the associated anomalous superficial venous systems. Our treatment resulted in successful occlusion of the incompetent veins in all three patients. DISCUSSION The three patients, females aged 39, 19, and 16, presented with port wine stains and many years of leg-swelling and varicose veins that were recalcitrant to conservative treatment measures, including compression stockings and pulsed-dye laser therapy. Venography initially revealed poorly developed deep venous systems. However, venous ultrasound demonstrated patent and competent deep venous systems in all of the affected limbs. Radiofrequency ablations were performed to manage the sequella of venous insufficiency. At short-term follow-up, all patients demonstrated markedly decreased leg pain, edema, and varicose vein bulging. CONCLUSIONS Three KTS patients were successfully treated with radiofrequency ablation of the incompetent great saphenous and/or anomalous superficial veins. Although the deep veins were poorly visualized on venography, they were clearly demonstrated with duplex ultrasound and functioned adequately once the incompetent superficial veins were ablated.

Magnetic resonance imaging of neurosarcoidosis.

Neurosarcoidosis is an uncommon condition with protean manifestations. Magnetic resonance imaging (MRI) is often used in the diagnostic evaluation and follow-up of patients with neurosarcoidosis. Therefore, familiarity with the variety of MRI appearances is important. In this pictorial essay, the range of possible patterns of involvement in neurosarcoidosis are depicted and discussed. These include intracranial and spine leptomeningeal involvement, cortical and cerebral white matter lesions, corpus callosum involvement, sellar and suprasellar involvement, periventricular involvement, cranial nerve involvement, cavernous sinus involvement, hydrocephalus, dural involvement, ischemic lesions, perivascular involvement, orbit lesions, osseous involvement, nerve root involvement, and spinal cord intramedullary involvement. Differential diagnoses for each pattern of involvement of neurosarcoidosis are also provided.

Advances in Computed Tomography Imaging Technology

Computed tomography (CT) is an essential tool in diagnostic imaging for evaluating many clinical conditions. In recent years, there have been several notable advances in CT technology that already have had or are expected to have a significant clinical impact, including extreme multidetector CT, iterative reconstruction algorithms, dual-energy CT, cone-beam CT, portable CT, and phase-contrast CT. These techniques and their clinical applications are reviewed and illustrated in this article. In addition, emerging technologies that address deficiencies in these modalities are discussed.

Dynamic optical imaging of vascular and metabolic reactivity in rheumatoid joints

Dynamic optical imaging is increasingly applied to clinically relevant areas such as brain and cancer imaging. In this approach, some external stimulus is applied and changes in relevant physiological parameters (e.g., oxy- or deoxyhemoglobin concentrations) are determined. The advantage of this approach is that the prestimulus state can be used as a reference or baseline against which the changes can be calibrated. Here we present the first application of this method to the problem of characterizing joint diseases, especially effects of rheumatoid arthritis (RA) in the proximal interphalangeal finger joints. Using a dual-wavelength tomographic imaging system together with previously implemented model-based iterative image reconstruction schemes, we have performed initial dynamic imaging case studies on a limited number of healthy volunteers and patients diagnosed with RA. Focusing on three cases studies, we illustrated our major finds. These studies support our hypothesis that differences in the vascular reactivity exist between affected and unaffected joints.