Usefulness of brain SPECT to evaluate brain tolerance and hemodynamic changes during temporary balloon occlusion test and after permanent carotid occlusion.

UNLABELLED: The purpose of this study was to evaluate the usefulness of SPECT during temporary carotid balloon occlusion testing and to evaluate the changes in regional cerebral blood flow (CBF) and regional cerebral perfusion reserve (CPR) after permanent carotid occlusion. METHODS: Temporary balloon occlusion testing was performed on 40 patients (24 head and neck tumors, 16 aneurysms). During the balloon occlusion (total time, 30 min), (99m)Tc-ethylcysteinate dimer (ECD) was injected intravenously about 5 min before balloon deflation, followed by SPECT data acquisition. SPECT images were visually evaluated, and the severity of hypoperfusion on the occluded side was classified using 4 grades (normal, mild, moderate, and severe). The count ratio of the occluded side to the contralateral side (L/N ratio) was also analyzed. In 7 patients who subsequently underwent permanent carotid occlusion, CBF and CPR were quantitatively assessed using (133)Xe inhalation dynamic SPECT at rest and after acetazolamide (ACZ) enhancement (CPR was defined as the percentage increase in CBF after ACZ), and the patients were followed up periodically. RESULTS: SPECT after temporary occlusion showed moderate or severe hypoperfusion in 12 patients, whereas neurologic deterioration was observed in only 4 patients. The L/N ratios were 0.96 +/- 0.03 in normal perfusion (13 patients), 0.93 +/- 0.03 in mild hypoperfusion (15 patients), 0.83 +/- 0.03 in moderate hypoperfusion (10 patients) and 0.66 +/- 0.09 in severe hypoperfusion (2 patients) (P < 0.0001). In the 7 patients who underwent permanent carotid occlusion, CPR decreased after surgery (35% +/- 7% vs. 7% +/- 14%, P < 0.05), even though the resting CBF did not change (54 +/- 8 mL/100 g/min vs. 52 +/- 6 mL/100 g/min, not statistically significant). The steal phenomenon (rCPR < 0%) was observed in 3 patients, 1 of whom experienced transient hemiparesis when blood pressure dropped soon after surgery. On follow-up, the decreased CPR gradually improved and no infarction developed. CONCLUSION: SPECT is useful to detect cerebral hypoperfusion during carotid occlusion. Assessment of CPR is recommended to predict the potential risk of postsurgical complications and to follow up patients after permanent carotid occlusion.

Measurement of localized ground-glass attenuation on thin-section computed tomography images: correlation with the progression of bronchioloalveolar carcinoma of the lung.

RATIONALE AND OBJECTIVE: This study was to measure localized ground-glass attenuation (GGA) in the peripheral lung on thin-section computed tomography (CT) and to assess any relationship between the attenuation and lesion. MATERIALS AND METHODS: Twenty-eight surgically resected tumors with localized GGA at thin-section CT were studied. The tumors were histologically diagnosed as 8 atypical adenomatous hyperplasia (AAH), 11 bronchioloalveolar carcinoma (BAC), and 9 BAC with fibrosis. We assumed three concentric circles, which were 0.8, 1.0, and 1.2 times the diameter of each tumor and measured the average CT values corresponding to inside each circle. We calculated a difference in CT value between 0.8 and 1.2 times the diameter of the tumor and defined as the contrast index. RESULTS: The contrast index for tumors with AAH, BAC, and BAC with fibrosis were 19.8 +/- 8.3, 42.5 +/- 16.0 (P < 0.05 vs. group with AAH), and 111.4 +/- 32.6 (P < 0.0001 vs. Group with BAC), respectively. The contrast index became greater in the stepwise progression from AAH to BAC and from BAC to BAC with fibrosis. CONCLUSION: The contrast index correlated histologic findings of the tumor growth in BAC. The contrast index may be a useful and objective measurement for determining surgical treatment for localized GGA in preoperative diagnosis.

Pulsating renal blood flow distribution measured using power Doppler ultrasound: correlation with hypertension.

Arterial compliance is associated with the first stage of hypertension and atherosclerosis. We propose here a compliance index, which measures pulsating renal blood flow distribution using a power Doppler ultrasound (US). We assessed the relationship between the compliance index and blood pressure and between the compliance index and risk factors of atherosclerosis. The subjects consisted of 136 consecutive patients (96 males, 40 females) who underwent a physical checkup. Ages ranged from 40 to 60 years with a mean of 50.1 years. Patients with past renal disease and/or renal dysfunction were excluded. Using a power Doppler US combined with an ECG-gated and echo-tracking system, we recorded the vascular distribution of the renal parenchyma at 8 to 10 time points during an interval of the R wave of the ECG. Using a color pixel counting technique, we calculated the area (A) corresponding to the colored vascular distribution at power Doppler US. The relationships between A and the time points (t) were fitted to a quadratic equation. The compliance index of renal parenchymal vessels was obtained by twice differentiating the quadratic equation obtained above (d2A/dt2), and taking the result as a new hemodynamic index. In the univariate correlation analysis, the compliance index was correlated with age (r=-0.26, p=0.002), systolic blood pressure (r=-0.33, p=0.0001), diastolic blood pressure (r=-0.45, p<0.0001), serum uric acid (r=-0.28, p=0.001), and body mass index (r=-0.32, p=0.0002). On the multivariate stepwise regression analysis, the compliance index was significantly correlated with diastolic blood pressure (beta=-0.36, p<0.0001) and body mass index (beta=-0.18, p<0.0001). In conclusion, the compliance index is a candidate for a new hemodynamic marker of renal blood flow abnormality caused by hypertension.

Renal uptake rate measurement of 99m Tc-dimercaptosuccinic acid using spectral analysis.

We developed a new method for measuring the rate of renal uptake of 99mTc-dimercaptosuccinic acid (DMSA) using spectral analysis. The renal uptake rate (per minute) of DMSA (K) was calculated by averaging the tissue impulse response function values obtained by spectral analysis between 10 min and 15 min. The K values obtained by spectral analysis correlated well with the renal uptake rates (%) measured 2h after DMSA administration (r=0.921 with background correction; r=0.924 without background correction). There was a good agreement between the K values obtained by spectral analysis using the kidney time-activity curves with (x) and without (y) background correction (r=0.993, y=1.089x+0.004), suggesting that our method requires no background correction. There was excellent correlation between the K values obtained by spectral analysis using the kidney time-activity curves with (y) and without (x) kidney depth correction (r=0.992, y=1.721x+0.000 with background correction; r=0.990, y=1.720x+0.000 without background correction), suggesting that our method requires no kidney depth correction. These results indicate that spectral analysis is appropriate and useful for the quantification of renal uptake rate of DMSA. We believe that this method will facilitate even more widespread utilization of the quantitative assessment of DMSA uptake by planar scintigraphy, since it needs only 10-15 min for imaging, and background and kidney depth correction and blood sampling are not required.

In vitro evaluation of normal and abnormal lungs with ultra-high-resolution CT.

Synchrotron radiation microtomography is a new technique with high directionality of a synchrotron radiation beam and a high-resolution detector array. In this study, we estimated the visualization of the peripheral human lung structure with an ultra-high-resolution computed tomography (CT) system, the synchrotron radiation CT. The synchrotron radiation CT system uses the bending magnet beamline emitted from the 8.0 GeV electron storage ring. Six lung specimens were obtained at autopsy: 3 normal, 1 cellular alveolitis, 1 diffuse alveolar damage, and 1 pulmonary hemorrhage. Each specimen was cut down to a cylindrical sample with 6-mm diameter and 15- to 25-mm height. The synchrotron radiation CT images of these lung samples were obtained using the ultra-high-resolution image detector system with a charge coupled device (CCD) array detector (1024 x 1024 pixels with 12 x 12 microm2 pixel size). After that, the sample specimens were sliced to 200 microm (micrometer) thickness, and were observed with a stereomicroscope and by contact radiography. Finally, approximately 10-microm thick microscopic images were obtained and compared with the synchrotron radiation CT images. The synchrotron radiation CT could depict the peripheral lung including peripheral airways, airspaces, and alveolar walls individually. Each finding in the 3 disease processes seen on the synchrotron radiation CT images correlated well with the microscopic findings. The synchrotron radiation CT allows microtomographic imaging of human lung specimens with ultra high-spatial resolution (12 microm) on a level approaching that of conventional histopathology, without sectioning.

Humidifier lung: possible contribution of endotoxin-induced lung injury.

A 56-year-old man was admitted with cough, fever, myalgia, and arthralgia. Chest computed tomography demonstrated bilateral diffuse ground-glass opacities predominantly in the upper lungs. Subpleural non-segmental consolidation was observed in the late phase. Hypersensitivity pneumonitis was suspected, and an environmental provocation test with the incidental use of a home ultrasonic humidifier was positive. Unlike typical hypersensitivity pneumonitis, serum KL-6 levels were normal. Although several microorganisms were isolated from the humidifier water, there was no evidence for immune sensitization. We detected high amounts of endotoxin in the humidifier water, which may have contributed to the lung injury of this patient.

Ischemic "memory image" in acute myocardial infarction of 123I-BMIPP after reperfusion therapy: a comparison with 99mTc-pyrophosphate and 201Tl dual-isotope SPECT.

Ischemic "memory image" is a phenomenon of 123I-15-(p-iodophenyl)-3-(R,S)-methylpentadecanoic acid (BMIPP) in which an area at risk of acute myocardial infarction (AMI), could be detected as a defect in a couple of weeks even after successful reperfusion therapy. The purpose of this study was to clarify the incidence of the ischemic "memory image" of 123I-BMIPP in patients with AMI by comparing 99mTc-PYP and 201Tl dual-isotope SPECT. Materials consisted of 14 patients with successfully reperfused AMI and 20 patients with old myocardial infarction (OMI). All AMI patients underwent PYP/Tl dual-isotope SPECT within 1 week after the onset of AMI, and BMIPP SPECT was performed within 1 week after the PYP/Tl dual-isotope SPECT. The extent and severity of the defect of BMIPP and Tl were visually scored into four grades: 0 = no defect to 3 = large or severe defect. These scores were compared. PYP positive AMI lesions were concordant with BMIPP defects (13/14). In AMI, both the extent and severity scores of BMIPP were higher than 201Tl (p < 0.001). Differences (BMIPP - Tl) of extent and severity scores were greater in AMI than in OMI (p < 0.001). In conclusion, the ischemic "memory image" obtained by means of the BMIPP is a common phenomenon (13/14) in AMI, and helpful in evaluating the area at risk.

Clinical usefulness of the cardiac multi-detector-row CT.

Along with improvement of the temporal and special resolution, multi-detector-row CT has become able to generate artifact-less heart images. We discuss the potential benefits of the newly developed cardiac application, demonstrating informative cases.Two- and three-dimensional (2D and 3D) cardiac images were produced throughout one cardiac cycle. By paging 2D and 3D images in cardiac cycle order, animated movies were generated. Cardiac imaging with multi-detector-row CT, acquired during a single breath hold, provides information about: (1) clear morphology of heart chambers and myocardium, (2) wall motion and systolic thickening, (3) myocardial perfusion, (4) volume assessment, and (5) coronary anatomy and pathophysiology.

Intravenous three-dimensional CT portography using multi-detector row CT in patients with hepatic cirrhosis: evaluation of scan timing and image quality.

PURPOSE: To evaluate the scan timing and image quality of intravenous three-dimensional (3D) CT portography using multi-detector row CT (MDCT) and to assess the influence of patients' body weight on enhancement of the portal vein (PV). METHODS: One hundred nine patients with hepatic cirrhosis underwent triple-phase contrast enhanced CT using MDCT. The early, portal, and late phases were started at 30 sec, 60 sec, and 90 sec, respectively, after the beginning of intravenous injection of contrast medium (300 mgI/mL, 100 mL total). The CT value of the PV was assessed in the three phases: precontrast, portal phase, and late phase. 3D-portography of the MIP image was evaluated by three-point scale based on vessel visualization. The relationship between these data and body weight was investigated. RESULTS: The mean CT value of PV at 60 sec was 172.01+/-25.94 HU, which was significantly higher than that at 90 sec. Good or excellent 3D-CT portography was obtained in 97/109 patients (89%). Heavy patients tended to show less opacification of PV. CONCLUSIONS: Intravenous 3D-CT portography using MDCT at a 60 sec delay provided adequate PV images for patients with hepatic cirrhosis. Enhancement of PV was affected by patients' body weight.

Effect of temporal subtraction technique on the diagnosis of primary lung cancer with chest radiography.

PURPOSE: The purpose of this study was to assess the diagnostic accuracy of the temporal subtraction technique in the detection of primary lung cancers by readers with different levels of experience. METHODS: Previous and current chest radiographs from 40 patients with histologically proven lung cancer and 40 controls were studied. Temporal subtraction images were produced using an automated digital subtraction technique. We evaluated the effect of temporal subtraction images in the diagnosis of lung cancer with chest radiographs via an observer performance study with the use of receiver operating characteristic analysis. Six experienced radiologists and six residents participated as observers. RESULTS: Observer performance for all observers was superior when temporal subtraction images were used (mean Az value increased from 0.764 to 0.836, p=0.0006). Although the average Az value for residents increased significantly, from 0.707 to 0.795 (p=0.0038), the average Az value for experienced radiologists increased only from 0.821 to 0.878 (n.s.). CONCLUSION: In conclusion, the temporal subtraction technique clearly improves diagnostic accuracy for the detection of primary lung cancer. The results indicated that the use of temporal subtraction images was more beneficial for the residents than for the experienced radiologists. This method would compensate to some extent for experience-dependent diagnostic accuracy in the detection of lung cancer.

Pulmonary lesions detected in population-based CT screening for lung cancer: reliable findings of benign lesions.

PURPOSE: To identify the characteristics of benign pulmonary lesions in order to reduce false-positive rates in screening computed tomography (CT) and in order to reduce frequency of follow-up high-resolution CT (HRCT). MATERIALS AND METHODS: We evaluated 238 screening-detected benign lesions and 23 screening-detected lung cancers for 12 characteristics: spiculation, well-defined margin, concave margin, polygonal shape, notch/lobulation, solid component, ground-glass opacity (GGO), air bronchogram, cavity, bubble-like appearance, pleural indentation, and vascular convergence. We also measured the lesion diameters to set a threshold for benign lesions. We tested combinations of these characteristics to differentiate benign lesions from lung cancers. RESULTS: By using certain combinations of the characteristics that showed statistically significant differences between benign lesions and lung cancers, benign lesions could be extracted without contamination by lung cancer in screening CT, when the combination included solid component as a positive finding. In HRCT, more than 80% of the benign lesions could be extracted without contamination by lung cancer when the combination included GGO as a negative finding. CONCLUSION: It seems possible to reduce the frequency of follow-up HRCT to establish a diagnosis of benign lesions using certain combinations of the characteristics of benign nodules.

Assessment of left ventricular volumes using multi-detector row computed tomography (MDCT): phantom and human studies.

PURPOSE: Multi-detector row CT (MDCT) is a new noninvasive modality for coronary artery imaging. Using the same MDCT data obtained for coronary artery assessment, left ventricular (LV) volumes such as end-diastolic (ED) and end-systolic (ES) volumes (EDV and ESV, respectively) and ejection fraction (EF) can potentially be assessed when ED and ES datasets are extracted. The purpose of this study was to evaluate the feasibility of MDCT in the assessment of LV volumes. METHODS: Using a pulsating heart phantom (EDV = 143 ml, ESV = 107 ml, stroke volume = 36 ml, EF = 25%) and MDCT, EDV and ESV were measured and EF was calculated. Clinical materials consisted of 11 consecutive human subjects who underwent MDCT. MDCT data were acquired during a single breathhold, using an intravenous injection of contrast medium. Left ventriculography (LVG) was performed in all patients as a gold standard. LV-EF was calculated by measuring ESV and EDV in all patients. RESULTS: In the phantom study, LV volumes were: EDV = 137 ml, ESV = 101 ml, stroke volume = 36 ml, and EF = 26%. Close correlations were observed between MDCT values and LVG values (EDV: r = 0.95, ESV: r = 0.98, EF: r = 0.93, p < 0.001). CONCLUSION: MDCT was useful for th e assessment of LV volumes and EF in various patients with CVD.

Usefulness of turbo-fluid-attenuated inversion-reovery (tFLAIR) sequence in diagnosing meningioma.

PURPOSE: We evaluated qualitatively and quantitatively the usefulness of turbo-FLAIR (tFLAIR) in diagnosing meningioma in comparison with the T2-weighted turbo spin echo (T2W-TSE) sequence. MATERIALS AND METHODS: Forty-eight patients diagnosed with meningioma were studied. In the qualitative study, we evaluated tumor delineation, contrast (Co) of tumor-to-CSF (cerebrospinal fluid), Co of tumor-to-brain parenchyma, Co of peripheral edema-to-brain parenchyma, and detectability of tumor margin. In quantitative study-1, using signal intensity (SI), we measured SI and calculated Co-SI of tumor-to-gray matter, Co-SI of tumor-to-white matter, Co-SI of peripheral edema-to-white matter, and Co-SI of tumor-to-CSF. In quantitative study-2, using film density, we measured density (De) on hard-copy film images and calculated Co-De for the same items as in quantitative study-1. RESULTS: In the qualitative study, tFLAIR was superior to T2W-TSE in tumor delineation, Co of tumor-to-CSF, Co of tumor-to-brain parenchyma, and Co of peripheral edema-to-brain parenchyma. In quantitative study-1, tFLAIR was superior to T2W-TSE in Co-SI of tumor-to-CSF, however, T2W-TSE was superior to tFLAIR in Co-SI of tumor-to-white matter. In quantitative study-2, tFLAIR was superior to T2W-TSE in all Co-De. CONCLUSION: tFLAIR was superior to T2W-TSE in the depiction of meningioma.

Remitting seronegative symmetric synovitis with pitting edema: scintigraphic and magnetic resonance imaging findings.

Remitting seronegative symmetric synovitis with pitting edema (RS3PE) was first reported by McCarty et al in 1985 and refers to a rheumatologic set of symptoms with acute onset, with no erosive bone lesions, with seronegative findings, affecting the elderly more frequently, and showing an excellent prognosis with low-dose steroid therapy. Although these characteristics make it possible to differentiate it from rheumatoid arthritis and rheumatic polymyalgia, there have been very few reports on the imaging findings. The authors present scintigraphic and magnetic resonance images in a case of RS3PE.

Survival prediction using artificial neural networks in patients with uterine cervical cancer treated by radiation therapy alone.

BACKGROUND: We evaluated the usefulness of artificial neural networks (ANNs) for survival prediction in patients with uterine cervical cancer treated by radiotherapy. METHODS: We used data from 134 patients with uterine cervical cancer treated by combined external and high-dose-rate remote afterloading intracavitary radiotherapy between 1978 and 1993. The ANNs were trained using the data from 67 randomly selected patients. Using the trained ANNs, we predicted the 5-year survival in the remaining 67 patients, and compared it with the known 5-year survival. The performance of the ANNs was evaluated using a receiver operating characteristic (ROC) curve and was compared using the area under the ROC curve (Az). RESULTS: When fundamental factors, such as age, performance status, hemoglobin, total protein, International Federation of Gynecology and Obstetrics (FIGO) stage, and histological type were used as inputs in the ANNs, Az was 0.5483 +/- 0.0145 (mean +/- SD). When the histological grading of radiation effect determined by periodic biopsy examination was used in addition to the fundamental factors, Az was highest (0.7782 +/- 0.0105). When the cytological grading of radiation effect by the periodic smear was used in addition to the fundamental factors, Az was 0.5523 +/- 0.0135, which was not significantly different from that when only the fundamental factors were used. CONCLUSION: ANNs allow us to evaluate the importance of prognostic factors, and make it possible to predict the survival of each patient. Using ANNs, the combination of histological grading of radiation effect determined by periodic biopsy examination, in addition to the fundamental factors, is the most effective for prediction of survival in patients with uterine cervical cancer.

Quantitative evaluation of mean transit times obtained with dynamic susceptibility contrast-enhanced MR imaging and with (133)Xe SPECT in occlusive cerebrovascular disease.

OBJECTIVE: We report on quantitative mean transit time images obtained using dynamic susceptibility contrast-enhanced MR imaging after an IV bolus injection of a contrast agent. Our study compared cerebral hemodynamics measured using dynamic susceptibility contrast-enhanced MR imaging with the cerebral perfusion reserve obtained using dynamic (133)Xe single-photon emission computed tomography (SPECT). SUBJECTS AND METHODS: Seventeen patients with chronic cerebral artery occlusion or stenosis diagnosed by digital subtraction angiography were examined. Dynamic susceptibility contrast-enhanced MR imaging data were acquired using a multishot echoplanar sequence. Our procedure for quantification of mean transit time was based on the indicator dilution theory and deconvolution analysis. RESULTS: The increased mean transit time values obtained with dynamic susceptibility contrast-enhanced MR imaging correlated well (r=-0.789, p < 0.0001) with decreased cerebral perfusion reserve determined by performing dynamic (133)Xe SPECT before and after administration of acetazolamide. The mean transit time values in the regions with severely decreased perfusion reserve were significantly higher than those in the regions with normal or moderately decreased perfusion reserve (p < 0.0001 and p = 0.0004, respectively). CONCLUSION: Mean transit time images generated from dynamic susceptibility contrast-enhanced MR imaging data could be used to evaluate the extent of cerebral perfusion reserve impairment in patients with occlusive cerebrovascular disease.

Using the World Health Organization Classification of thymic epithelial neoplasms to describe CT findings.

OBJECTIVE: Our purpose was to assess the CT features of various subtypes of thymic epithelial neoplasms on the basis of the 1999 World Health Organization classification. MATERIALS AND METHODS: Thymic epithelial neoplasms in 53 patients who underwent thymectomy were retrospectively assessed histologically according to the 1999 World Health Organization classification. Type A and B neoplasms correspond to thymomas and type C, to thymic carcinoma. The study included four patients with type A, 14 with type AB, nine with type B1, 14 with type B2, four with type B3, and eight with type C epithelial tumors. Two observers independently assessed the CT scans without knowledge of the histologic findings. RESULTS: Type A tumors were more likely to have smooth contours on CT (4/4, 100%) and round shapes (3.5/4, 88%) than any other type of thymic epithelial tumor (all, p < 0.05). Type C tumors had a higher prevalence of irregular contours (6/8, 75%) than any other type of thymic epithelial tumor (all, p < 0.05). Calcification was more frequently seen in type B1 (4/9, 44%), type B2 (8.5/14, 61%), and type B3 (3/4, 75%) tumors than in type AB (2/14, 14%) and type C (0.5/8, 6%) tumors (all, p < 0.05). CONCLUSION: Smooth contours and a round shape are most suggestive of type A thymic epithelial tumor, whereas irregular contours are most suggestive of type C tumor. Calcification is suggestive of type B tumors. CT is of limited value, however, in differentiating type AB, B1, B2, and B3 tumors.