Fundamental Study of Three-dimensional Fast Spin-echo Imaging with Spoiled Equilibrium Pulse.

Three-dimensional fast spin-echo (3D FSE) imaging with variable refocusing flip angle has been recently applied to pre- or post-enhanced T1-weighted imaging. To reduce the acquisition time, this sequence requires higher echo train length (ETL), which potentially causes decreased T1 contrast. Spoiled equilibrium (SpE) pulse consists of a resonant +90° radiofrequency (RF) pulse and is applied at the end of the echo train. This +90° RF pulse brings residual transverse magnetization to the negative longitudinal axis, which makes it possible to increase T1 contrast. The purpose of our present study was to examine factors that influence the effect of spoiled equilibrium pulse and the relationship between T1 contrast improvement and imaging parameters and to understand the characteristics of spoiled equilibrium pulse. Phantom studies were conducted using an magnetic resonance imaging (MRI) phantom made of polyvinyl alcohol gel. To evaluate the effect of spoiled equilibrium pulse with changes in repetition time (TR), ETL, and refocusing flip angle, we measured the signal-to-noise ratio and contrast-to-noise ratio (CNR). The effect of spoiled equilibrium pulse was evaluated by calculating the enhancement rate of CNR. The factors that influence the effect of spoiled equilibrium pulse are TR, ETL, and relaxation time of tissues. Spoiled equilibrium pulse is effective with increasing TR and decreasing ETL. The shorter the T1 value, the better the spoiled equilibrium pulse functions. However, for tissues in which the T1 value is long (>600 ms), at a TR of 600 ms, improvement in T1 contrast by applying spoiled equilibrium pulse cannot be expected.

Resection of lung metastasis from gallbladder carcinoma: immunohistochemistry of RCAS1 and CD8+T cells in primary and metastatic tumors.

Advanced Gallbladder cancer has an extremely poor prognosis. We examined a patient with resectable gallbladder cancer with associated lung metastasis. A 64-year-old female patient, diagnosed with gallbladder cancer and a solitary benign lung tumor by imaging, was subjected to extensive cholecystectomy and extrahepatic bile duct resection. After one year, a follow-up CT indicated enlargement of the lung tumor; video-assisted right middle lobectomy was then performed. The lung tumor was diagnosed as a metastasis derived from the gallbladder cancer by pathology and immunohistochemistry. Expression of RCAS1, an independent unfavorable prognostic indicator in gallbladder cancer, was observed in both the gallbladder and lung tumors. However, infiltration of CD8+T cells was only seen in the lung metastatic tumor. She has remained free of any evidence of recurrence in the 10 months and 4 years after the first surgery. The results that metastasis is solitary and infiltrated by CD8+T cells correspond with the present clinical history.