Cervical intervertebral separation caused by trauma on post-mortem computed tomography: Possibility of a diagnosis based on intervertebral gas.

OBJECTIVES: Gas is a common finding in cervical intervertebral separation. However, intervertebral gas is also found in many decedents without intervertebral separation. Here, we quantified intervertebral gas and examined its value in the diagnosis of cervical intervertebral separation. METHODS: We retrospectively reviewed data from 1118 decedents who underwent post-mortem computed tomography (CT) and autopsy from May 2011 to July 2016 and selected those with cervical intervertebral gas with or without intervertebral separation. These data comprised 56 cervical intervertebral spaces with gas [intervertebral separation in 19 (33.9%)] in 43 subjects [intervertebral separation in 17 (39.5%)]. We categorised the decedents according to gas volume, position, and shape and determined the significance of the differences between the decedents with and without separation. RESULTS: The gas volume did not differ significantly between decedents with and without separation (p = 0.063). However, there were significant differences in the gas position between decedents with and without separation. In the sagittal plane: gas was seen in the "centred" position in the ventral-to-dorsal direction in more decedents without separation than in those with separation (p = 0.018). Gas was seen in the ventral-to-dorsal positions in more decedents with separation than in those without separation (p = 0.049). In the cranio-caudal direction, gas in the upper position was more common in decedents with separation than in those without separation in the sagittal plane (p = 0.03). In the coronal plane: gas was seen in the upper position more frequently in decedents with separation in the cranio-caudal direction than in those without separation (p = 0.001). A significant difference in gas shape was observed only in the coronal plane (p = 0.024); irregular gas was associated with decedents without separation. CONCLUSION: Gas in the ventral-to-dorsal and upper positions in the sagittal plane and in the upper position in the coronal plane was rather indicative of cervical intervertebral separation. An irregular gas shape in the coronal plane was indicative of degenerative changes.

Evaluating clinical implications of 15-mega-sub-pixel liquid-crystal display in phase-contrast mammography.

BACKGROUND: Phase-contrast mammography (PCM) systems characteristically yield sharp images with edge enhancement and high-resolution 25-µm/pixel mammograms. However, not all PCM image information can be shown on the display at a resolution of 5-megapixel (5-MP), although 5-MP monitors are recommended for interpretation of digital mammograms. Therefore, we investigated the potential utility of a 15-mega-sub-pixel (15-MsP) display for PCM images. METHODS: We used a monitor that offered both 5-MP and 15-MsP displays by using a sub-pixel drive (SPD) technique to increase the spatial resolution of the monitor by threefold in the direction of the sub-pixels. Contrast-detail mammography phantom images were evaluated visually by four radiologic technologists. In this study, four display magnification ratios were used and the calculated image quality figures (IQFs) were compared with those of a 5-MP display. RESULTS: The detection capability of the 15-MsP display was significantly better than that of the 5-MP display at magnification ratios of 49 and 100 %. At other magnification ratios, the detection capability of the 15-MsP display was higher than that of the 5-MP display, but the difference was not significant. CONCLUSIONS: A 15-MsP display has the potential to provide better detection than that provided by conventional 5-MP displays. A 15-MsP display using SPD technology is suitable for high-resolution digital mammograms, such as those produced by PCM systems.

Distinction between saltwater drowning and freshwater drowning by assessment of sinus fluid on post-mortem computed tomography.

OBJECTIVE: To evaluate the difference in sinus fluid volume and density between saltwater and freshwater drowning and diagnose saltwater drowning in distinction from freshwater drowning. METHODS: Ninety-three drowning cases (22 saltwater and 71 freshwater) were retrospectively investigated; all had undergone post-mortem CT and forensic autopsy. Sinus fluid volume and density were calculated using a 3D-DICOM workstation, and differences were evaluated. Diagnostic performance of these indicators for saltwater drowning was evaluated using a cut-off value calculated by receiver operating characteristic (ROC) analysis. RESULTS: The median sinus fluid volume was 5.68 mL in cases of saltwater drowning (range 0.08 to 37.55) and 5.46 mL in cases of freshwater drowning (0.02 to 27.68), and the average densities were 47.28 (14.26 to 75.98) HU and 32.56 (-14.38 to 77.43) HU, respectively. While sinus volume did not differ significantly (p = 0.6000), sinus density was significantly higher in saltwater than freshwater drowning cases (p = 0.0002). ROC analysis for diagnosis of saltwater drowning determined the cut-off value as 37.77 HU, with a sensitivity of 77 %, specificity of 72 %, PPV of 46 % and NPV of 91 %. CONCLUSION: The average density of sinus fluid in cases of saltwater drowning was significantly higher than in freshwater drowning cases; there was no significant difference in the sinus fluid volume. KEY POINTS: • Sinus fluid density of saltwater drowning is significantly higher than freshwater drowning. • Cut-off value was 37.77 HU based on the ROC analysis. • The cut-off value translated to 91 % NPV for diagnosis of saltwater drowning.

Post-mortem computed tomography findings of the lungs: Retrospective review and comparison with autopsy results of 30 infant cases.

OBJECTIVES: Infant cases frequently show a diffuse increase in the concentration of lung fields on post-mortem computed tomography (PMCT). However, the lungs often show simply atelectasis at autopsy in the absence of any other abnormal changes. Thus, we retrospectively reviewed the PMCT findings of lungs following sudden infant death and correlated them with the autopsy results. MATERIALS AND METHODS: We retrospectively reviewed infant cases (0 year) who had undergone PMCT and a forensic autopsy at our institution between May 2009 and June 2013. Lung opacities were classified according to their type; consolidation, ground-glass opacity and mixed, as well as distribution; bilateral diffuse and areas of sparing. Statistical analysis was performed to assess the relationships among lung opacities, causes of death and resuscitation attempt. RESULTS: Thirty infant cases were selected, which included 22 sudden and unexplained deaths and 8 other causes of death. Resuscitation was attempted in 22 of 30 cases. Bilateral diffuse opacities were observed in 21 of the 30 cases. Of the 21 cases, 18 were sudden and unexplained deaths. Areas of sparing were observed in 4 sudden and unexplained deaths and 5 other causes of death. Distribution of opacities was not significantly associated with causes of death or resuscitation attempt. The 21 cases with bilateral diffuse opacities included 6 consolidations (4 sudden and unexplained deaths, 2 other causes of death), 4 ground-glass opacities (3 sudden and unexplained deaths and 1 other) and 11 mixed (11 sudden and unexplained deaths). Types of opacities were not significantly associated with causes of death or resuscitation attempt. CONCLUSION: Atelectasis is very common in sudden and unexplained death of infants. Bilateral diffuse mixed opacity was observed only in sudden and unexplained deaths. Bilateral diffuse pure consolidation or ground-glass opacity was also observed in other causes of death.

Cost-effectiveness analysis for breast cancer screening: double reading versus single + CAD reading.

BACKGROUND: Computer-aided detection (CAD) increases breast cancer detection, but its cost-effectiveness is unknown for breast cancer screening in Japan. We aimed to determine whether screening mammography diagnosed by one physician using CAD is cost-effective when compared with the standard double reading by two physicians. METHODS: We established our model with a decision tree and Markov model concept based on feasible screening and clinical pathways, combined with prognosis of the health state transition of breast cancer. Cost-effectiveness analysis between double reading by two readers and single reading with CAD by one reader was performed from a social perspective in terms of the expected cost, life expectancy and incremental cost-effectiveness ratio (ICER). The hypothetical population comprised 50-year-old female breast cancer screening examinees. Only direct medical costs related to breast cancer screening and treatment were considered. One simulation cycle was 2 years, and the annual discount rate was 3 %. Sensitivity analysis was performed to evaluate the robustness of the model and input data. RESULTS: Single reading with CAD increased expected costs by 2,704 yen and extended life expectancy by 0.0087 years compared with double reading. The ICER was 310,805 yen per life year gained, which is below the threshold. Sensitivity analysis showed that the sensitivity and specificity of CAD and the number of breast cancer screening examinees greatly affected the results. CONCLUSIONS: Single reading using CAD in mammography screening is more cost-effective than double reading, although the results are highly sensitive to the sensitivity and specificity of CAD and the numbers of examinees.

Diagnosis of drowning using post-mortem computed tomography based on the volume and density of fluid accumulation in the maxillary and sphenoid sinuses.

Recent studies have reported that drowning victims frequently have fluid accumulation in the paranasal sinuses, most notably the maxillary and sphenoid sinuses. However, in our previous study, many non-drowning victims also had fluid accumulation in the sinuses. Therefore, we evaluated the qualitative difference in fluid accumulation between drowning and non-drowning cases in the present study. Thirty-eight drowning and 73 non-drowning cases were investigated retrospectively. The fluid volume and density of each case were calculated using a DICOM workstation. The drowning cases were compared with the non-drowning cases using the Mann-Whitney U-test because the data showed non-normal distribution. The median fluid volume was 1.82 (range 0.02-11.7) ml in the drowning cases and 0.49 (0.03-8.7) ml in the non-drowning cases, and the median fluid density was 22 (-14 to 66) and 39 (-65 to 77) HU, respectively. Both volume and density differed significantly between the drowning and non-drowning cases (p=0.001, p=0.0007). Regarding cut-off levels in the ROC analysis, the points on the ROC curve closest (0, 1) were 1.03ml (sensitivity 68%, specificity 68%, PPV 53%, NPV 81%) and 27.5 HU (61%, 70%, 51%, 77%). The Youden indices were 1.03ml and 37.8 HU (84%, 51%, 47%, 86%). When the cut-off level was set at 1.03ml and 27.5HU, the sensitivity was 42%, specificity 45%, PPV 29% and NPV 60%. When the cut-off level was set at 1.03ml and 37.8HU, sensitivity was 58%, specificity 32%, PPV 31% and NPV 59%.

Binding of lurasidone, a novel antipsychotic, to rat 5-HT7 receptor: analysis by [3H]SB-269970 autoradiography.

Lurasidone is a novel antipsychotic agent with high affinity for dopamine D(2) and serotonin 5-HT(7), 5-HT(2A), and 5-HT(1A) receptors. We previously reported that in addition to its antipsychotic action, lurasidone shows beneficial effects on mood and cognition in rats, likely through 5-HT(7) receptor antagonistic actions. In this study, we evaluated binding of lurasidone to 5-HT(7) receptors in the rat brain by autoradiography using [(3)H]SB-269970, a specific radioligand for 5-HT(7) receptors. Brain slices were incubated with 4 nM [(3)H]SB-269970 at room temperature and exposed to imaging plates for 8 weeks before phosphorimager analysis. Using this method, we first investigated 5-HT(7) receptor distribution. We found that 5-HT(7) receptors are abundantly localized in brain limbic structures, including the lateral septum, thalamus, hypothalamus, hippocampus, and amygdala. On the other hand, its distribution was moderate in the cortex and low in the caudate putamen and cerebellum. Secondly, binding of lurasidone, a selective 5-HT(7) receptor antagonist SB-656104-A and an atypical antipsychotic olanzapine to this receptor was examined. Lurasidone, SB-656104-A (10­1000 nM), and olanzapine (100­10,000 nM) showed concentration-dependent inhibition of [(3)H]SB-269970 binding with IC(50) values of 90, 49, and 5200 nM, respectively. Similar inhibitory actions of these drugs were shown in in vitro [(3)H]SB-269970 binding to 5-HT(7) receptors expressed in Chinese hamster ovary cells. Since there was no marked species difference in rat and human 5-HT(7) receptor binding by lurasidone (K(i) = 1.55 and 2.10 nM, respectively), these findings suggest that binding to 5-HT(7) receptors might play some role in its beneficial pharmacological actions in schizophrenic patients.

Hypothermic death: possibility of diagnosis by post-mortem computed tomography.

Referring to our experience with post-mortem computed tomography (CT), many hypothermic death cases presented a lack of increase in lung-field concentration, blood clotting in the heart, thoracic aorta or pulmonary artery, and urine retention in the bladder. Thus we evaluated the diagnostic performance of post-mortem CT on hypothermic death based on the above-mentioned three findings. Twenty-four hypothermic death subjects and 53 non-hypothermic death subjects were examined. Two radiologists assessed the presence or lack of an increase in lung-field concentration, blood clotting in the heart, thoracic aorta or pulmonary artery, and measured urine volume in the bladder. Pearson's chi-square test and Mann-Whitney U-test were used to assess the relationship between the three findings and hypothermic death. The sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) of the diagnosis were also calculated. Lack of an increase in lung-field concentration and blood clotting in the heart, thoracic aorta or pulmonary artery were significantly associated with hypothermic death (p=0.0007, p<0.0001, respectively). The hypothermic death cases had significantly more urine in the bladder than the non-hypothermic death cases (p=0.0011). Regarding the diagnostic performance with all three findings, the sensitivity was 29.2% but the specificity was 100%. These three findings were more common in hypothermic death cases. Although the sensitivity was low, these findings will assist forensic physicians in diagnosing hypothermic death since the specificity was high.

A Hybrid Image Filtering Method for Computer-Aided Detection of Microcalcification Clusters in Mammograms.

The presence of microcalcification clusters (MCs) in mammogram is a major indicator of breast cancer. Detection of an MC is one of the key issues for breast cancer control. In this paper, we present a highly accurate method based on a morphological image processing and wavelet transform technique to detect the MCs in mammograms. The microcalcifications are firstly enhanced by using multistructure elements morphological processing. Then, the candidates of microcalcifications are refined by a multilevel wavelet reconstruction approach. Finally, MCs are detected based on their distributions feature. Experiments are performed on 138 clinical mammograms. The proposed method is capable of detecting 92.9% of true microcalcification clusters with an average of 0.08 false microcalcification clusters detected per image.

Assessment of the relationship between drowning and fluid accumulation in the paranasal sinuses on post-mortem computed tomography.

Recent reports have detailed common computed tomography (CT) findings in drowning victims, most notably fluid accumulation in the maxillary and sphenoidal sinuses. This CT finding could help forensic doctors to diagnose drowning. This study retrospectively investigated 151 subjects: 39 drowning and 112 non-drowning cases. Pearson's chi-square tests demonstrated that fluid accumulation in the maxillary or sphenoidal sinuses was associated significantly with drowning (p=0.0001). The sensitivity of the drowning diagnosis was 97%, specificity was 35%, accuracy was 51%, positive predictive value was 34% and negative predictive value was 98%. Drowning was significantly associated with fluid accumulation in the maxillary and sphenoidal sinuses, but the specificity and positive predictive value of the drowning diagnosis were poor. Although the presence of fluid in the maxillary and sphenoidal sinuses cannot be used to diagnose drowning, the absence of the fluid can be used to virtually exclude drowning.

Postmortem computed tomography images of a broken piece of a weapon in the skull.

The use of post-mortem radiological imaging is becoming increasing widespread in forensic medicine. These images can help improve the quality and safety of autopsy. We report two cases of homicide victims that had broken pieces of a weapon in their skull. Postmortem multislice computed tomography (MSCT) demonstrated metal artifacts in the skull of two homicide cases. Autopsy showed that both artifacts were pieces broken off of a sharp instrument. Some possible benefits of postmortem MSCT include the ability to reconstruct visual images of weapons and the possible prevention of injury to autopsy personnel.

The fatal risk in hepatic artery embolization for hemostasis after pancreatic and hepatic surgery: importance of collateral arterial pathways.

PURPOSE: To assess retrospectively the cause of hepatic failure related to hepatic arterial embolization (HAE) for hemostasis after pancreaticoduodenectomy or hepatic lobectomy. MATERIALS AND METHODS: Between June 1993 and March 2006, Twenty HAEs in 17 patients (15 men, two women; mean age, 64 years) were performed. Angiographic findings, including portal vein stenosis, collateral arterial pathways after HAE, and the difference of embolic materials, were recorded. The morbidity (hepatic failure and abscess) and mortality were detailed according to collateral arterial pathways, portal vein stenosis, and embolic material used. RESULTS: Bleeding was controlled in all patients, although two patients required repeat embolization. Hepatic failure (n = 8) and abscess (n = 2) arose in nine of 20 HAEs. Death occurred after six of eight HAEs complicated by hepatic failure. The morbidity and mortality rates of HAE were 45% and 30%, respectively. Hepatic complication was eight times more likely to occur (P = .005) in cases with no hepatic collaterals involving hepatic, replaced, or accessory hepatic arteries. Death was observed only in the cases without hepatic collaterals (P = .011). The correlation between the embolization outcome and the presence of portal vein stenosis or the difference of embolic materials was not significant (P > .61). CONCLUSIONS: HAE can be used to successfully control bleeding secondary to hepatic arterial rupture. In the absence of hepatic collaterals, collateral circulation distal to the occlusion from nonhepatic sources may be inadequate and lead to hepatic failure after HAE.

The effects of selective antagonists of serotonin 5-HT7 and 5-HT1A receptors on MK-801-induced impairment of learning and memory in the passive avoidance and Morris water maze tests in rats: mechanistic implications for the beneficial effects of the novel atypical antipsychotic lurasidone.

We have previously reported that lurasidone, a novel atypical antipsychotic with potent serotonin 5-HT(7) antagonist and 5-HT(1A) partial agonist activities, is superior to other antipsychotics in improving the N-methyl-D-aspartate (NMDA) receptor antagonist MK-801-induced learning and memory impairment in the passive avoidance (PA) and Morris water maze (MWM) tests in rats. In this study, we investigated the effects of selective antagonists of 5-HT(7) and 5-HT(1A) receptors (SB-656104-A and WAY-100635, respectively) on MK-801-induced learning and memory impairment in the same tests. In the PA test, either pre-training (3 and 10mg/kg, p.o.) or post-training (0.3mg/kg, i.v.) administration of lurasidone significantly reversed the test response impaired by MK-801, consistent with our previous reports. Pre-training administration of either SB-656104-A (10 and 30 mg/kg, i.p.) or WAY-100635 (1mg/kg, s.c.) also significantly reversed MK-801-induced memory impairment. Furthermore, post-training administration of either SB-656104-A (0.3mg/kg, i.v.) or WAY-100635 (0.01 mg/kg, i.v.) counteracted the effect of MK-801, which suggested that both 5-HT receptor subtype-selective antagonists could restore the memory consolidation process. In the MWM test, SB-656104-A (3mg/kg, i.p.) reversed learning impairment induced by MK-801. On the other hand, WAY-100635 (0.3 and 1mg/kg, i.p.) did not have any effect on the MK-801-induced learning impairment. Taken together, our results showed that 5-HT(7) and 5-HT(1A) receptor antagonists mimic the effect of lurasidone in whole or in part, respectively, to reverse MK-801-induced learning and memory impairment, which warrants further investigation of the interaction of lurasidone with these serotonin receptors as a possible mechanism underlying its procognitive effects in these animal models.

Single-center outcome of laparoscopic unilateral adrenalectomy for patients with primary aldosteronism: lateralizing disease using results of adrenal venous sampling.

OBJECTIVES: To assess the clinical effect of the universal use of adrenal venous sampling and to investigate the characteristics of patients with primary aldosteronism undergoing laparoscopic adrenalectomy at a single tertiary care center. METHODS: After the screening examination, confirmatory test, and computed tomography (CT) scans were completed, all patients with biochemically diagnosed hyperaldosteronism underwent adrenal venous sampling to differentiate unilateral disease from bilateral idiopathic hyperaldosteronism. A total of 174 consecutive patients with unilateral aldosterone excess underwent unilateral laparoscopic adrenalectomy. RESULTS: The surgically treated cohort was divided into 3 groups according to the CT findings. A total of 129 patients (74.1%) had findings associated with CT-positive macroadenoma (type 1A) and 42 (24.1%) with CT-negative microadenoma (type 2A). Only 3 patients (1.8%) had adrenocortical hyperplasia (type 3). The aldosterone level was normalized in all but 2 patients (98.9%), and the number of antihypertensive agents was significantly reduced within 1 month after adrenalectomy. Of the 174 patients, 155 (89.1%) showed resolution or improvement of hypertension. CONCLUSIONS: The routine use of adrenal venous sampling could adequately detect lateralization in patients with unilateral aldosterone excess, which led to satisfactory short-term outcomes after surgery. The results of the present study showed that nearly one fourth of patients with the unilateral form had a CT-negative aldosterone-producing microadenoma.

Pharmacological profile of lurasidone, a novel antipsychotic agent with potent 5-hydroxytryptamine 7 (5-HT7) and 5-HT1A receptor activity.

Lurasidone [(3aR,4S,7R,7aS)-2-[(1R,2R)-2-[4-(1,2-benzisothiazol-3-yl)piperazin-1-ylmethyl]cyclohexylmethyl]hexahydro-4,7-methano-2H-isoindole-1,3-dione hydrochloride; SM-13496] is an azapirone derivative and a novel antipsychotic candidate. The objective of the current studies was to investigate the in vitro and in vivo pharmacological properties of lurasidone. Receptor binding affinities of lurasidone and several antipsychotic drugs were tested under comparable assay conditions using cloned human receptors or membrane fractions prepared from animal tissue. Lurasidone was found to have potent binding affinity for dopamine D(2), 5-hydroxytryptamine 2A (5-HT(2A)), 5-HT(7), 5-HT(1A), and noradrenaline alpha(2C) receptors. Affinity for noradrenaline alpha(1), alpha(2A), and 5-HT(2C) receptors was weak, whereas affinity for histamine H(1) and muscarinic acetylcholine receptors was negligible. In vitro functional assays demonstrated that lurasidone acts as an antagonist at D(2) and 5-HT(7) receptors and as a partial agonist at the 5-HT(1A) receptor subtype. Lurasidone showed potent effects predictive of antipsychotic activity, such as inhibition of methamphetamine-induced hyperactivity and apomorphine-induced stereotyped behavior in rats, similar to other antipsychotics. Furthermore, lurasidone had only weak extrapyramidal effects in rodent models. In animal models of anxiety disorders and depression, treatment with lurasidone was associated with significant improvement. Lurasidone showed a preferential effect on the frontal cortex (versus striatum) in increasing dopamine turnover. Anti-alpha(1)-noradrenergic, anticholinergic, and central nervous system (CNS) depressant actions of lurasidone were also very weak. These results demonstrate that lurasidone possesses antipsychotic activity and antidepressant- or anxiolytic-like effects with potentially reduced liability for extrapyramidal and CNS depressant side effects.

Radiation dose and radiation protection for patients and physicians during interventional procedure.

Although the wide acceptance of interventional radiology (IVR) procedures has led to increasing numbers of interventions being performed, the radiation doses from IVR are higher. Increasing numbers of case reports of patient radiation injury resulting from IVR are being published. Therefore, radiation protection during IVR poses a very important problem. To protect against radiation injury, the evaluation of radiation dose is essential. The radiation dose must be evaluated for each IVR x-ray machine and each laboratory, because it varies greatly. To obtain this information easily, and to ensure practical use of the radiation information, good relationships between interventionists and medical physicists are essential.

Digital mammographic screening in Japan.

We describe the current status of mammographic screening and investigate how digital mammography is used in screening in Japan. Despite the widespread use of digital mammographic equipment, the mammographic screening rate for invited women is very low. In the majority of cases, digital hard copy images are read for screening. Soft-copy reading of digital mammography is not widely used, because of the difficulty of handling large amounts of CR data, the cost of workstations with 5 M LCD monitors, and the loading of full-field digital mammography on the mobile unit. Digital mammography has a number of advantages and has increasingly replaced conventional film-screen mammography, becoming the gold standard in combination with soft-copy reading in screening settings.

Optimizing patient radiation dose in intervention procedures.

Although numerous patients derive great benefit from interventional procedures, a serious disadvantage associated with interventional procedures is patient radiation dose. Therefore, interventionalists should be aware of how to reduce the radiation dose to their patients. Currently, no conclusive method for reducing radiation dose is available for interventional procedures; hence, it is necessary to combine various methods. In addition, in order to reduce the radiation injury risk in interventional procedures, evaluation of patient radiation dose is essential. Generally, the tradeoff for a decrease in radiation dose is a loss in image performance. Therefore, optimization of radiation dose and image performance is important in interventional procedures.

Radiation dose of interventional radiology system using a flat-panel detector.

OBJECTIVE: Currently, cardiac interventional radiology equipment has tended toward using flat-panel detectors (FPDs) instead of image intensifiers (IIs) because FPDs offer better imaging performance. However, the radiation dose from an FPD in cardiac interventional radiology is not clear. The purpose of our study was to measure the radiation doses during cineangiography and fluoroscopy of many cardiac radiology systems that use FPDs or IIs, in clinical settings. MATERIALS AND METHODS: This study examined 20 radiology systems in 15 cardiac catheterization laboratories (11 used FPD and nine used II). The entrance surface doses with digital cineangiography and fluoroscopy were compared for the 20 systems using acrylic plates (20-cm thick) and a skin dose monitor. RESULTS: For fluoroscopy, the average entrance surface doses of the 20-cm-thick acrylic plates were identical for FPD (average +/- SD, 16.63 +/- 7.89 mGy/min; range, 5.7-26.4 mGy/min; maximum/minimum, 4.63) and II (17.81 +/- 12.52 mGy/min; range, 6.5-42.2 mGy/min; maximum/minimum, 6.49) (p = 0.799). For digital cineangiography, the average entrance surface dose of the 20-cm-thick acrylic plate was slightly lower with FPD (29.68 +/- 16.40 mGy/10 s; range, 8.9-58.5 mGy/10 s; maximum/minimum, 6.57) than with II (38.50 +/- 33.71 mGy/10 s; range, 15.2-117.1 mGy/10 s; maximum/minimum, 7.70), although the difference was not significant (p = 0.487). CONCLUSION: We found that the average entrance doses of cineangiography and fluoroscopy in FPD systems were not significantly different from those in II systems. Hence, FPDs did not inherently reduce the radiation dose, although FPDs possess good detective quantum efficiency. Therefore, to reduce the radiation dose of cardiac interventional radiology systems, even FPD systems, practical measures are necessary.