A preliminary study on predictors of treatment response to repetitive transcranial magnetic stimulation in patients with treatment-resistant depression in Japan.

BACKGROUND: Brain imaging studies have reported that the effect of repetitive transcranial magnetic stimulation (rTMS) is associated with the activities of the dorsolateral prefrontal cortex (DLPFC) and ventral medial prefrontal cortex (VMPFC). However, few studies have been conducted in Japanese patients. AIM: We aimed to identify brain regions associated with depressive symptom changes by measuring regional cerebral blood flow (rCBF) in the DLPFC and VMPFC before and after the high-frequency rTMS to the left DLPFC in Japanese patients with treatment-resistant depression. METHOD: Fourteen patients participated in the rTMS study and were assessed with the 17-item Hamilton depression rating scale (HAM-D17 ). Among them, 13 participants underwent magnetic resonance imaging scan of the brain using the arterial spin labeling method. The rCBF was calculated using the fine stereotactic region of interest template (FineSRT) program for automated analysis. We focused on eight regions reported in previous studies. RESULTS: Depression severity significantly decreased after 2 week (HAM-D17 :11.4 ± 2.8, P = 0.00027) and 4 week (HAM-D17 : 11.0 ± 3.7, P = 0.0023) of rTMS treatment. There was no significant change in rCBF at each region in the pre-post design. However, there was a significantly negative correlation between baseline rCBF in the right DLPFC and the improvement in HAM-D17 score (r = -0.559, P = 0.047). CONCLUSION: We obtained supportive evidence for the effectiveness of rTMS to the prefrontal cortex in treatment-resistant depression, which may be associated with reduced rCBF of the right DLPFC before initiation of rTMS.

High FDG Uptake in Pleomorphic Hyalinizing Angiectatic Tumor.

PHAT (pleomorphic hyalinizing angiectatic tumor) is a rare, locally aggressive, low-grade mesenchymal neoplasm of uncertain lineage with a predilection for the lower extremities. We report a 74-year-old woman with an enlarging mass on the right popliteal fossa undergoing FDG PET/CT to characterize its biological activity. Increased accumulation of FDG (SUVmax, 23.0) in the solid component of the tumor was seen. Diagnosis of PHAT was confirmed by examination of the surgical resection specimens. This case showed significant FDG accumulation relative to its pathological low-grade malignant nature.

Correlation between anti-thyroid peroxidase antibody levels and diffuse thyroid uptake of 18F-fluorodeoxyglucose in Hashimoto's thyroiditis: a retrospective study.

BACKGROUND: On 18F-fluorodeoxyglucose (FDG)-positron emission tomography (PET), diffuse uptake in the thyroid gland is often observed in patients with Hashimoto's thyroiditis. In this study, we evaluated the factors associated with diffuse uptake by comparing Hashimoto's thyroiditis patients with or without diffuse uptake in the thyroid. METHODS: A retrospective study was conducted of 18 patients with Hashimoto's thyroiditis who underwent blood tests, thyroid ultrasonography, and FDG-PET during the period from 2014 to 2015. The patients were divided into two groups: one with diffuse thyroid uptake (group 1, n = 13) and one without diffuse thyroid uptake (group 2, n = 5). Clinical and laboratory parameters, including maximum standardized uptake in the thyroid (SUVmax), which was defined as the higher value obtained in either the right or left thyroid lobe, were compared in the two groups. RESULTS: The frequency of abnormal findings, such as a rough or heterogeneous pattern, was significantly higher in group 1 (p <  0.01), as were anti-thyroid peroxidase (TPO) antibody titers, anti-thyroglobulin (Tg) antibody titers, and SUVmax (p <  0.01). The frequency of hypothyroidism did not differ significantly in the two groups. Anti-TPO and anti-Tg titers were positively correlated with SUVmax (r = 0.856, p <  0.01 and r = 0.821, p <  0.01, respectively); in univariate analysis, anti-TPO titer was predictive of SUVmax (p <  0.01). CONCLUSIONS: The results of the current study suggest that Hashimoto's thyroiditis patients with high titers of anti-thyroid antibodies are likely to exhibit intense diffuse FDG uptake in the thyroid, and that thyroid function may be clearly impaired, even in the presence of mild FDG uptake in the thyroid.

Usefulness of proton magnetic resonance spectroscopy in predicting positive biopsy after high-intensity focused ultrasound for treatment of localized prostate cancer.

OBJECTIVES: To investigate the clinical effectiveness of proton magnetic resonance spectroscopy in predicting local recurrence or residual disease after high-intensity focused ultrasound for treatment of localized prostate cancer. METHODS: The present study included patients with localized prostate cancer who underwent high-intensity focused ultrasound of whole-gland ablation as primary therapy. Clinicopathological variables including proton magnetic resonance spectroscopy, T2-weighted magnetic resonance imaging, and prostate-specific antigen and its derivatives were analyzed to predict the positive prostate biopsy results using univariate and multivariate analyses. Furthermore, the presence of tumor in each of the 12 prostate sectors by T2-weighted magnetic resonance imaging and proton magnetic resonance spectroscopy were evaluated and compared with prostate biopsy results in each of the 12 prostate sectors in order to evaluate the local cancer distribution in the prostate after high-intensity focused ultrasound. RESULTS: Overall, we carried out 85 prostate biopsies in 52 patients. Multivariate logistic regression analysis showed that the positive finding of proton magnetic resonance spectroscopy was the only statistically significant prognostic parameter of pathological tumor progression in patients after high-intensity focused ultrasound. Prostate biopsy cores were obtained from 952 prostate sectors of 52 patients and 85 prostate biopsies. Compared with T2-weighted magnetic resonance imaging, proton magnetic resonance spectroscopy (sensitivity 52.8%, specificity 97.4%, positive predictive value 44.2% and negative predictive value 98.1%, P < 0.001) has higher values to predict local tumor progression in prostate sectors after high-intensity focused ultrasound. CONCLUSIONS: Proton magnetic resonance spectroscopy is a useful, non-invasive diagnostic modality that predicts local tumor progression in patients after high-intensity focused ultrasound, as well as local cancer distribution at each of the prostate sectors with pinpoint accuracy.

Feasibility of multiparametric prostate magnetic resonance imaging in the detection of cancer distribution: histopathological correlation with prostatectomy specimens.

PURPOSE: To prevent overtreatment, it is very important to diagnose the precise distribution and characteristics of all cancer lesions, including small daughter tumors. The purpose of this study was to evaluate the efficacy of T2-weighted magnetic resonance imaging (T2W), diffusion-weighted magnetic resonance imaging (DWI), magnetic resonance spectroscopy ((1)H-MRS), and prostate biopsy (PBx) in the detection of intraprostatic cancer distribution. METHODS: All patients underwent T2W, DWI, (1)H-MRS, and PBx followed by radical prostatectomy (RP). Individual prostates were divided into 12 segmental regions, each of which was examined for the presence or absence of malignancy on the basis of T2W, DWI, (1)H-MRS, and PBx, respectively. These results were compared with the histopathological findings for RP specimens. RESULTS: We included 54 consecutive patients with biopsy-proven prostate cancer (mean age, 62.7 years; median prostate-specific antigen level, 5.7 ng/mL) in this study. We could detect cancer in 247 of 540 evaluable lesions. The area under the receiver operator characteristic curve analysis yielded a higher value for DWI (0.68) than for T2W (0.65), (1)H-MRS (0.54), or PBx (0.56). In 180 cancerous regions of RP specimens with false-negative PBx results, T2W+DWI had the highest positive rate (53.3%) compared with that of each sequence alone, including T2W (45.6%), DWI (41.1%), and (1)H-MRS (30.0%). CONCLUSIONS: Multiparametric magnetic resonance imaging (T2W, (1)H-MRS, DWI) enables the detection of prostate cancer distribution with reasonable sensitivity and specificity. T2W+DWI was particularly effective in detecting cancer distribution with false-negative PBx results.

The breath test system involving a novel tracer, ¹³C-uracil and Wagner-Nelson analysis: comparison with the gastric emptying scintigraphy.

BACKGROUND/AIMS: In this pilot study, a new breath test system for gastric emptying study has been proposed. METHODOLOGY: The system involves 13C-uracil as a novel tracer and the Wagner-Nelson method for analyzing breath data. RESULTS: In three healthy volunteers, the new breath system allowed quantification of gastric emptying profiles as accurately as the scintigraphic technique. CONCLUSIONS: Further validation studies with a lager sample size are needed.

Regional cerebral blood flow abnormalities in patients with kawasaki disease.

PURPOSE: Kawasaki disease (KD) is an acute febrile disorder of unknown etiology. Brain single-photon emission computed tomography (SPECT) and magnetic resonance imaging (MRI) help in detecting regional cerebral blood flow abnormalities and brain damage. The usefulness of SPECT and MRI in patients with KD was evaluated. MATERIALS AND METHODS: All 22 patients with KD underwent brain SPECT using Tc-99m-hexamethyl propylene amine oxime from 6 days to 3 years after onset, and 8 patients underwent brain MRI. Of the 22 patients, 4 had neurologic symptoms. Case 1 showed prolonged apnea; case 2, prolonged disturbance of consciousness; and cases 3 and 4 generalized tonic-clonic seizures. Initial brain SPECT showed localized hypoperfusion in 4 and 13 patients with and without neurologic symptoms, respectively. RESULTS: All patients with neurologic symptoms underwent follow-up SPECT; localized hypoperfusion was detected between 1- and 6-month follow-up in 3 of these patients. Six patients without neurologic symptoms underwent follow-up SPECT. Localized hypoperfusion was detected at approximately 1- to 11-month follow-up in 4 of these patients. Diffusion-weighted imaging revealed abnormal high-intensity areas in the corpus callosum in case 1. Case 2 showed a bilateral chronic subdural hematoma with decreased size and ischemic changes, and case 3 showed bilateral hippocampal atrophy and left hippocampal sclerosis. CONCLUSIONS: Because the occurrence of localized hypoperfusion is possibly not restricted to only the acute phase in KD, brain SPECT and MRI should also be performed in KD patients with neurologic symptoms.

Iconic memory and parietofrontal network: fMRI study using temporal integration.

We investigated the neural basis of iconic memory using functional magnetic resonance imaging. The parietofrontal network of selective attention is reportedly relevant to readout from iconic memory. We adopted a temporal integration task that requires iconic memory but not selective attention. The results showed that the task activated the parietofrontal network, confirming that the network is involved in readout from iconic memory. We further tested a condition in which temporal integration was performed by visual short-term memory but not by iconic memory. However, no brain region revealed higher activation for temporal integration by iconic memory than for temporal integration by visual short-term memory. This result suggested that there is no localized brain region specialized for iconic memory per se.

Parietal and frontal object areas underlie perception of object orientation in depth.

Recent studies have shown that the human parietal and frontal cortices are involved in object image perception. We hypothesized that the parietal/frontal object areas play a role in differentiating the orientations (i.e., views) of an object. By using functional magnetic resonance imaging, we compared brain activations while human observers differentiated between two object images in depth-orientation (orientation task) and activations while they differentiated the images in object identity (identity task). The left intraparietal area, right angular gyrus, and right inferior frontal areas were activated more for the orientation task than for the identity task. The occipitotemporal object areas, however, were activated equally for the two tasks. No region showed greater activation for the identity task. These results suggested that the parietal/frontal object areas encode view-dependent visual features and underlie object orientation perception.

Coronary artery stent evaluation using a vascular model at 64-detector row CT: comparison between prospective and retrospective ECG-gated axial scans.

OBJECTIVE: We wanted to evaluate the performance of prospective electrocardiogram (ECG)-gated axial scans for assessing coronary stents as compared with retrospective ECG-gated helical scans. MATERIALS AND METHODS: As for a vascular model of the coronary artery, a tube of approximately 2.5-mm inner diameter was adopted and as for stents, three (Bx-Velocity, Express2, and Micro Driver) different kinds of stents were inserted into the tube. Both patent and stenotic models of coronary artery were made by instillating different attenuation (396 vs. 79 Hounsfield unit [HU]) of contrast medium within the tube in tube model. The models were scanned with two types of scan methods with a simulated ECG of 60 beats per minute and using display field of views (FOVs) of 9 and 18 cm. We evaluated the in-stent stenosis visually, and we measured the attenuation values and the diameter of the patent stent lumen. RESULTS: The visualization of the stent lumen of the vascular models was improved with using the prospective ECG-gated axial scans and a 9-cm FOV. The inner diameters of the vascular models were underestimated with mean measurement errors of -1.10 to -1.36 mm. The measurement errors were smaller with using the prospective ECG-gated axial scans (Bx-Velocity and Express2, p < 0.0001; Micro Driver, p = 0.0004) and a 9-cm FOV (all stents: p < 0.0001), as compared with the other conditions, respectively. The luminal attenuation value was overestimated in each condition. For the luminal attenuation measurement, the use of prospective ECG-gated axial scans provided less measurement error compared with the retrospective ECG-gated helical scans (all stents: p < 0.0001), and the use of a 9-cm FOV tended to decrease the measurement error. CONCLUSION: The visualization of coronary stents is improved by the use of prospective ECG-gated axial scans and using a small FOV with reduced blooming artifacts and increased spatial resolution.

Clinical efficacy of proton magnetic resonance spectroscopy (1H-MRS) in the diagnosis of localized prostate cancer.

BACKGROUND: The objective of this study was to evaluate the efficacy of proton magnetic resonance spectroscopy (1H-MRS) in the detection of prostate cancer. MATERIALS AND METHODS: The experimental group consisted of 20 patients with localized prostate cancer who underwent radical prostatectomy. The sensitivity, positive predictive value and accuracy of the detection of prostate cancer in the 12 sections of the peripheral zone were calculated for prostate biopsy alone, 1H-MRS alone and the combination of these methods, respectively. RESULTS: The sensitivity, the positive predictive value, and the accuracy of the preoperative diagnosis of prostate cancer were 43.7%, 68.9% and 54.6%, respectively, with prostate biopsy alone; 60.6%, 87.8% and 71.4% with 1H-MRS alone; and 88.7%, 88.7% and 87.4% with the combination of biopsy and 1H-MRS, respectively. Combined use of biopsy and 1H-MRS significantly improved the sensitivity, positive predictive value and accuracy of the diagnosis. CONCLUSION: 1H-MRS together with biopsy might improve the diagnostic accuracy in prostate cancer.

Detection of in-stent restenosis of coronary stents using 40-detector row computed tomography in vitro.

OBJECTIVE: To evaluate the performance of 40-detector row computed tomography (CT) in the detection of in-stent stenosis of coronary stents. METHODS: Seven patent vascular models, 7 stenotic models, and 7 obstructed models were scanned with a 40-detector CT. We made the vascular models using 3 types of stent (Bx-Velocity, Express2, Driver) with an inner diameter of about 2.5, 3.0, or 3.5 mm. We measured the stent lumen diameter and evaluated the in-stent stenosis visually for the 21 vascular models. We evaluated attenuation values of the stent lumen of the 9 patent models of 2.5-mm diameter. RESULTS: The inner diameters of the vascular models were underestimated by CT with mean measurement errors of -1.19 to -1.49 mm. The absolute mean overall measurement error decreased as the inner diameter increased. The direct visualization of in-stent stenosis was possible for the 3.0- and 3.5-mm diameter models, but impossible for the 2.5-mm diameter models. For patent vascular models of 2.5-mm diameter, the CT attenuation inside the stent was significantly higher than that of the unstented portion (P < 0.0001). For obstructed vascular models of 2.5-mm diameter, the CT attenuation inside the stent was significantly lower than that of the unstented portion (P < 0.0001). Also for stenotic vascular models of 2.5-mm diameter, the CT attenuation inside the stent was lower than that of the unstented portion. CONCLUSIONS: Visualization of stent lumen on CT is affected by the stent diameter. Measurement of stent lumen is useful for detection of in-stent stenosis, when the direct visualization of in-stent stenosis is impossible.

Real-time MRI of orthotopic ileal neobladder voiding: preliminary findings.

OBJECTIVES: The purpose of this preliminary study was to analyze the dynamic changes in the configuration of the neobladder and naïve bladder during voiding using real-time MRI. METHODS: This study included 10 male patients who had a radical cystectomy and an ileal orthotopic neobladder due to organ-confined bladder cancer and had good urinary function, and 5 male control volunteers. With the subjects in the lateral decubitus position, real-time MRI was performed during micturition. A sagittal slice orientation was used to depict the bladder and the entire length of the urethra; individual movements along the X-axis and Y-axis of the bottom and top of the neobladder and the naïve bladder were recorded and analyzed. Urodynamic studies (UDS) and video voiding cystourethrography were performed in patients. RESULTS: Five of the 10 neobladder patients could void in the lateral decubitus position. In normal controls and patients who could void, the bladder outlet bladder moved ventrocranially during micturition. The ileal bladder outlet moved a significantly longer distance than the naïve bladder during micturition (X-axis, -13.4+/-1.5 vs. -3.6+/-4.3 cm, p=0.0014; Y-axis, -10.6+/-0.5 vs. -2.0+/-6.5 cm, p=0.0187). The distance that the bladder top moved between the naïve bladders and the neobladder did not differ. UDS did not show a difference between patients who could and could not void at lateral position. CONCLUSIONS: During micturition, the neobladder was found to rotate and move more dynamically than the naïve bladder. Real-time MRI is useful for assessing dynamic voiding function of orthotopic neobladders.

Assessment of coronary stents using 40-detector row CT: comparison with 16-detector row CT in vitro.

OBJECTIVE: To evaluate the performance of 40-detector row computed tomography (CT) in the assessment of coronary stents in comparison with 16-detector row CT. METHODS: A total of 6 vascular models (3 models without stenosis and 3 with stenosis) using 3 types of stent (Bx-Velocity, Express2, and Driver) with an approximately 3.5-mm inner diameter filled with contrast material (450 Hounsfield units) were scanned with 2 computed tomographic scanners (collimation, 16 x 0.75 and 40 x 0.625 mm). We evaluated the in-stent stenosis visually for the 6 vascular models in 4 orientations (0, 30, 60, and 90 degrees) to the z-axis of the scanner. We evaluated attenuation values of the stent lumen of the 3 patent models in the 4 orientations. The average and standard deviation of the luminal attenuation values were assessed to evaluate the degree of blooming and streak artifacts. RESULTS: The visualization of the stent lumen of the vascular models at 90 degrees was improved using 40-detector row CT. For all the 3 stents, the average luminal attenuations values using 40-detector row CT were significantly lower than those using 16-detector row CT in all orientations. For all the 3 stents, the standard deviations of the luminal computed tomographic attenuation using 40-detector row CT were significantly smaller than those using 16-detector row CT in the 4 orientations to the z-axis except for Express 2 at 0 degrees. CONCLUSIONS: The visualization of coronary stents is improved by the use of 40-detector row CT with reduced blooming and streak artifacts.

Assessment of coronary stent in vitro on multislice computed tomography angiography: improved in-stent visibility by the use of 140-kV tube voltage.

OBJECTIVE: To assess the effect of tube voltage on the in-stent visibility of coronary stents in vitro on computed tomography (CT) angiography. METHODS: A total of 6 vascular models (3 models without stenosis and 3 with stenosis) using 3 kinds of stent (Bx Velocity, Express2, and Driver) with an inner diameter of approximately 3.5 mm and filled with contrast material (CT attenuation, 450 Hounsfield units) were scanned by means of a 16-detector row CT. We assessed the visual stenosis evaluation and inhomogeneity of stent lumen in 4 orientations (0-, 30-, 60-, and 90-degree angles) relative to the z-axis of the scanner using 3 imaging techniques (120-kV tube voltage using a medium convolution kernel, 120-kV tube voltage using a convolution kernel for bone, and 140-kV tube voltage using a convolution kernel for bone). Statistical analysis involved F test with a statistical significance of P < 0.05. RESULTS: The convolution kernel for bone made it easier to evaluate the stenosis inside the stents, although it increased the luminal inhomogeneity significantly (Bx Velocity and Express2, P < 0.005; Driver, P < 0.05). The luminal inhomogeneity tended to increase as the strut diameter and the weight per unit length increased. Using 120-kV tube voltage, the luminal inhomogeneity inside the stents was at the minimum in the angle of 0 degree relative to the z-axis, and at the maximum in the angle of 90 degrees, except for Driver. The 140-kV tube voltage was effective for the improvement of luminal inhomogeneity and visibility of in-stent stenosis compared with the 120-kV tube voltage. CONCLUSIONS: The in-stent visibility of coronary stents on CT angiography can be improved by the use of 140-kV tube voltage with the convolution kernel for bone.

Interindividual uniformity and variety of the "Writing center": a functional MRI study.

Our aim is to investigate the neural substrates for writing using fMRI (twenty right-handed subjects). We assumed that common areas involved in both writing with right and left hands are crucial to the central process of writing. We employed Japanese phonograms (Kana), in which phoneme-grapheme conversion would be extremely simple. Brain activation was examined under three conditions: (1) written naming with the right hand (WR), (2) written naming with the left hand (WL), and (3) naming silently (NA). While the comparison of WR to NA (WR>NA) exhibited activation only in the left frontoparietal area, the WL>NA comparison exhibited broader activation than the WR>NA comparison, i.e., the left frontoparietal area except the motor and sensory areas and the right frontoparietal area. A conjunction analysis in SPM2 revealed common areas of activation across the WR>NA and WL>NA comparisons, which are assumed to be crucial to writing. In the group analysis, three areas were found to be activated: the posterior end of the left superior frontal gyrus, which is superior and posterior to Exner's center; the anterior part of the left superior parietal lobule; and the lower part of the anterior limb of the left supramarginal gyrus. In the single-subject analysis, whereas the first two of the above three areas were found to be crucial for writing in all individuals, an interindividual inconsistency of involvement with writing was observed in three areas: the lower part of the anterior limb of the left supramarginal gyrus (60% involved); the right frontal region (47%); and the right intraparietal sulcus (47%).

Accuracy of attenuation measurement of vascular wall in vitro on computed tomography angiography: Effect of wall thickness, density of contrast medium, and measurement point.

OBJECTIVES: We sought to assess the effects of measurement point, wall thickness, and intravascular density of contrast material on attenuation measurement of vascular wall. MATERIALS AND METHODS: We used vascular models (actual attenuation value of the wall: 83 HU) with wall thicknesses of 1.5, 1.0, or 0.5 mm, filled with contrast material of 254, 325, or 400 HU. The 9 vascular models were fixed in an oil-filled container and scanned with a 16-detector computed tomography. The wall attenuation values were measured at 1 point for 0.5-mm thickness models, 3 for 1.0-mm thickness models, and 5 for 1.5-mm thickness models with the same interval of 0.25 mm. Total 20 measurements were done for each point. RESULTS: For 1.0-mm and 1.5-mm thickness models, wall attenuation progressively increased as the measurement points approached the lumen (P < 0.0001). At all the measurement points for 0.5-mm and 1.0-mm thickness models and the 2 inner measurement points for 1.5-mm thickness models, the densities of contrast material affected the wall attenuations significantly (P < 0.0001). At the midportion for 1.5-mm thickness models, the wall attenuations were not affected by the densities of the contrast material (P = 0.6301), and were 65-68 HU. CONCLUSIONS: The effects of the intravascular density of contrast material, measurement point, and wall thickness should be considered in the attenuation measurement of the wall.

Detection of cerebral blood flow changes during repetitive transcranial magnetic stimulation by recording hemoglobin in the brain cortex, just beneath the stimulation coil, with near-infrared spectroscopy.

Many studies measured cerebral blood flow changes in the stimulated primary motor cortex during repetitive transcranial magnetic stimulation (rTMS) using PET, SPECT, and fMRI; however, most of these procedures are associated with problems related to temporal resolution and magnetic field artifacts that are produced by rTMS. In this study of 12 healthy right-handed volunteers, we measured the hemoglobin (Hb) concentration change in the stimulated primary motor cortex during and after rTMS using rTMS coil and near infrared spectroscopy (NIRS) with high temporal sampling (every 125 ms). The left primary motor cortex that controls the right first dorsal interosseus (FDI) muscle was stimulated 10 times with an angle figure-of-eight coil at a frequency of 0.5 or 2 Hz, at intensity of 80% or 120% of resting motor threshold (RMT). We used 4 stimulus conditions: (1) 2 Hz-120% RMT, (2) 2 Hz-80% RMT, (3) 0.5 Hz-120% RMT, and (4) 0.5 Hz-80% RMT. We observed small intensity-dependent increments in total- and oxy-Hb concentrations around 5 s at the 120% RMT condition. Greater decrements in total- and oxy-Hb concentrations and increment of deoxy-Hb concentration were observed during and after rTMS at all conditions, both at the supra-threshold and sub-threshold stimulus intensities. Our results emphasize the suitability of NIRS combined with rTMS for detecting changes in cerebral blood flow.

Impact of 16-slice computed tomography in percutaneous coronary intervention of chronic total occlusions.

The main reason for failure of percutaneous coronary intervention (PCI) of chronic total occlusion (CTO) is because the calcified plaque prevents the guide wire crossing the occlusion. We aimed to identify the route, and characterize plaque components within CTO, using 16-slice computed tomography (MSCT). Twenty three angiographic CTO in 22 patients (mean age 69 +/- 5 years, 17 males) were included. All patients had undergone MSCT prior to PCI. Images were analyzed for lesion visibility and plaque characteristics of CTO. The presence and location of calcified plaque within the CTO were systematically assessed. Each lesion was classified as a noncalcified, moderately calcified, or exclusively calcified plaque. Procedural failure was defined as the inability to cross a guide wire through the occlusion. All coronary routes of CTO segment were visualized. MSCT revealed three markedly bent CTO segments (13.0%), which could not be identified by coronary angiography only. Calcified plaques were detected in 30 lesions of 19 CTO segments (82.6%), but were not detected in the other four. The majority of calcified plaque was located in the proximal lesion, or both proximal and distal lesions. Fifteen out of 30 calcified lesions (50.0%) were exclusively calcified plaques. Overall procedural success was obtained in 21 CTOs (91.3%). MSCT can accurately identify the route of the CTO segment and evaluate both distribution and amount of the calcified plaque within it. Even with the complicated and/or calcified lesions, PCI success rate was excellent under MSCT guidance. MSCT should become a useful tool in PCI of CTO.