background: various variance reduction techniques such as forced detection (fd) have been implemented in monte carlo (mc) simulation of nuclear medicine in an effort to decrease the simulation time while keeping accuracy. however most of these techniques still result in very long mc simulation times for being implemented into routine use. materials and methods: convolution-based forced detectio...

UNLABELLED In patients with gastroenteropancreatic (GEP) neuroendocrine tumors, we investigated the usefulness of somatostatin receptor scintigraphy (SRS) in the detection of liver metastasis, which represents the most important prognostic factor in these tumors, and in the management of affected patients. METHODS We enrolled 149 patients with GEP tumors, 69 during initial staging and 80 in f...

Stimulation-induced changes in transverse relaxation rates can provide important insight into underlying physiological changes in blood oxygenation level-dependent (BOLD) contrast. It is often assumed that BOLD fractional signal change (DeltaS/S) is linearly dependent on echo time (TE). This relationship was evaluated at 9.4 T during visual stimulation in cats with gradient-echo (GE) and spin-e...

PURPOSE Diffusion MRI is compromised by unknown field perturbation during image encoding. The purpose of this study was to address this problem using the recently described approach of concurrent magnetic field monitoring. METHODS Magnetic field dynamics were monitored during the echo planar imaging readout of a common diffusion-weighted MRI sequence using an integrated magnetic field camera ...

BACKGROUND Focused ultrasound (FUS) is entering clinical routine as a treatment option. Currently, no clinically available FUS treatment system features automated respiratory motion compensation. The required quality standards make developing such a system challenging. METHODS A novel FUS treatment system with motion compensation is described, developed with the goal of clinical use. The syst...

OBJECTIVE Resting-state functional MRI (rsfMRI) has been increasingly used for understanding brain functional architecture. To date, most rsfMRI studies have exploited blood oxygenation level-dependent (BOLD) contrast using gradient-echo (GE) echo planar imaging (EPI), which can suffer from image distortion and signal dropout due to magnetic susceptibility and inherent long echo time. In this s...

With improved B 0 homogeneity along with satisfactory gradient performance at high magnetic fields, snapshot gradient-recalled echo-planar imaging (GRE-EPI) would perform at long echo times (TEs) on the order of T2*, which intrinsically allows obtaining strongly T2*-weighted images with embedded substantial anatomical details in ultrashort time. The aim of this study was to investigate the feas...

UNLABELLED The objective of this study was to determine whether posttherapy (131)I SPECT/CT changed the need for additional cross-sectional imaging or modified the American Thyroid Association risk of recurrence classification. We performed planar imaging and SPECT/CT in a consecutive series of patients after (131)I therapy. METHODS Planar imaging and SPECT/CT were performed on 148 consecutiv...

This study examined the effects of varying the predictability of nonrewarding events on behavior and neural activation using a rapid mixed-trial functional magnetic resonance imagery (fMRI) design. Twelve adult subjects were scanned with echo planar imaging during performance of a visual detection task where the probability of events (target and nontarget) varied. This task included expected an...

A new magnetization preparation and image acquisition scheme was developed to obtain high-resolution brain images with optimal tissue contrast. The pulse sequence was derived from an optimization process using simulated annealing, without prior assumptions with regard to the number of radiofrequency (RF) pulses and flip angles. The resulting scheme combined two inversion pulses with the acquisi...