Unexpectedly Smaller Artifacts of 3.0-T Magnetic Resonance Imaging than 1.5 T: Recommendation of 3.0-T Scanners for Patients with Magnet-Resistant Adjustable Ventriculoperitoneal Shunt Devices.

BACKGROUND: Magnetic resonance imaging (MRI) artifacts of adjustable shunt devices are thought to be similar to metal clip artifacts, in that they are larger with higher field strength scanners. We have published several reports about the artifacts of new MRI-resistant adjustable shunt devices, and we found a case in which a 3.0-T scanner showed smaller artifacts than the 1.5-T scanner. We aimed to clarify whether this claim is true or not. METHODS: Under permission of our institutional Ethical Committee, 2 volunteers underwent imaging studies using 3.0-T and 1.5-T scanners from GE, Siemens, and Philips. Four MRI-resistant adjustable shunt devices-proGAV2.0 (Miethke), Codman Certas Plus (Johnson & Johnson), Polaris (Sophysa), and Strata MR valve (Medtronic)-were fixed on the left temporal scalp. Routine MRI images, including T1-and T2-weighted imaging, fluid-attenuated inversion recovery, diffusion-weighted imaging (DWI), and magnetic resonance angiography (MRA), were obtained. We also compared artifacts between a 3.0-T scanner and a-1.5 T scanner in 4 patients. RESULTS: The 3.0 T-scanners showed smaller artifacts than the 1.5-T scanners on DWI and MRA images for all shunt devices and scanners. In the other sequences, the results depended on the MRI scanner manufacturer; however, the GE 3.0-T scanner showed smaller artifacts in every sequence. This was also true in the 4 clinical cases. CONCLUSIONS: A 3.0-T scanner is recommended over a 1.5-T scanner for patients with MRI-resistant adjustable shunt devices in the diagnosis of acute ischemic condition or when using GE scanners.

Setting pressure can change the size and shape of MRI artifacts caused by adjustable shunt valves: a study of the 4 newest models.

OBJECTIVE: Adjustable shunt valves that have been developed for the management of hydrocephalus all rely on intrinsically magnetic components, and artifacts with these valves on MRI are thus inevitable. The authors have previously reported that the shapes of shunt artifacts differ under different valve pressures with the proGAV 2.0 valve. In the present study the authors compared the size and shape of artifacts at different pressure settings with 4 new-model shunt valves. METHODS: The authors attached 4 new models of MRI-resistant shunt valve to the temporal scalp of a healthy volunteer: the proGAV 2.0; Codman Certas Plus; Polaris; and Strata MR. They set 3 different scales of pressures for each valve, depending on magnet orientation to the body axis. Artifacts were evaluated and compared among all valves on a 3.0-T GE scanner and 2 valves were also evaluated on a Philips scanner and a Siemens scanner. In-plane artifact sizes were evaluated as the maximum distance of the artifact from the expected scalp. RESULTS: The sizes and shapes of artifacts changed depending on valve pressure for all valves on the 3 different MRI scanners. Artifacts were less prominent on spin echo sequences than on gradient echo sequences. For diffusion-weighted imaging and time-of-flight MR angiography, the authors matched image numbers within the same sequence and compared appearances of artifacts. For all valves, the number of images affected by artifacts and the image number showing the largest artifact differed among valve settings. CONCLUSIONS: Artifacts of all adjustable shunt valves showed gross changes corresponding to pressure setting. Not only the maximum distance of artifacts but also the shape changed significantly. The authors suggest that changing pressure settings offers one of the easiest ways to minimize artifacts on MRI.

[Ruptured aneurysm of a posterior inferior pancreaticoduodenal artery associated with duodenal stenosis after transcatheter arterial embolization].

We describe a 72-year-old man admitted to hospital as an emergency case of epigastric abdominal pain. CT scan visualized massive hemorrhage around the pancreatic head. Computed tomographic angiography showed stenosis at the origin of the celiac artery and a 10 mm aneurysm of the posterior inferior pancreaticoduodenal artery (PIPDA). An emergency angiogram revealed a long aneurysm in the PIPDA. The aneurysm had irregular width and was 75 mm in length. A gastroduodenal artery and the PIPDA were supplied from the superior mesenteric artery. A transcatheter arterial embolization (TAE) was performed. We reviewed 45 cases of pancreaticoduodenal aneurysms after 2000 and cases of the pancreaticoduodenal false aneurysms after 1972. As a result, we inferred that this case without pancreatitis or pancreas surgery was a true aneurysm made by the bloodstream changes caused by the celiac artery stenosis.

High ability to predict the treatment outcome of peginterferon and ribavirin combination therapy based on the reduction in HCV RNA levels at 4 weeks after starting therapy and amino acid substitutions in the hepatitis C virus in patients infected with HCV genotype 1b.

BACKGROUND: The ability to predict the outcome of peginterferon (PEG-IFN) and ribavirin combination therapy based on the reduction in hepatitis C virus (HCV) RNA levels at 4 weeks after starting the therapy and amino acid substitutions in HCV was to be confirmed. METHODS: We measured the reduction in HCV RNA levels at 4 weeks after starting the combination therapy, as well as examining amino acid substitutions at residue 70 in the HCV core and within the interferon sensitivity-determining region (ISDR) of HCV non-structural protein 5A (NS5A), for 101 patients infected with HCV genotype 1b. The ability of these factors to predict a sustained virologic response (SVR) was analyzed. RESULTS: When a 3 log(10) reduction in HCV RNA levels at 4 weeks after starting therapy was set as the cut-off value, an SVR was achieved in 37 of the 46 patients (80.4%) with a ≥3 log(10) decrease and in 4 of the 55 patients (7.3%) with a <3 log(10) decrease. All 4 patients who achieved an SVR despite a <3 log(10) reduction in HCV RNA levels at 4 weeks had an arginine at residue 70 in the HCV core and a non-wild-type sequence for the ISDR of HCV NS5A. CONCLUSION: A ≥3 log(10) reduction in HCV RNA levels at 4 weeks after starting therapy indicates that a patient has a high likelihood of achieving an SVR as a final outcome. Additional information on the amino acid substitutions at residue 70 in the HCV core and within NS5A-ISDR will further increase the ability to predict a clinical response.

Paraplegia caused by intratumoral hemorrhage within thoracic epidural granuloma.

An 84-year-old man presented with a rare case of spinal epidural granuloma with intratumoral hematoma resulting in acute paraplegia. He was admitted to our hospital because of lumbago and hematemesis following a fall 10 days before. Progressive paraparesis occurred 2 days after admission. Neurological examination showed paraplegia and hypesthesia below the T10 level. Thoracic radiography revealed some spondylotic changes of the thoracic vertebrae without osteolytic changes. Sagittal T(1)- and T(2)-weighted magnetic resonance imaging of the thoracic spine demonstrated a hyperintense epidural mass lesion compressing the dorsal portion of the thoracic spinal cord at T10-11 space. Emergency laminectomy was performed, and the epidural encapsulated hematoma and elastic yellowish mass adhered to the dura mater were totally removed. Histological examination of the excised specimens showed a granuloma. Motor weakness improved after surgery, and he could walk with a cane about 3 months after surgery. The minor spinal injury probably caused intratumoral hemorrhage within a previous epidural granuloma, suddenly resulting in the paraplegic symptoms.

Mass spectrometry and photoelectron spectroscopy of o-, m-, and p-terphenyl cluster anions: the effect of molecular shape on molecular assembly and ion core character.

Mass spectrometry and photoelectron spectroscopy of o-, m-, and p-terphenyl cluster anions, (o-TP)n(-) (n = 2-100), (m-TP)n(-) (n = 2-100), and (p-TP)n(-) (n = 1-100), respectively, are conducted to investigate the effect of molecular shape on the molecular aggregation form and the resultant ion core character of the clusters. For (o-TP)n(-) and (m-TP)n(-), neither magic numbers nor discernible isomers are observed throughout the size range. Furthermore, their vertical detachment energies (VDEs) increase up to large n and depend linearly on n(-1/3), implying that they possess a three-dimensional (3D), highly reorganized structure encompassing a monomeric anion core. For (p-TP)n(-), in contrast, prominent magic numbers of n = 5, 7, 10, 12, and 14 are observed, and the VDEs show pronounced irregular shifts below n = 10, while they remain constant above n = 14 (isomer A). These results can be rationalized with two-dimensional (2D) orderings of p-TP molecules and different types of 2D shell closure at n = 7 and 14, the monomeric and multimeric anion core, respectively. Above n = 16, the new feature (isomer B) starts to appear at the higher binding side of isomer A, and it becomes dominant with n, while isomer A gradually disappears for larger sizes. In contrast to isomer A, the VDEs of isomer B continuously increase with the cluster size. This characteristic size evolution suggests that the transition to modified 2D aggregation forms from 2D ones occurs at around n = 20.

Photoelectron spectroscopy of cluster anions of naphthalene and related aromatic hydrocarbons.

The electronic structures and structural morphologies of naphthalene cluster anions, (naphthalene)(n)(-) (n=3-150), and its related aromatic cluster anions, (acenaphthene)(n)(-) (n=4-100) and (azulene)(n)(-) (n=1-100), are studied using anion photoelectron spectroscopy. For (naphthalene)(n) (-) clusters, two isomers coexist over a wide size range: isomers I and II-1 (28 < or = n < or =60) or isomers I and II-2 (n > or = ~60). Their contributions to the photoelectron spectra can be separated using an anion beam hole-burning technique. In contrast, such an isomer coexistence is not observed for (acenaphthene)(n) (-) and (azulene)(n) (-) clusters, where isomer I is exclusively formed throughout the whole size range. The vertical detachment energies (VDEs) of isomer I (7 < or = n < or = 100) in all the anionic clusters depend linearly on n(-13) and their size-dependent energetics are quite similar to one another. On the other hand, the VDEs of isomers II-1 and II-2 produced in (naphthalene)(n)(-) clusters with n > or = approximately 30 remain constant at 0.84 and 0.99 eV, respectively, 0.4-0.6 eV lower than those of isomer I. Based upon the ion source condition dependence and the hole-burning photoelectron spectra experiments for each isomer, the energetics and characteristics of isomers I, II-1, and II-2 are discussed: isomer I is an internalized anion state accompanied by a large change in its cluster geometry after electron attachment, while isomers II-1 and II-2 are crystal-like states with little structural relaxation. The nonappearance of isomers II-1 and II-2 for (acenaphthene)(n)(-) and (azulene)(n)(-) and a comparison with other aromatic cluster anions indicate that a highly anisotropic and symmetric pi-conjugated molecular framework, such as found in the linear oligoacenes, is an essential factor for the formation of the crystal-like ordered forms (isomers II-1 and II-2). On the other hand, lowering the molecular symmetry makes their production unfavorable.

Comprehensive photoelectron spectroscopic study of anionic clusters of anthracene and its alkyl derivatives: electronic structures bridging molecules to bulk.

The evolution of the electronic structure of molecular aggregates is investigated using anion photoelectron (PE) spectroscopy for anionic clusters of anthracene (Ac) and its alkyl derivatives: 1-methylanthracene (1MA), 2-methylanthracene (2MA), 9-methylanthracene (9MA), 9,10-dimethylanthracene (DMA), and 2-tert-butylanthracene (2TBA). For their monomer anions (n=1), electron affinities are confined to the range from 0.47 to 0.59 eV and are well reproduced by density functional theory calculations, showing the isoelectronic character of these molecules. For cluster anions (n=2-100) of Ac and 2MA, two types of isomers I and II coexist over a wide size range: isomers I and II-1 (4< or =n<30) or isomers I and II-2 (n> or = approximately 40 for Ac and n> or = approximately 55 for 2MA). However, for the other alkyl-substituted Ac cluster anions (i.e., 1MA, 9MA, DMA, and 2TBA), only isomer I is exclusively formed, and neither isomer II-1 nor II-2 is observed. The vertical detachment energies (VDEs) of isomer I in all the anionic clusters depend almost linearly on n(-1/3). In contrast, the VDEs of isomers II-1 (n> or =14) and II-2 (n=40-100), appeared only in Ac and 2MA cluster anions, remain constant with n and are approximately 0.5 eV lower than those of isomer I. The PE spectra revealed the characteristics of each isomer: isomer I possesses a monomeric anion core that is gradually embedded into the interior of the cluster with increasing n. On the other hand, isomers II-1 and II-2 possess a multimeric (perhaps tetrameric) anion core, but they differ in the number of layers from which they are made up; monolayer (isomer II-1) and multilayers (isomer II-2) of a two-dimensionally ordered, finite herringbone-type structure, in which electron attachment produces only little geometrical rearrangement. Moreover, the agreement of the constant VDEs of isomer II-2 with the bulk data demonstrates the largely localized nature of the electronic polarization around the excess charge in a crystal-like environment, where about 50 molecules provide a charge stabilization energy comparable to the bulk.

Mass spectrometry and photoelectron spectroscopy of tetracene cluster anions, (tetracene)n- (n = 1-100): evidence for the highly localized nature of polarization in a cluster analogue of oligoacene crystals.

Photoelectron spectroscopy of tetracene cluster anions, (tetracene)n- (n = 1-100), reveals the coexistence of two types of isomers, designated as isomers I and II-1 (n = 10-50) or isomers I and II-2 (n > 60), in a wide size range. The vertical detachment energies (VDEs) of isomer I increase persistently due to polarization and structural relaxation effects, where a monomeric anion core is encompassed with geometrically reorganized neutral molecules. Conversely, a characteristic ion distribution in the mass spectrum of (tetracene)n-ensues from the two-dimensional (2D) herringbone-type ordering of isomer II-1, whose VDEs remain constant at 1.80 eV for n >/= 14. Also, isomer II-2, presumably adopting multilayered structural motifs, exhibits invariable VDEs of 2.0 eV, a manifestation of significant charge screening effects in these isomers. The invariable nature of the VDEs of isomers II-1 and II-2 unambiguously demonstrates a largely localized nature of polarization induced by the excess charge residing in microscopic crystal-like environments. Surprisingly, only 14 tetracene molecules within a 2D herringbone-type layer including an excess charge can provide the charge stabilization energy corresponding to approximately 80% of that of the crystal, and the rest of the energy is provided by polarization of neutral molecules in adjacent layers.

Relationship of stimulation site location within the subthalamic nucleus region to clinical effects on parkinsonian symptoms.

OBJECTIVE: To determine the relationship of the stimulation site in the subthalamic region to the clinical effects on parkinsonian symptoms, the monopolar stimulation of 4 electrode contacts and the resulting effects on parkinsonian symptoms were evaluated. METHODS: Seventeen consecutive patients (3 males and 14 females) were enrolled in the study. The patients were evaluated while in a nonmedicated state, and 10-20 min after switching on the pulse generator the effects of stimulation were assessed using separate-subset Unified Parkinson's Disease Rating Scale scores. RESULTS: The relationship between the site stimulated and the percent improvement was analyzed using polynomial regression. Rigidity (p = 0.0004, R2 = 0.15), akinesia (p = 0.02, R2 = 0.07) and total score (p = 0.009, R2 = 0.089) well fit to second-order polynomial regression and showed the greatest improvement after stimulation at 0-1 mm below the horizontal anterior-posterior commissure (AC-PC) plane. Tremor (p = 0.24, R2 = 0.18) and gait (p = 0.36, R2 = 0.001) had a weak relation to the site stimulated, but stimulation at the sites 0-1 mm below the AC-PC plane also produced greater improvement than stimulation at more ventral or dorsal sites. The percent improvement of the posture (p = 0.92, R2 = 0.002) had no relation to the site stimulated. The dorsal border of the subthalamic nucleus was located 0.6 +/- 1.2 mm (n = 27) below the AC-PC plane and the most effective electrode contact 1.2 +/- 1.3 mm (n = 27) below it. CONCLUSIONS: Stimulation around the dorsal border of the subthalamic nucleus, close to the AC-PC plane, produces greater improvement of parkinsonian symptoms than stimulation at more ventral or dorsal sites.

Coexistence of two different anion states in polyacene nanocluster anions.

Two types of anion states are shown to coexist in nanometer-scale polyacene cluster anions. Naphthalene and anthracene nanoclusters having a single excess electron were produced in the gas-phase. Photoelectron spectra of size-selected cluster anions containing 2 to 100 molecules revealed that rigid "crystal-like" cluster anions emerge, greater than approximately 2 nanometers in size, and coexist with the "disordered" cluster anion in which the surrounding neutral molecules are reorganizing around the charge core. These two anion states appear to be correlated to negative polaronic states formed in the corresponding crystals.

Negative ion photoelectron spectroscopy of acridine molecular anion and its monohydrate.

Negative ion photoelectron spectroscopy was employed to investigate the electronic structure of the acridine molecular anion and its monohydrated anion in the gas phase. Their adiabatic electron affinities were measured to be 0.896+/-0.010 and 1.18+/-0.05 eV, and the low-lying electronic excited states in both neutral acridine and in its monohydrate were revealed. The photoelectron spectra clearly exhibit the presence of low-lying singlet and triplet states having a (pi,pi*) configuration in an uncomplexed acridine molecule. Comparison of the photoelectron spectrum of acridine with that of anthracene shows that photodetachment processes into the excited states of (n,pi*) configuration have little intensity, implying a relatively large intramolecular structural relaxation in the (n,pi*) states.

Coexistence of solvated electrons and solvent valence anions in negatively charged acetonitrile clusters, (CH3CN)-n(n=10-100).

Anion photoelectron spectroscopy of acetonitrile cluster anions, (CH3CN)(-)(n) (n=10-100), successfully demonstrates the competitive coexistence of two different anionic species: a solvated electron and a solvent-bound valence anion. The distinctly different nature of these anions is revealed by hole-burning-type photoelectron spectroscopy and relative photodetachment cross section measurements. This unusual coexistence is attributed to the closely lying nature of their anionic states at just the number of solvent molecules sufficient to almost complete the first solvation layer.