Purpose: In patients with huge leiomyoma and with adenomyosis of the uterus, a peculiar area of hypointensity was occasionally observed on postcontrast magnetic resonance (MR) imaging in the dorsal portion of the enlarged uterus near the sacral promontory. We describe the imaging characteristics of these MR findings and correlate them with histopathological findings to examine whether the areas represent specific pathological changes.
Methods: Ten patients with huge leiomyomas and two with huge adenomyotic lesions whose imaging revealed the hypointensity were enrolled. All had enlarged uteri that extended beyond the sacral promontory. MR findings of the hypointense areas were evaluated and correlated with histopathological findings in 5 patients with leiomyoma and two with adenomyosis who had hysterectomy.
Results: The ten patients with leiomyoma showed flare-shaped hypointensity arising from the dorsal surface of the uterine body that extended deep into the tumor. The base of the hypointense areas was narrow in 5 patients with intramural leiomyoma and broad in five with subserosal leiomyoma. Two patients with adenomyosis showed nodular-shaped areas of hypointensity in front of the sacral promontory. Precontrast T₁- and T₂-weighted MR images showed no signal abnormalities in the portions corresponding to the hypointensity in any of the 12 patients. Pathological examinations showed no specific findings in the portions corresponding to the hypointensity in the 7 patients who had hysterectomy.
Conclusion: The areas of hypointensity may represent functional changes, such as decreased localized blood flow caused by compression of the sacral promontory.

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Purpose: To propose a simple and useful method for correcting nonuniformity of high-field (3 Tesla) T₁-weighted spin-echo (SE) images based on a B1 field map estimated from gradient recalled echo (GRE) signals.
Methods: To estimate B1 inhomogeneity, spoiled gradient recalled echo (SPGR) images were collected using a fixed repetition time of 70 ms, flip angles of 45 and 90 degrees, and echo times of 4.8 and 10.4 ms. Selection of flip angles was based on the observation that the relative intensity changes in SPGR signals were very similar among different tissues at larger flip angles than the Ernst angle. Accordingly, spatial irregularity that was observed on a signal ratio map of the SPGR images acquired with these 2 flip angles was ascribed to inhomogeneity of the B1 field. Dual echo time was used to eliminate T₂^* effects. The ratio map that was acquired was scaled to provide an intensity correction map for SE images. Both phantom and volunteer studies were performed using a 3T magnetic resonance scanner to validate the method.
Results: In the phantom study, the uniformity of the T₁-weighted SE image improved by 23%. Images of human heads also showed practically sufficient improvement in the image uniformity.
Conclusion: The present method improves the image uniformity of high-field T₁-weighted SE images.

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Purpose: We evaluated the automated magnetic resonance spectroscopic (MRS) characteristics of intra- and extraventricular neurocytomas.
Materials and Methods: One extra- and 4 intraventricular neurocytomas were studied. Automated single-voxel proton MRS was performed with a 1.5T MR scanner. The results of 6 total automated MR spectra were analyzed for each tumor.
Results: Lactate resonance was detected as a doublet in 3 MR spectra of 2 intraventricular neurocytomas. A peak corresponding to N-acetylaspartate (NAA) was small in 5 MR spectra of 4 intraventricular neurocytomas. Creatine (Cr) resonance was detected in all 6 MR spectra. Prominent choline (Cho) resonance was found in all 6 MR spectra. The myoinositol (MI) and/or glycine (Gly) peaks were large in 3 MR spectra of 2 intraventricular neurocytomas.
Conclusion: The presence of the NAA signal and high MI and/or Gly signals may be characteristic features of intraventricular neurocytomas. A combination of prominent Cho resonance and detectable Cr resonance is a common feature of both intra- and extraventricular neurocytomas.

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The in vivo measurement of oxygen in tissues is of great interest because of oxygen's fundamental role in life. Many methods have been developed for such measurement, but all have been limited, especially with regard to repeated measurement, degree of invasiveness, and sensitivity. We describe electron spin resonance (ESR) oximetry with paramagnetic oxygen-sensing probe for in vivo measurement of oxygen in brain tissues by home-made ESR/MR dual imaging spectroscopy. Lithium 5, 9, 14, 18, 23, 27, 32, 36-octa-n-butoxy-2,3-naphthlocyanine (LiNc-BuO) radical was employed as the solid oxygen-sensing probe, and we confirmed its ability to report partial pressure of oxygen (pO₂) in brain tissues of live animals under normal and pathological conditions for more than a month. pO₂ measurements could also be made repeatedly on the same animal and at the same location. The implantation site of LiNc-BuO in examined rats was verified by 0.5T magnetic resonance (MR) imaging. Septic-shock rats were used to monitor tissue oxygenation during pathological state. A decline in pO₂ levels from severe hypotension during sepsis was detected, and generation of nitric oxide (NO) in brain tissues was confirmed by NO spin trapping. ESR oximetry using oxygen-sensing probe and NO spin-trapping can be used to monitor pO₂ change and NO production simultaneously and repeatedly at the same site in examined animals.

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Purpose: Pulsed arterial spin labeling (PASL) is a magnetic resonance (MR) method for measuring cerebral blood flow. Although several validation studies for PASL in animals and humans have been reported, no reports have detailed the fundamental study of PASL using a flow phantom. We compared the true and theoretical flow rates in a flow phantom to confirm the analytical validity of quantitative perfusion imaging with Q2TIPS sequence.
Methods: We built a flow phantom consisting of a 40-mm diameter plastic syringe filled with plastic beads and small plastic tubes 4 mm in diameter. Gd-DTPA-doped 8L water solution (0.1 mM) was circulated between the syringe and a tank through a plastic tube by a constant flow pump while the flow rate was adjusted between 0 and 2.61 cm/s. Q2TIPS sequence parameters were TI₁=50 ms and TI₂=1400 ms. Five imaging slices of 50 subtraction images were acquired sequentially in a distal-to-proximal direction using a single-shot echo planar imaging (EPI) technique. The theoretical flow rate calculated based upon the previously reported kinetic model for Q2TIPS was compared with the true flow rate.
Results: A good linear relationship was observed between the theoretical, F′, and true flow rates, F, in a flow rate range of 1.43 to 1.95 cm/s (F′=1.024•F−1.915, R²=0.902). The ratio of theoretical to true flow rate was 92 (+/−) 4%.
Conclusion: Flow rate was quantified with reasonable accuracy when the entire amount of labeled bolus within the phantom could be recovered. Our experiment confirmed the analytical validity of Q2TIPS and suggested that blood flow measurement may be feasible using the Q2TIPS pulse sequence and kinetic model of the PASL equation.

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The author reviewed brain-imaging studies on human handedness reported in major academic journals for the last 12 years, classified them as having anatomical or functional interest, and attempted to determine consensus on findings and limitations among the studies. Present reviews suggest that there have been fewer functional than anatomical examinations into handedness and that findings from those studies have not been necessarily consistent, that participants' degree of handedness has not been consistent between left-handed and right-handed people, and that much more brain-imaging study is anticipated to examine functional and anatomical differences of handedness based on genetic and environmental models.

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We have developed a compact magnetic resonance (MR) imaging scanner with permanent magnet, gradient coil set, and radiofrequency (RF) coils optimized for whole-hand examination for the diagnosis of rheumatoid arthritis (RA). The system weighs about 600 kg, and installation space is 2 m², excluding the shield room. Hand examinations of normal volunteers and patients with RA were performed using a 3D T₁-weighted gradient-echo (GRE) sequence and short T_I inversion recovery 3D fast spin-echo (STIR-3DFSE) sequence, and anatomical structures and various lesions of the hand caused by RA were clearly visualized in a 16-min examination. It was concluded that the system could be used for diagnosis of RA in even a small clinic.

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Solid-pseudopapillary tumor (SPT) of the pancreas is characterized as cystic, necrotic, and hemorrhagic degeneration. In this study, magnetic resonance (MR) findings of 4 cases were reviewed. Patchy or spotty areas of high intensity that suggested hemorrhagic degeneration were constantly detected on fat-suppressed T₁-weighted images. Dynamic contrast-enhanced MR imaging revealed mild and gradual increase of contrast enhancement in solid portions. Multi-contrast MR imaging that included fat-suppressed T₁-weighted imaging and dynamic contrast-enhanced imaging allowed accurate diagnosis of SPT and its differentiation from other tumors.

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