Ultrasound in dermatology: Principles and applications

Ultrasonic imaging has been used in the field of dermatology for nearly 30 years. In this review, we seek to explain the basic principles of ultrasound as they relate to the skin. Based on differences in keratin, collagen, and water content, ultrasonic waves are reflected back to a transducer and translated into a gray-scale image for interpretation. The technicalities of the process and its variations (power, continuous wave Doppler ultrasound, ultrasound elastography) are briefly reviewed, and we further highlight many of the applications for ultrasound in the treatment and diagnosis of dermatologic conditions, including melanoma and nonmelanoma skin cancer, benign tumors, inflammatory diseases, and lipoablation. Each of these entities is uniquely characterized using ultrasonic techniques. Based on published sources, we contend that although ultrasound is still being fine-tuned for application in dermatology and largely remains in experimental phases, it has potential for use in many arenas of our specialty.     

Small hypervascular enhancing lesions on arterial phase images of multiphase dynamic computed tomography in cirrhotic liver: fate and implications

OBJECTIVE: Our purpose was to determine the significance of small hypervascular enhancing lesions exclusively on the arterial phase images of dynamic computed tomography in cirrhotic liver. METHODS: One hundred sixty-nine enhancing lesions (>5 and <30 mm) on the arterial phase images of dynamic computed tomography in 67 patients with cirrhotic liver, not distinguished from background hepatic parenchyma on equilibrium phase images without hypoattenuation density on portal phase images, were subjected to a retrospective assessment in terms of the lesion growth in addition to the location, size, and contour of the lesions, depending on the final diagnoses of the individual lesions. RESULTS: Twenty-eight (17%) of the 169 enhancing lesions were hepatocellular carcinomas (HCCs). All of the 43 wedge-shaped, subcapsular lesions were benign, and 126 nodular or irregular lesions were subcapsularly (benign, n = 59; HCC, n = 11) or centrally (benign, n = 39; HCC, n = 17) located. Significant differences were found between HCCs and benign lesions in terms of their shape (P = 0.002) and location (P = 0.041), and the positive and negative predictive values of centrally located lesions for diagnosing HCCs were 21% and 85%, respectively. The positive and negative predictive values for the diagnosis of HCC based on the lesion growth were 90% and 93%, respectively. CONCLUSIONS: Because of the low positive predictive value of non-wedge-shaped, centrally located, early enhancing lesions in the diagnosis of HCC, the serial follow-up for examining lesion growth is essential to the correct diagnosis of small arterial hypervascular lesions in cirrhotic liver.     

Intrauterine device found in an ovarian carcinoma

Displacement of an intrauterine device (IUD) through the perforation site is a rare but one of the major complications. Theoretically, an extrauterine IUD can be located anywhere in the abdominopelvic cavity. It may be asymptomatic or may cause serious complications, including infection, fistula, organ perforation, or bowel obstruction. However, there is no report of IUD located within an ovarian carcinoma to our knowledge, and our report is the first case of an IUD found in the center of an ovarian cancer.     

Magnetic resonance cholangiography: comparison of two- and three-dimensional sequences for assessment of malignant biliary obstruction

The purpose was to retrospectively compare two-dimensional (2D) magnetic resonance cholangiography (MRC) including breath-hold single-shot rapid acquisition with relaxation enhancement (RARE) and multislice half-Fourier RARE versus navigator-triggered 3D-RARE MRC in the evaluation of biliary malignancy. MRC findings were evaluated in 31 patients with malignant biliary obstruction, including biliary malignancy, gallbladder carcinoma, and ampullary cancer. Two observers independently reviewed the images to assess the overall image quality, artifacts, ductal conspicuity, extent of disease, diagnostic confidence of tumor extent, and origin of tumor. The results were compared with surgical and histopathologic findings. Studies obtained with 3D-MRC were of significantly higher technical quality than those obtained with 2D-MRC. However, the accuracy between two sequences for classification of tumor showed no statistical significance. There was no significant difference between the Az values of 2D- and 3D-MRC for overall tumor extent in bilateral second order branch, intrapancreatic common bile duct (CBD) involvement (Az = 0.889, 0.881 for 2D and Az = 0.903, 0.864 for 3D). Nor was there a significant difference between two sequences in the assessment of the origin of tumor. Although 3D-MRC has superior image quality over 2D-MRC, 3D-MRC showed no statistically significant difference in accuracy compared with 2D-MRC for evaluating the extent of disease in malignant biliary obstructions.     

Double common bile duct: curved-planar reformatted computed tomography (CT) and gadobenate dimeglumine-enhanced MR cholangiography

We present the case of a 61-year-old female with double common bile duct (CBD) with an opening into the lesser curvature of the stomach. We discuss the role of curved-planar reformatted computed tomography (CT) and gadobenate dimeglumine (Gd-BOPTA)-enhanced T1-weighted MRI in confirming the diagnosis of this uncommon disease.     

Small hypervascular hepatocellular carcinomas: value of “washout” on gadolinium-enhanced dynamic MR imaging compared to superparamagnetic iron oxide-enhanced imaging

The aim of this study was to retrospectively compare the value of “washout” on dynamic MR imaging with superparamagnetic iron oxide (SPIO)-enhanced imaging features of small hepatocellular carcinoma (HCC). A total of 74 small (5–30 mm) hypervascular HCCs in 42 cirrhotic patients who underwent double contrast material-enhanced MR imaging were evaluated to determine the presence of washout in the portal or equilibrium phase of gadolinium-enhanced dynamic imaging and decreased uptake of SPIO on T2*-weighted imaging. HCCs were verified histologically (n = 13) or by serial follow-up imaging studies (n = 61). According to the size of the lesions, 27 vs. 73% (<10 mm, n = 15; P = 0.016 on McNemar test), 39 vs. 79% (10–14 mm, n = 28; P = 0.002), 50 vs. 93% (15–20 mm, n = 14; P = 0.031), and 82 vs. 100% (>20 mm, n = 17; P = 0.250) of the lesions showed washout vs. decreased SPIO accumulation respectively. The larger the lesion, the higher the prevalence of washout or decreased SPIO uptake (P = 0.004 or P = 0.036, respectively, on Mantel-Haenszel test). In many small hypervascular HCCs up to 2 cm, SPIO-enhanced MR imaging offers essential information for early diagnosis in the absence of washout on dynamic imaging.     

A case of cerebellar infarction caused by vertebral artery injury from a stab wound to the neck

Vertebral artery injuries are the least common arterial injuries because of the deep location of the vessel in a bony canal. Injury of this vessel has not been associated with neurological deficits, and it is thought that many of these injuries are not recognized. The incidence of vertebral artery injury occurring after a penetration wound to the neck varies from 1.0% in gunshot wounds to 7.4% in stab wounds. However, even with vertebral artery injury in penetration wounds of the neck the association with cerebellar infarction is a rare occurrence. We describe a case of cerebellar infarction caused by vertebral artery injury from a stab wound that severed the vessel between the transverse processes of C3 and C4 with a hypoplastic contralateral vertebral artery. The patient ultimately suffered infarction of the cerebellum due to the lack of preservation of the posterior inferior cerebellar artery blood flow. Management is discussed and the medical literature is reviewed.