Subcapsular beaded appearance of the kidney on contrast-enhanced CT: indicative of dilated subcapsular lymphatics?

AIM: To assess the renal subcapsular beaded appearance (RSBA) seen on contrast-enhanced multidetector-row computed tomography (CT). MATERIALS AND METHODS: In total, 2,020 consecutive MDCT examinations with both non-contrast-enhanced and contrast-enhanced procedures were assessed retrospectively to identify interconnecting lobular structures in the renal subcapsular area that created a beaded appearance on contrast-enhanced CT. Positive cases were investigated for CT attenuation on unenhanced CT and were then compared with fat-suppressed heavily T2-weighted magnetic resonance imaging (MRI) and follow-up CT if available. The degree of RSBA occupying the renal periphery was evaluated using a three-grade system (Grade I: <25%, Grade II: 25-75%, Grade III: >75% of surface involvement). Only Grades II and III were defined as a positive RSBA. Possible associated findings such as hypertension, chronic kidney disease (CKD), renal atrophy, and liver cirrhosis were also evaluated. RESULTS: The RSBA was positive in 33 (1.63%) of patients and was more commonly found in patients in their seventies (39.4%) with male predominance (male:female ratio, 7:3; p=0.005). Of 33 positive cases, five showed low CT attenuation predominance, 25 showed iso-attenuation, and three showed high attenuation on unenhanced CT. In five positive cases, T2-weighted MRI showed markedly high signal intensity, suggesting prominent capsular lymphatic structures. The RSBA was associated with hypertension (p=0.001) and CKD (p=0.011). CONCLUSION: The MRI findings suggested that the RSBA probably reflects dilated subcapsular lymphatics. Knowledge of this CT finding is clinically important because it might be misinterpreted as other pathological findings.

Evaluation of the fat plane of the pancreatic groove using multidetector CT.

AIM: To assess the pancreatic groove fat plane in the normal population and compare this with the fat plane in patients with groove pancreatitis or carcinoma using multidetector computed tomography (CT). MATERIAL AND METHODS: The pancreatic groove fat plane was evaluated retrospectively in 460 normal subjects (normal group), and in 25 patients with groove pancreatitis or carcinoma (pathology group) using 5 mm- and 1 mm-thick slices of unenhanced axial multidetector CT images. Two investigators independently assessed the degree of pancreatic groove fat plane visualisation using a four-point scale (grade 1: visualisation of 0-25%, grade 2: 26-50%, grade 3: 51-75%, grade 4: 76-100%). Pancreatic parenchymal condition, age, sex, body mass index, diabetes mellitus, and dyslipidaemia were also evaluated. RESULTS: The interobserver agreement for the visualisation grades was almost perfect (k-value = 0.95). In the normal group, grade 4 visualisation of the pancreatic groove fat plane was more common in those aged >80 years (78.6%) compared with younger age groups. Pancreatic atrophy and fatty infiltration significantly improved fat plane visualisation. In the pathology group, grade 4 visualisation of the pancreatic groove fat plane was not seen in either groove carcinoma or pancreatitis. A cut-off point of ≤50% visualisation of the pancreatic groove fat plane showed 95% sensitivity and 82% specificity for detecting possible abnormalities in older patients (>60 years). The clinical factors investigated were not significantly related to pancreatic groove fat plane visualisation. CONCLUSION: Pancreatic groove fat plane visualisation could be a good predictor for detecting groove abnormalities.

Artery of the Superior Orbital Fissure: An Undescribed Branch from the Pterygopalatine Segment of the Maxillary Artery to the Orbital Apex Connecting with the Anteromedial Branch of the Inferolateral Trunk.

BACKGROUND AND PURPOSE: Some branches of the internal maxillary artery have anastomoses with the inferolateral trunk that are important as intracranial-extracranial collateral pathways and as dangerous anastomoses for transarterial embolization of these branches. We present here an undescribed branch potentially anastomosing with the anteromedial branch of the inferolateral trunk, which is provisionally named the artery of the superior orbital fissure, defined as an arterial branch from the pterygopalatine segment of the maxillary artery to the orbital apex at the superior orbital fissure. MATERIALS AND METHODS: Two neuroradiologists reviewed 3D and MPR images of the external and/or common carotid artery with particular interest paid to the artery of the superior orbital fissure in 54 patients who underwent 3D angiography with a field of view covering the pterygopalatine fossa and the cavernous sinus. The underlying diseases in these patients were 17 parasellar hypervascular lesions (including 13 cavernous sinus dural arteriovenous fistulas and 4 meningiomas), 18 internal carotid artery stenoses/occlusions, and 19 other diseases. RESULTS: The artery of the superior orbital fissure was identified in 20 of 54 patients; it arose at the pterygopalatine segment of the maxillary artery, either singly or from a common trunk with the artery of the foramen rotundum, and ran upward to reach the superior orbital fissure. It anastomosed with the anteromedial branch of the inferolateral trunk at the superior orbital fissure with blood flow toward the cavernous sinus (n = 14) and/or the ophthalmic artery (n = 2). It was more prominent in parasellar hypervascular lesions and internal carotid artery stenoses/occlusions than in other diseases. CONCLUSIONS: The artery of the superior orbital fissure, a remnant of the anastomotic artery, was often identified, especially in patients with parasellar hypervascular lesions.

Carcinoid tumors of the pancreas: dynamic CT and MRI features with pathological correlation.

BACKGROUND: Carcinoid tumor of the pancreas is rare, and there are few reports that described its CT or magnetic resonance imaging (MRI) findings. We describe the characteristic CT and MRI findings in four cases of carcinoid tumor of the pancreas. METHODS: Radiologic and pathologic features were analyzed in four patients. All patients underwent triple-phase dynamic CT and MRI. RESULTS: The tumor size in the four cases ranged 15-20 mm and intratumoral calcification was detected in one case. On triple-phase dynamic CT, the peak enhancement of the tumors was seen at the arterial dominant phase in three cases; the remaining one was at the portal venous phase with prolonged contrast-enhancement effect. The tumors showed low to high signal intensity on T2-weighted images. Dilatation of the main pancreatic ducts (MPDs) distal to the tumors was seen in three cases, in which tumor invasion into the MPDs was pathologically confirmed. Furthermore, the tumors having mild to severe fibrosis pathologically invaded into the peripancreatic lymphatics or nerves. CONCLUSION: It would be characteristic of carcinoid tumor of the pancreas to be well enhanced at the arterial dominant phase on dynamic CT, and to highly invade into the MPDs and the peripancreatic lymphatics or nerves.

Changes in responses of wide dynamic range neurons in the spinal dorsal horn after dorsal root or dorsal root ganglion compression.

STUDY DESIGN: The electrophysiologic responses of wide dynamic range neurons in the spinal dorsal horn by compression of the dorsal root or of the dorsal root ganglion were investigated. OBJECTIVES: This study identified differences between the compression of the dorsal root against the compression of the dorsal root ganglion by examining the responses of wide dynamic range neurons. SUMMARY OF BACKGROUND DATA: The wide dynamic range neurons studied were known to be excited by primary afferent fibers, not only combined A delta and C-nociceptive fibers but also low threshold mechanoreceptive A beta fibers and A delta fibers of down hairs. Thus, the wide dynamic range neurons are classified as nociceptive neurons. METHODS: Extracellular activities of 32 wide dynamic range neurons were recorded from the laminae 4-6 of the seventh lumbar cord in anesthetized cats. A microvessel clip (40 g) was applied to compress the dorsal root or the dorsal root ganglion. RESULTS: Dorsal root compression produced only an initial burst (about 10-40 seconds). Prolonged repetitive firings were rarely maintained. In contrast, dorsal root ganglion compression resulted in a maintained repetitive firing throughout the period of compression. After release of compression of the dorsal root and the dorsal root ganglion, responses to brushing were facilitated, and the low threshold center of the receptive field expanded. CONCLUSIONS: These findings are consistent with the previous report that the radicular pain associated with a herniated intervertebral disc initially results from compression of the dorsal root ganglion.