What and where information in the caudate tail guides saccades to visual objects

We understand the world by making saccadic eye movements to various objects. However, it is unclear how a saccade can be aimed at a particular object, because two kinds of visual information, what the object is and where it is, are processed separately in the dorsal and ventral visual cortical pathways. Here, we provide evidence suggesting that a basal ganglia circuit through the tail of the monkey caudate nucleus (CDt) guides such object-directed saccades. First, many CDt neurons responded to visual objects depending on where and what the objects were. Second, electrical stimulation in the CDt induced saccades whose directions matched the preferred directions of neurons at the stimulation site. Third, many CDt neurons increased their activity before saccades directed to the preferred objects and directions of the neurons in a free-viewing condition. Our results suggest that CDt neurons receive both "what" and "where" information and guide saccades to visual objects.     

Aliasing artifacts with the BLADE technique: causes and effective suppression

Purpose:

To elucidate the causes of aliasing artifacts with the BLADE technique and clarify the effective suppression methods.

Materials and Methods:

We separately observed the aliasing artifacts of BLADE from features inside and then outside the defined field‐of‐view (FOV) using phantom studies. The effectiveness of suppressing them with phase oversampling (POS) and presaturation pulses (SAT) was evaluated. Finally, our observations were confirmed for a healthy volunteer.

Results:

Characteristic aliasing artifacts were observed from both inside and outside the FOV. Those from inside the FOV were sufficiently suppressed by using a POS of 25%, considering the acquisition time prolongation. Those from outside the FOV were nearly suppressed using SAT outside the FOV without selecting needless receiver coils. Aliasing artifacts on the coronal images of the head and neck with a healthy volunteer were completely suppressed by a combination of using a POS of 25% and using SAT on all four sides outside the FOV.

Conclusion:

The characteristic aliasing artifacts of BLADE are caused from both inside and outside the defined FOV. They can be effectively suppressed by a combination of using a POS of 25% and using SAT on all four sides outside the FOV. J. Magn. Reson. Imaging 2011;33:432–440. © 2011 Wiley‐Liss, Inc.     

Balloon occlusion retrograde transvenous obliteration for inferior mesenteric vein-systemic shunt

Two cases of portosystemic encephalopathy caused by an inferior mesenteric vein (IMV)-internal iliac vein shunt and an IMV-renal vein shunt are presented. IMV and systemic varicosity consisted of a first functional segment, a stagnant segment, and a second functional segment. Both patients underwent balloon occlusion retrograde transvenous obliteration (BRTO), using a microcatheter, to occlude the stagnant segment selectively. Although transient portal vein thrombosis was observed in case 1 and aggravation of esophageal varices was observed in case 2, these complications were tolerable. Following BRTO, the portosystemic encephalopathy in both cases resolved, and serum ammonia levels, although elevated, remained within the normal range.     

Perfusion fraction of diffusion-weighted MRI for predicting the presence of blood supply in ovarian masses

Purpose:

To evaluate whether perfusion fraction (PF) calculated with diffusion‐weighted magnetic resonance imaging (MRI) predicts the presence of blood supply in ovarian masses.

Materials and Methods:

PFs of 92 ovarian lesions in 53 patients administered gadolinium were retrospectively calculated with diffusion‐weighted images at b‐values of 0, 500, and 1000 sec/mm². PFs were compared between ovarian lesions, except for fat, with (n = 21) or without contrast enhancement (n = 57), using Student's t‐test and receiver operating characteristics (ROC) curve analysis. Lesion enhancement rates of contrast‐enhanced images at 30 and 180 seconds after gadolinium injection (ER_30sec and ER_180sec) and PFs were compared using Pearson's correlation coefficient.

Results:

PFs of the lesions with contrast enhancement were significantly higher than those without contrast enhancement (0.22 ± 0.09 and 0.02 ± 0.08, respectively, P < 0.0001). The ROC curve identified the best cutoff point for PF at 0.135 (95.2% sensitivity and 94.7% specificity) as a predictor of the contrast enhancement effect. The area under the ROC curve was 0.984. PF correlated moderately with ER_30sec (0.62, y = 0.13x + 0.04, P < 0.0001) and ER_180sec (0.74, y = 0.13x + 0.03, P < 0.0001).

Conclusion:

PF calculated with diffusion‐weighted images can potentially predict blood supply in ovarian masses. J. Magn. Reson. Imaging 2011. © 2011 Wiley Periodicals, Inc.     

Primary retroperitoneal carcinoid tumor associated with multiple endcrine neoplasia (men) type 1: a case report

We report an extremely rare case of a 69-year-old man having a retroperitoneal carcinoid tumor associated with multiple endocrine neoplasia (MEN) type 1. The patient whose son and daughter were previously diagnosed with MEN type 1 was admitted to the Department of Endocrinology at our hospital for evaluation of this disorder. Computed tomography (CT) and ultrasonography revealed a parathyroid and retroperitoneal tumor (43 mm x 34 mm). The patient did not consent to surgical management of the tumor; however three years later, a follow-up CT revealed tumor enlargement (55 mm x 50 mm). We were unable to rule out a malignancy, and subsequently resected the tumor. A pathological diagnosis of retroperitoneal carcinoid was made. No local recurrence or metastasis have been observed for 21 months.