Transfer of orbital angular momentum of light to plasmonic excitations in metamaterials.

The emergence of the vortex beam with orbital angular momentum (OAM) has provided intriguing possibilities to induce optical transitions beyond the framework of the electric dipole interaction. The uniqueness stems from the OAM transfer from light to material, as demonstrated in electronic transitions in atomic systems. In this study, we report on the OAM transfer to electrons in solid-state systems, which has been elusive to date. Using metamaterials (periodically textured metallic disks), we show that multipolar modes of the surface electromagnetic excitations (so-called spoof localized surface plasmons) are selectively induced by the terahertz vortex beam. Our results reveal selection rules governed by the conservation of the total angular momentum, which is confirmed by numerical simulations. The efficient transfer of light's OAM to elementary excitations in solid-state systems at room temperature opens up new possibilities of OAM manipulation.

Influence of cycloplegia with topical cyclopentolate on higher-order aberrations in myopic children.

PURPOSE: To investigate the influence of cycloplegia with topical cyclopentolate on wavefront aberrations in myopic children. DESIGN: This is a prospective, comparative study. METHODS: Twenty-eight myopic children with a mean age of 7.25 ± 2.55 were enrolled in this study. We evaluated refraction and wavefront aberrations before and after cycloplegia with 1% cyclopentolate hydrochloride. Ocular and corneal aberrations were simultaneously measured and compared with each other. Individual Zernike components were also analyzed up to the sixth order. All these parameters were compared before and after cycloplegia. RESULTS: Ocular higher-order aberrations (HOAs) significantly increased after cycloplegia (P=0.012 for spherical-like and P=0.015 for total HOAs). Corneal HOAs did not change after cycloplegia. When corneal and ocular HOAs were compared, the ocular HOAs were significantly smaller than the corneal HOAs in spherical-like aberrations (P<0.001) and total HOAs (P=0.006). As for individual Zernike components, ocular aberration generally showed smaller or equivalent values in comparison with corneal aberration. In addition, each Zernike component showed a large standard deviation. CONCLUSIONS: Internal optics compensates for corneal HOAs in myopic children, and paralysis of tonic accommodation with cyclopentolate considerably affects ocular HOAs. However, inter-individual variation in each Zernike component is quite large in myopic children.

Intraoperative fluorescence vascular imaging using indocyanine green for assessment of transplanted kidney perfusion.

INTRODUCTION AND OBJECTIVE: Indocyanine green (ICG) emits infrared light with exposure to laser light. When intravenously injected, it binds to plasma proteins and predominantly persists in the vasculature, which is very useful for definition of the vascular network. The HyperEye Medical System (HEMS; Mizuho Ikakogyo Co., LTD, Tokyo, Japan) is a new device able to identify both near-infrared and visible rays "in situ" without needing to dim the operation room lighting. We speculated that intraoperative ICG imaging would be applicable for kidney transplantation, by providing "in situ" determination of successful vascular anastomosis. MATERIALS AND METHODS: Four patients underwent intraoperative ICG imaging following intravenous administration of 1 mL of a solution containing 0.25% ICG. After performing vascular anastomosis, the allograft was examined using the HEMS light source device. Fluorescent signals were transmitted to a digital video processor connected to a television monitor and evaluated in real time. RESULTS: In all 4 patients, intraoperative ICG imaging provided excellent resolution of blood flow at each step in real time, namely, coming from the recipient's artery to the allograft renal artery, circulating throughout the whole grafted kidney, and draining through the allograft renal vein to the recipient's vein. HEMS provides ICG fluorescence image in color, allowing surgeons to clearly discriminate the positional relationship between the target tissue and the surrounding tissue. No complications associated with ICG injection were noted. CONCLUSION: Our preliminary results indicate that HEMS is a feasible and safe ICG imaging system that helps prevent technical failure during vascular anastomosis, and also demonstrates blood supply to the grafted kidney.

Time course of changes in ocular wavefront aberration after administration of eye ointment.

PURPOSE: To investigate the influence of an eye ointment on ocular aberration. DESIGN: Prospective, comparative study. METHODS: In 10 normal volunteers, ocular aberration was assessed before and 5, 30 min, 1, 2, 3, 6, and 12 h after administration of ofloxacin eye ointment. Ocular aberration was sequentially measured over a period of 10 s, and the root mean square (RMS) of the second-, third-, fourth-, and total higher-order aberrations (HOAs) were determined. From the sequential changes in total HOAs during 10 s, the fluctuation index (FI) and stability index (SI) were calculated. The obtained data were compared with those of another 17 normal volunteers who received timolol maleate gel-forming ophthalmic solution. RESULTS: No significant changes in second-order RMS were observed after administration of the ointment. HOAs such as third-, fourth-, and total higher-order RMS significantly changed during the study period (P<0.05, repeated-measures analysis of variance). The RMS of each HOA component significantly increased 5 min after administration compared with the baseline values (P<0.05, Dunnett test). FI also increased significantly 5 min after administration (P<0.05), but SI did not change significantly. When compared with the results of the gel-forming solution group, HOAs and FI showed significantly higher values at several time points during 6 h after application (P<0.05, Mann-Whitney U-test). CONCLUSIONS: Administration of eye ointment significantly degrades optical quality of the eye by increasing and oscillating HOAs. These changes were more pronounced than those after instillation of gel-forming ophthalmic solution for at least several hours.

Vision-related quality of life and visual function in patients undergoing vitrectomy, gas tamponade and cataract surgery for macular hole.

AIM: To evaluate the relationship between vision-related quality of life (VR-QOL) and visual function in patients undergoing vitrectomy, gas tamponade and cataract surgery for macular hole (MH). METHODS: The 25-item National Eye Institute Visual Function Questionnaire (VFQ-25) was self-administered by 32 patients with MH (age 66.2 (SD 5.4) years) preoperatively and at 3 months postoperatively. Clinical data were collected, including logarithm of minimum angle of resolution (logMAR) best corrected visual acuity (BCVA), severity of metamorphopsia and letter contrast sensitivity. The severity of metamorphopsia was evaluated by the M-Charts. MH index was measured using optical coherence tomography. The presence and severity of cataract were graded using the Lens Opacities Classification System III reference standards. Multiple regression analysis was performed to investigate the relationship between various explanatory variables and VFQ-25 questionnaire scores. Explanatory variables tested were the severity of metamorphopsia, visual acuity, letter contrast sensitivity, MH index and grade of cataract. RESULTS: Vitrectomy for MH significantly improved VFQ-25 composite score as well as subscale scores, including general vision, near activities, distance activities, social functioning, mental health and dependency (p<0.05, Wilcoxon signed-rank test). Multiple regression analysis revealed that, both preoperatively and postoperatively, the severity of metamorphopsia had a significant correlation with VFQ-25 composite score (p<0.05), whereas other explanatory variables did not. In addition, changes in the severity of metamorphopsia was the single variable that was significantly related to changes in VFQ-25 composite score (p<0.01). CONCLUSION: Vitrectomy for MH significantly improved VR-QOL. The severity of metamorphopsia was significantly associated with both preoperative and postoperative VR-QOL.

Recovery of corneal irregular astigmatism, ocular higher-order aberrations, and contrast sensitivity after discontinuation of overnight orthokeratology.

AIMS: To examine prospectively the recovery of various parameters after discontinuation of overnight orthokeratology. METHODS: Seventeen subjects undergoing orthokeratology for 12 months were examined. Refraction, corneal topography, wavefront aberrometry, a visual acuity test and a contrast sensitivity test were performed at baseline, 12 months after commencement of the procedure, and 1 week and 1 month after discontinuation of the treatment. Asymmetry and higher-order irregularity components were calculated using a Fourier analysis of the corneal topography data. Contrast sensitivity was assessed at four spatial frequencies, and the area under the log contrast sensitivity function (AULCSF) was calculated. RESULTS: Orthokeratology significantly reduced manifest refraction (p<0.0001, Dunnett test) and significantly improved uncorrected visual acuity (UCVA) at 12 months after commencement of the procedure (p<0.0001). Asymmetry and higher-order irregularity components increased significantly (p<0.0001, p = 0.0032, respectively), and third- and fourth-order aberrations also increased significantly (p<0.0001). The treatment resulted in significant decreases in AULCSF (p = 0.0004). After discontinuing lens wear, all parameters, such as refraction, UCVA, asymmetry, higher-order irregularity, third-order aberration, fourth-order aberration and AULCSF, returned to the baseline level at 1 week. CONCLUSION: This study confirmed that the effect of orthokeratology is completely reversible in light of optical quality of the eye and quality of vision as well as refraction and visual acuity.

Changes in higher-order aberrations after scleral buckling surgery for rhegmatogenous retinal detachment.

PURPOSE: To evaluate changes in higher-order aberrations (HOAs) after scleral buckling surgery for the treatment of rhegmatogenous retinal detachment (RD). DESIGN: Prospective observational comparative case series. PARTICIPANTS: The study included 67 eyes of 67 rhegmatogenous RD patients undergoing scleral buckling surgery, and the fellow normal eyes comprised the control group. Twenty-seven eyes were treated with the segmental buckling procedure and 40 eyes received the encircling buckling procedure alone. METHODS: Hartmann-Shack wavefront analysis was performed at 2 weeks, 1 month, and 3 months postoperatively. MAIN OUTCOME MEASURE: Time course of changes in HOAs. RESULTS: Scleral buckling surgery significantly increased HOAs at 2 weeks (P<0.0001), 1 month (P<0.0005), and 3 months (P<0.05) postoperatively as compared with the control group. At 3 months postoperatively, the HOAs were significantly lower in the encircling group than in the segmental buckling group (P<0.05). The vertical coma (Zernike Z(3)(-1)) became negative (significantly lower than zero, P<0.01) in patients who received segmental buckling in the upper quadrant. The ocular HOAs and logarithm of the minimum angle of resolution best-corrected visual acuity significantly correlated at 3 months postoperatively (third-order root mean square [RMS]: r = 0.445, P<0.0005; fourth-order RMS: r = 0.489, P<0.0001). CONCLUSIONS: Scleral buckling surgery significantly increased HOAs. The segmental buckling procedure increased the HOAs to a greater extent and for a longer duration than the encircling procedure. The direction of coma aberration corresponded to the location of the segmental buckle. The increase in HOAs can be one of the factors responsible for visual disturbances after scleral buckling surgery.

Changes in corneal topography after 25-gauge transconjunctival sutureless vitrectomy versus after 20-gauge standard vitrectomy.

PURPOSE: To evaluate the changes in regular and irregular corneal astigmatism after 25-gauge transconjunctival sutureless vitrectomy and 20-gauge standard vitrectomy. DESIGN: Prospective observational comparative case series. PARTICIPANTS: Thirty-two eyes of 32 patients undergoing 25-gauge transconjunctival sutureless vitrectomy and 25 eyes of 24 patients undergoing 20-gauge standard vitrectomy. METHODS: Corneal topography was obtained preoperatively and at 2 weeks and 1 month postoperatively. MAIN OUTCOME MEASURES: The dioptric data of the central 3-mm zone of the cornea were decomposed using Fourier harmonic analysis into spherical power, regular astigmatism, asymmetry, and higher-order irregularity. RESULTS: None of the 4 Fourier indices changed throughout the observation period in the 25-gauge group. In the 20-gauge group, regular astigmatism, asymmetry, and higher-order irregularity were increased significantly at 2 weeks after vitrectomy (P<0.05, Wilcoxon signed-ranks test) and returned to preoperative levels by 1 month. The spherical power in the 20-gauge group did not change after surgery. For regular astigmatism, asymmetry, and higher-order irregularity, the 20-gauge group showed significantly greater surgically induced changes than the 25-gauge group (P<0.05, Mann-Whitney U test). CONCLUSIONS: Twenty-five-gauge transconjunctival sutureless vitrectomy does not induce significant changes in corneal topography and exerts little influence on the optical quality of the cornea.

Neural correlates of regional EEG power change.

To clarify the physiological significance of task-related change of the regional electroencephalogram (EEG) rhythm, we quantitatively evaluated the correlation between regional cerebral blood flow (rCBF) and EEG power. Eight subjects underwent H2 15O positron emission tomography scans simultaneously with EEG recording during the following tasks: rest condition with eyes closed and open, self-paced movements of the right and left thumb and right ankle. EEG signals were recorded from the occipital and bilateral sensorimotor areas. Cortical activation associated with EEG rhythm generation was studied by the correlation between rCBF and EEG power. There were significant negative correlations between the sensorimotor EEG rhythm at 10-20 Hz on each side and the ipsilateral sensorimotor rCBF and between the occipital EEG rhythm at 10-20 Hz and the occipital rCBF. The occipital EEG rhythm showed a positive correlation with the bilateral medial prefrontal rCBF, while the right sensorimotor EEG rhythm showed a positive correlation with the left prefrontal rCBF. In conclusion, decrease in the regional EEG rhythm at 10-20 Hz might represent the neuronal activation of the cortex underlying the electrodes, at least for the visual and sensorimotor areas. The neural network including the prefrontal cortex could play an important role to generate the EEG rhythm.

Investigation of new cytogenetic biomarkers specific to high-LET radiation using in vivo and in vitro exposed human lymphocytes.

PURPOSE: To find detectable cytogenetic biomarkers that can offer information about the radiation quality of in vivo exposure retrospectively. MATERIALS AND METHODS: Chromosome-type aberrations of peripheral lymphocytes of uterine cancer patients that received internal gamma- and external X-ray therapy or carbon beam therapy and of victims severely exposed to neutrons and gamma-rays in a criticality accident that occurred in Tokai-mura, Japan were analysed. Data obtained from in vitro irradiation experiments using 60Co gamma-rays and 10 MeV neutrons were compared with the in vivo exposure data. RESULTS: The ratio of acentric rings to dicentric chromosomes (termed RaD ratio) and that of excess fragments to dicentrics (termed EfD ratio) showed significant (p < 0.05) differences between the two groups of cancer patients, and these ratios for accidental victims were in between the values of the two groups of cancer patients. The in vitro studies using doses equivalent to 1 - 3 Gy of gamma-rays have confirmed that the EfD ratios were increased with the high LET (linear energy transfer) and RaD ratios decreased. CONCLUSION: The present data show that the RaD and EfD ratios can be used as cytogenetic biomarkers of exposure to high-LET radiation at least within a few years of exposure.

Retention and removal of a new viscous dispersive ophthalmic viscosurgical device during cataract surgery in animal eyes.

AIMS: To assess the retention and removal properties of a new viscous dispersive ophthalmic viscosurgical device (OVD), DisCoVisc, in comparison with those of cohesive (Provisc), dispersive (Viscoat), and viscoadaptive (Healon5) OVDs. METHODS: In 20 porcine eyes, cataract surgery was simulated using one of the four OVDs which were stained with fluorescein for better visualisation. Three parameters were measured. Firstly, the presence/absence of OVDs in the chamber at the completion of phacoemulsification was recorded. Secondly, the time until the OVDs were completely removed from the anterior chamber using the phaco needle was measured. Thirdly, after intraocular lens (IOL) implantation, the time needed to completely remove the OVDs from the chamber with irrigation/aspiration tip was recorded. RESULTS: At the completion of phacoemulsification, the OVDs retained in 0% (0/5) for Provisc, 80% (4/5) for Healon5, 100% (5/5) for DisCoVisc, and 100% (5/5) for Viscoat. The retention of OVDs during phacoemulsification was greatest with Viscoat followed by, in descending order, DisCoVisc, Healon5, and Provisc. The removal of OVDs after IOL implantation took longest with Viscoat followed by Healon5, DisCoVisc, and Provisc. CONCLUSION: The viscous dispersive DisCoVisc showed excellent retention during phacoemulsification, while its removal after IOL implantation was very easy. When compared with the viscoadaptive Healon5, DisCoVisc was retained better in the chamber and was easier to remove. These features of DisCoVisc should be highly advantageous when considering covering the entire cataract surgery procedure with a single OVD.

A new method using F-waves to measure muscle fiber conduction velocity (MFCV).

OBJECTIVE: First, to propose a new technique for measuring muscle fiber conduction velocity (MFCV). Second, to ascertain the validation of the new method that uses F-waves (F-MFCV) in healthy volunteers. Third, to examine the relationship between F-MFCV and motor nerve conduction velocity (MCV) in the same subjects. SUBJECTS AND METHODS: F-waves reflecting single motor units were recorded with a multi-channel surface electrode array and weak electrical stimulation to the median or ulnar nerves in 21 healthy volunteers. F-MFCVs of the abductor pollicis brevis (APB) and abductor digiti minimi (ADM) were calculated from the F-wave peak latency in each channel. MFCV during minimal voluntary contraction (V-MFVC) was measured in the same muscles. RESULTS: There was no significant difference between F-MFCV and V-MFCV in the muscles tested The mean F-MFCV value was similar to recently reported MFCV values generated by minimal voluntary contraction. No significant differences were found between the APB and ADM F-MFCVs, whereas the MCV of the ulnar nerve was faster than that of the median nerve. CONCLUSION: The MFCV in a single motor unit could be measured with a multi-channel surface electrode array by recording F-waves induced by weak stimulation. Since V-MFCV generated by minimal voluntary contraction is explained by the size principle, V-MFCV reflects small and slow conducting motor unit. There was no significant difference between F-MFCV and V-MFCV. It seemed that F-MFCV also reflected small motor unit. The reason for the lack of difference in the F-MFCVs of the ADM and APB is considered to be a relatively slow F-MFCV. Moreover, MCV reflected the speed of the fastest nerve fiber, whereas F-MFCV did not.

A new method to establish the rational extent of hepatic resection for advanced gallbladder cancer using dye injection through the cystic artery.

BACKGROUND: Hepatic resection has been indicated to eliminate cancer at the surgical margin in cases of advanced gallbladder carcinoma, but there is considerable controversy about the reasonable extent of liver resection. A new on-table dye injection technique has been introduced to determine the venous drainage of the gallbladder and ascertain the amount of liver to remove. METHODS: In four hepatic resections for pT2 gallbladder cancer, indocyanine green solution (25 mg/20 ml) was injected over a period of 30 seconds through the cystic artery. The stained area of the liver surface was completely resected, maintaining a margin of at least 2 cm from the gallbladder. RESULTS: The entire serosal surface of the gallbladder takes on a light green stain immediately after dye injection, and then the liver surface around the gallbladder gradually becomes stained with a clear demarcation line. The distance between the demarcation line and the gallbladder ranged from 1.0 to 5.0 cm. The extent of the stained area differed from one individual to another. Histopathological examination of resected liver specimens revealed that one of the four resected livers had micrometastasis in the portal area 27 mm from the gallbladder wall and there were no cancer cells at the surgical margins. No recurrence has been seen in any of our 4 patients at 16-26 months after operation. DISCUSSION: The dye injection method is useful in determining the appropriate extent of hepatic resection for advanced gallbladder cancer, as it is possible to determine the necessary and sufficient amount of liver parenchyma that should be removed according to the perfusion area of the cystic veins in each individual patient.

[Report on the 13th European Congress of Radiology (ECR): Comparison of primary proton beams and secondary charged-particles].

PURPOSE: In the proton radiotherapy, primary proton beams contribute to the absorbed dose and the share of secondary charged-particles is small. The purpose is to discuss about the ratio of average dose of primary proton beams and secondary charged-particles. METHODS: We performed the dosimetry of 70 MeV proton beams in water using ionization chamber. The ratio of average dose for secondary charged-particles in some range shifter was calculated by the dose ratio of primary and scatter. To exclude the influence of lateral secondary charged-particles, the ratio of average dose for secondary charged-particles was extrapolated to zero field size of each. RESULTS: The ratio of average dose for secondary charged-particles was extrapolated to zero field size by the bi-exponential fit. The ratio of average dose for longitudinal secondary charged-particles for zero fields at each depth is almost the same; the different at the shallow depth is decreased. CONCLUSIONS: The secondary charged-particles from collimator is affected by the dose of shallow depth. The influence of lateral secondary charged-particles in water phantom was excluded with the extrapolation method for zero field size in each depth.

Loss of alveolar basement membrane type IV collagen alpha3, alpha4, and alpha5 chains in bronchioloalveolar carcinoma of the lung.

Type IV collagen, the major component of basement membrane (BM), is composed of six genetically distinct alpha(IV) chains. This study investigated for the first time the expression of these six alpha(IV) chains immunohistochemically, using alpha(IV) chain-specific monoclonal antibodies, in normal lung and in small (less than 2 cm in diameter) adenocarcinoma of the lung with a bronchioloalveolar growth pattern at the periphery. Small adenocarcinomas were histopathologically classified into three subtypes: bronchioloalveolar carcinoma (BAC) without collapse, BAC with collapse, and adenocarcinoma with bronchioloalveolar features. In normal lung, alveolar BM was composed of alpha1(IV)/alpha2(IV) chains and alpha3(IV)/alpha4(IV)/alpha5(IV) chains. In non-collapsed areas of BAC, alveolar BM was composed of linear alpha1(IV)/alpha2(IV) chains and discontinuous alpha3(IV)/alpha4(IV)/alpha5(IV) chains. In collapsed areas of BAC, alveolar BM was composed of linear and thick alpha1(IV)/alpha2(IV) chains only, because of the complete loss of alpha3(IV)/alpha4(IV)/alpha5(IV) chains. In invasive areas of adenocarcinoma with bronchioloalveolar features, alpha1(IV)/alpha2(IV) chains around the cancer cell nests were disrupted, in addition to the complete loss of alpha3(IV)/alpha4(IV)/alpha5(IV) chains. In conclusion, during the process of stromal invasion of lung adenocarcinoma, type IV collagen of alveolar BM is remodelled from the complete type, composed of alpha1(IV)/alpha2(IV)/alpha3(IV)/alpha4(IV)/alpha5(IV) chains, to the incomplete type, composed of only alpha1(IV)/alpha2(IV) chains, before the disruption of alpha1(IV)/alpha2(IV) chains. These findings may help to clarify the molecular mechanisms of cancer invasion.

[The alternative or simultaneous excretion of different species of mycobacteria in atypical mycobacteriosis--15 cases in 7 years].

Five hundreds and five cases of Mycobacterium tuberculosis infection admitted to our hospital during 7 years from 1993 to 1999. Numbers of newly diagnosed cases were 390, of which 329 (84.4%) were bacilli positive with sputum examination on admission. The recurrent cases were 115, of which 55 (47.8%) were bacilli positive cases. During the same period, mycobacteria other than tuberculosis (atypical mycobacteria) were detected in the sputum of other 121 cases. The 63 (52.1%) out of these 121 cases were diagnosed as atypical mycobacteriosis (AM) due to repetitive detection of bacilli with fulfilled the criteria according to the Japanese Mycobacteriosis Research Group of the National Chest Hospitals. The ratio of 63 AM cases to 329 bacilli positive TB cases was 19.1%, but it range from 8.2% to 31.3% year by year. In these 63 AM cases, 9 (14.3%) cases excreted AM bacilli simultaneously or alternately with TB bacilli. The other 15 (23.8%) cases excreted different AM bacilli simultaneously or alternately. The changes or combinations with M. avium and M. intracellulare were most frequently observed (in 12 cases). The manners of changes and combinations with different species were described in detail.

An operated case of lung cancer with pleural plaques: its asbestos bodies, fiber analysis and asbestos exposure.

This case was a 79-year-old man with pleural plaques, which had been pointed out in the left lung field on chest X-ray six years ago. A new shadow in the right chest appeared in 1999 and was closely examined. Cytological class IV carcinoma was detected in his lung tissue obtained by broncho-fiberscope. Lobectomy of the right upper lobe was performed, and calcified pleural plaques were found on the chest wall. The clinical diagnosis was poorly differentiated squamous cell carcinoma, T1N0M0. In World War II when he was 26 years old, he had worked as a boiler man on a battle cruiser for one year. The amount of asbestos bodies (AB) was 3,348 per gram dry lung tissue. The cores of AB and asbestos fibers were examined and showed that amosite was the most prevalent and crocidolite, tremolite and chrysotile were present in that order. After leaving the navy, he had worked as a farmer throughout his life, suggesting that he had never contacted asbestos occupationally after being a boiler man. It is strongly suggested that he had been exposed to asbestos during his work as a boiler man and that produced pleural plaques and lung cancer 50 years' later.

Transient interhemispheric neuronal synchrony correlates with object recognition.

Object recognition might be achieved by the recreation of a meaningful internal image from visual fragments. This recreation might be achieved by neuronal synchronization that has been proposed as a solution for the perceptual binding problem. In this study, we evaluated synchronization between the occipitotemporal regions bilaterally using electroencephalograms during several visual recognition tasks. Conscious recognition of familiar objects spanning the visual midline induced transient interhemispheric electroencephalographic coherence in the alpha band, which did not occur with meaningless objects or with passive viewing. Moreover, there was no interhemispheric coherence when midline objects were not recognized as meaningful or when familiar objects were presented in one visual hemifield. These data suggest a close link between site-specific interregional synchronization and object recognition.

Vascular encasement by pancreatic cancer: correlation of CT findings with surgical and pathologic results.

PURPOSE: The purpose of this study was to correlate thin-slice high-resolution helical CT findings of arterial and venous involvement in pancreatic cancers with surgical and histopathologic results. METHOD: Forty-eight patients with pancreatic cancer underwent preoperative thin-slice high-resolution helical CT, followed by surgical dissection of the pancreatic vessels during curative or palliative surgery. Major vessels running within 1 cm from the tumor margin were evaluated. CT appearance was graded on a 0-4 scale (0: none, 1: <24%, 2: 25-49%, 3: 50-74%, 4: 75-100%) by circumferential contiguity of tumor to vessels. Resected specimens were available from 26 patients. RESULTS: Surgical correlation of CT findings was available in 89 veins and 83 arteries, and both surgical and histologic correlation was available for 42 veins and 29 arteries. At surgical observation, 29 of 35 veins (82.9%) evaluated as CT grade 3 or 4 were found to be involved, whereas only 18 of 30 arteries (60%) evaluated as CT grade 3 or 4 were proved to be involved. On microscopic observation, tumor invasion to the portal venous systems was confirmed in 15 of 42 (35.7%) vessels, and this invasion was depicted as from CT grades 1 to 4. In arteries, tumor invasion was seen in 3 of 29 vessels (10.3%), all of which were graded as 3 or 4 by CT. CONCLUSION: The grading system of vascular invasion should differ between arteries and veins. Involvement of the venous system exceeding one-half circumference of the vessels (grade 3 or 4) was suggestive of vascular invasion; however, this criterion was not always satisfactory for the evaluation of tumor invasion in the arterial system.