Hürthle cell neoplasm: correlation of gray-scale and power Doppler sonographic findings with gross pathology.

BACKGROUND: To describe gray-scale and power Doppler (PD) sonographic (US) findings of Hürthle cell neoplasms (HCNs) of the thyroid gland, and to determine if there is any correlation between US and gross pathologic features. METHOD: This retrospective study included 30 pathologically proven HCNs in 30 subjects who underwent preoperative gray-scale and PD US examinations. The size, shape, margin, echogenicity, echotexture, presence or absence of cystic change, calcifications and halo sign, and vascularity at PD US were evaluated. RESULT: The longest diameter of HCNs ranged from 12 mm to 63 mm. The shape and margins of the mass were ovoid and smooth, respectively, in all cases. The echogenicity was hypoechoic, isoechoic, hyperechoic, or mixed in 43.3%, 33.3%, 10.0%, and 13.3%, respectively. The echotexture was heterogeneous in 73.3% and homogeneous in 26.7%. Cystic change was present in 56.7% and involved less than 25% of the volume of the mass in 50.0% and 26-50% of the volume in 6.7%. Coarse calcifications were present in 20.0%. Halo sign was present in all cases. The vascularity was combined peri- and intranodular in all cases: predominantly intranodular in 50.0%, predominantly perinodular in 46.7%, and of the "inferno" type in 3.3%. All HCNs were encapsulated on gross pathologic examination. CONCLUSION: Although many of the US features we observed were nonspecific, HCNs tend to have a halo sign and combined peri- and intranodular vascularity on US, which raises the possibility of an association. The US halo sign corresponds to tumor capsule ongross pathologic examination.

Manganese-enhanced auditory tract-tracing MRI with cochlear injection.

Recent studies have demonstrated the use of manganese ion (Mn2+)) as an in vivo neuronal tract tracer. In contrast to histological approaches, manganese tracing can be performed repeatedly on the same living animal. In this study, we describe the neuroaxonal tracing of the auditory pathway in the living guinea pig, relying on the fact that Mn2+ ion enters excitable cells through voltage-gated calcium channels and is an excellent MRI paramagnetic tract-tracing agent. Small focal injections of Mn2+ ion into the cochlea produced significant contrast enhancement along the known neuronal circuitry. This in vivo approach, allowing repeated measures, is expected to open new vistas to study auditory physiology and to provide new insights on in vivo axonal transport and neuronal activity in the central auditory system.

Incidental magnetization transfer effects in multislice brain MRI at 3.0T.

PURPOSE: To evaluate the effect of incidental magnetization transfer (iMT) in multislice brain imaging at 3.0T. MATERIALS AND METHODS: The contribution of iMT to multislice brain MRI was evaluated at 3.0T. In 10 normal subjects we obtained multislice fast spin-echo (FSE) MR images using a 16-echo pulse train without an off-resonance MT pulse at 3.0T and 1.5T. We quantified the extent of iMT by calculating the iMT ratio (iMTR). RESULTS: We found that the iMT contrast (iMTC) has a greater effect at 3.0T. As the number of slices increased in multislice FSE imaging, the difference between two field strengths became larger. Compared to WM structures, however, the difference in iMT effect between 1.5T and 3.0T was smaller in the case of GM structures. CONCLUSION: The iMTC has a greater effect at 3.0T. The strength of the iMT is different for different tissue types and also varies according to the number of slices used.

Evaluation of white matter structures in patients with tinnitus using diffusion tensor imaging.

Recent functional imaging studies have demonstrated that the sensation of tinnitus is associated with activity in cortical regions functionally linked to subserve the generation, perception and processing of the tinnitus stimulus. Previous functional imaging studies have focused primarily on the cortical centers. However, none of these examined the functional nature of associated white matter interconnecting these cortical centers. In this study, we investigate the integrity of white matter tracts interconnecting the auditory system to the parietal and frontal corticies in tinnitus patients using diffusion tensor imaging. Our preliminary results suggest the possible involvement of associated white matter structures in addition to processing cortical centers in tinnitus patients compared with healthy subjects.

Magnetic resonance voiding cystography in the diagnosis of vesicoureteral reflux: comparative study with voiding cystourethrography.

PURPOSE: To evaluate the feasibility of magnetic resonance voiding cystography (MRVC) compared with voiding cystourethrography (VCUG) for detecting and grading vesicoureteral reflux (VUR). MATERIALS AND METHODS: MRVC was performed upon 20 children referred for investigation of reflux. Either coronal T1-weighted spin-echo (SE) or gradient-echo (GE) (fast multiplanar spoiled gradient-echo (FMPSPGR) or turbo fast low-angle-shot (FLASH)) images were obtained before and after transurethral administration of gadolinium solution, and immediately after voiding. The findings of MRVC were compared with those of VCUG and technetium-99m ((99m)Tc) dimercaptosuccinic acid (DMSA) single-photon emission computed tomography (SPECT) performed within 6 months of MRVC. RESULTS: VUR was detected in 23 ureterorenal units (16 VURs by both methods, 5 VURs by VCUG, and 2 VURs by MRVC). With VCUG as the standard of reference, the sensitivity of MRVC was 76.2%; the specificity, 90.0%; the positive predictive value, 88.9%; and the negative predictive value, 78.3%. There was concordance between two methods regarding the grade of reflux in all 16 ureterorenal units with VUR detected by both methods. Of 40 kidneys, MRVC detected findings of renal damage or reflux nephropathy in 13 kidneys, and (99m)Tc DMSA renal SPECT detected findings of reflux nephropathy in 17 kidneys. CONCLUSION: Although MRVC is shown to have less sensitivity for VUR than VCUG, MRVC may represent a method of choice offering a safer nonradiation test that can additionally evaluate the kidneys for changes related to reflux nephropathy.

Auditory neural pathway evaluation on sensorineural hearing loss using diffusion tensor imaging.

Diffusion tensor imaging is a new in vivo tool not only for the assessment of white matter structural integrity but also for diagnosis and assessment of disease conditions which disturb tissue structural coherence. In this study, we investigated the integrity of auditory pathway in patients of sensorineural hearing loss by means of fractional anisotropy of water diffusion to see any subtle changes of auditory pathways resulting from sensorineural hearing loss. In addition, this study suggests that the diffusion anisotropy measured by diffusion tensor imaging is highly sensitive to otherwise subtle disease processes not normally seen with conventional magnetic resonance imaging or computed tomography contrast.