Evaluation of the accuracy of heart dose prediction by machine learning for selecting patients not requiring deep inspiration breath‑hold radiotherapy after breast cancer surgery

Increased heart dose during postoperative radiotherapy (RT) for left-sided breast cancer (BC) can cause cardiac injury, which can decrease patient survival. The deep inspiration breath-hold technique (DIBH) is becoming increasingly common for reducing the mean heart dose (MHD) in patients with left-sided BC. However, treatment planning and DIBH for RT are laborious, time-consuming and costly for patients and RT staff. In addition, the proportion of patients with left BC with low MHD is considerably higher among Asian women, mainly due to their smaller breast volume compared with that in Western countries. The present study aimed to determine the optimal machine learning (ML) model for predicting the MHD after RT to pre-select patients with low MHD who will not require DIBH prior to RT planning. In total, 562 patients with BC who received postoperative RT were randomly divided into the trainval (n=449) and external (n=113) test datasets for ML using Python (version 3.8). Imbalanced data were corrected using synthetic minority oversampling with Gaussian noise. Specifically, right-left, tumor site, chest wall thickness, irradiation method, body mass index and separation were the six explanatory variables used for ML, with four supervised ML algorithms used. Using the optimal value of hyperparameter tuning with root mean squared error (RMSE) as an indicator for the internal test data, the model yielding the best F2 score evaluation was selected for final validation using the external test data. The predictive ability of MHD for true MHD after RT was the highest among all algorithms for the deep neural network, with a RMSE of 77.4, F2 score of 0.80 and area under the curve-receiver operating characteristic of 0.88, for a cut-off value of 300 cGy. The present study suggested that ML can be used to pre-select female Asian patients with low MHD who do not require DIBH for the postoperative RT of BC.

Mean Heart Dose Prediction Using Parameters of Single-Slice Computed Tomography and Body Mass Index: Machine Learning Approach for Radiotherapy of Left-Sided Breast Cancer of Asian Patients

Deep inspiration breath-hold (DIBH) is an excellent technique to reduce the incidental radiation received by the heart during radiotherapy in patients with breast cancer. However, DIBH is costly and time-consuming for patients and radiotherapy staff. In Asian countries, the use of DIBH is restricted due to the limited number of patients with a high mean heart dose (MHD) and the shortage of radiotherapy personnel and equipment compared to that in the USA. This study aimed to develop, evaluate, and compare the performance of ten machine learning algorithms for predicting MHD using a patient's body mass index and single-slice CT parameters to identify patients who may not require DIBH. Machine learning models were built and tested using a dataset containing 207 patients with left-sided breast cancer who were treated with field-in-field radiotherapy with free breathing. The average MHD was 251 cGy. Stratified repeated four-fold cross-validation was used to build models using 165 training data. The models were compared internally using their average performance metrics: F2 score, AUC, recall, accuracy, Cohen's kappa, and Matthews correlation coefficient. The final performance evaluation for each model was further externally analyzed using 42 unseen test data. The performance of each model was evaluated as a binary classifier by setting the cut-off value of MHD ≥ 300 cGy. The deep neural network (DNN) achieved the highest F2 score (78.9%). Most models successfully classified all patients with high MHD as true positive. This study indicates that the ten models, especially the DNN, might have the potential to identify patients who may not require DIBH.

Evaluation of calculation processes of apparent diffusion coefficient subtraction method (ASM) imaging

A number of restricted diffusion (RD) imaging techniques, such as diffusion kurtosis (DK) imaging and Q space imaging, have been developed and proven to be useful for the diagnosis of diseases, including cerebral gliomas and cerebrovascular infarction. In particular, apparent diffusion coefficient (ADC) subtraction method (ASM) imaging has become available recently as a novel RD imaging technique. ASM is based on the difference between the ADC values in an image pair of two ADC maps, ADC basic (ADCb) and ADC modify (ADCm), which are created from diffusion-weighted images taken using short and long effective diffusion times, respectively. The present study aimed to assess the potential of different types of ASM imaging by comparing them with DK imaging which is the gold-standard RD imaging technique. In the present basic study using both polyethylene glycol phantom and cell-containing bio-phantom, three different types of ASM images were created using different calculation processes. ASM/A is an image calculated by dividing the absolute difference between ADCb and ADCm by ADCb several times. By contrast, ASM/S is an image created by dividing the absolute difference between ADCb and ADCm by the standard deviation of ADCb several times. As for positive ASM/A image (PASM/A), the positive image, which was resultant after subtracting ADCb from ADCm, was divided by ADCb several times. A comparison was made between the types of ASM and DK images. The results showed the same tendency between ASM/A in addition to both ASM/S and PASM/A. By increasing the number of divisions by ADCb from three to five times, ASM/A images transformed from DK-mimicking to more RD-sensitive images compared with DK images. These observations suggest that ASM/A images may prove useful for future clinical applications in RD imaging protocols for the diagnosis of diseases.

Evaluation of Fast Diffusion Kurtosis Imaging Using New Software Designed for Widespread Clinical Use

Clinical research using restricted diffusion-weighted imaging, especially diffusion kurtosis (DK) imaging, has been progressing, with reports on its effectiveness in the diagnostic imaging of cerebral infarctions, neurodegenerative diseases, and tumors, among others. However, the application of DK imaging in daily clinical practice has not spread because of the long imaging time required and the use of specific software for image creation. Herein, with the aim of promoting clinical research using DK imaging at any medical facility, we evaluated fast DK imaging using a new software program. We developed a new macro program that produces DK images using general-purpose, inexpensive software (Microsoft Excel and ImageJ), and we evaluated fast DK imaging using bio-phantoms and a healthy volunteer in clinical trials. The DK images created by the new software with diffusion-weighted images captured with short-time imaging sequences were similar to the original DK images captured with long-time imaging sequences. The DK images using three b-values, which can reduce the imaging time by 43%, were equivalent to the DK images using five b-values. The DK imaging technique developed herein might allow any medical facility to increase its daily clinical use of DK imaging and easily conduct clinical research.

Development and Evaluation of a Short-time Imaging Method for the Clinical Study of the Apparent Diffusion Coefficient Subtraction Method

The apparent diffusion coefficient subtraction method (ASM) was developed as a new restricted diffusionweighted imaging technique for magnetic resonance imaging (MRI). The usefulness of the ASM has been established by in vitro basic research using a bio-phantom, and clinical research on the application of the ASM for the human body is needed. Herein, we developed a short-time sequence for ASM imaging of the heads of healthy volunteers (n=2), and we investigated the similarity between the obtained ASM images and diffusion kurtosis (DK) images to determine the utility of the ASM for clinical uses. This study appears to be the first to report ASM images of the human head. We observed that the short-time sequence for the ASM imaging of the head can be scanned in approx. 3 min at 1.5T MRI. The noise reduction effect of median filter processing was confirmed on the ASM images scanned by this sequence. The obtained ASM images showed a weak correlation with the DK images, indicating that the ASM images are restricted diffusion-weighted images. The new shorttime imaging sequence could thus be used in clinical studies applying the ASM.

New field-in-field with two reference points method for whole breast radiotherapy: Dosimetric analysis and radiation-induced skin toxicities assessment

The usefulness of the field-in-field with two reference points (FIF w/ 2RP) method, in which the dose reference points are set simultaneously at two positions in the irradiation field and the high-dose range is completely eliminated, was examined in the present study with the aim of decreasing acute skin toxicity in adjuvant breast radiotherapy (RT). A total of 573 patients with breast cancer who underwent postoperative whole breast RT were classified into 178 cases with wedge (W) method, 142 cases with field-in-field without 2 reference points (FIF w/o 2RP) method and 253 cases with FIF w/ 2RP method. Using the FIF w/ 2RP method, the high-dose range was the lowest among the three irradiation methods. The planning target volume (PTV) V105% and the breast PTV for evaluation (BPe) V105% decreased to 0.09 and 0.10%, respectively. The FIF w/ 2RP method vs. the FIF w/o 2RP method had a strong association (η) with PTV V105% (η=0.79; P<0.001) and BPe V105% (η=0.76; P<0.001). The FIF w/ 2RP method had a significant impact on lowering the skin toxicity grade in weeks 3 and 4, and increasing the occurrence of skin toxicity grade 0. The FIF w/ 2RP method vs. the W method had a moderate association with skin toxicity grade at week 3 (η=0.49; P<0.001). Using the FIF w/ 2RP method, the high-dose range V105% of the target decreased to 0%, and skin adverse events were decreased in conjunction. For patients with early-stage breast cancer, particularly patients with relatively small-sized breasts, the FIF w/ 2RP method may be an optimal irradiation method.

Development of a novel phantom using polyethylene glycol for the visualization of restricted diffusion in diffusion kurtosis imaging and apparent diffusion coefficient subtraction method

The present study aimed to investigate whether polyethylene glycol (PEG) phantoms have the potential to be used as standard phantoms for magnetic resonance imaging (MRI) in order to visualize restricted diffusion in diffusion kurtosis imaging (DKI), the ADC subtraction method (ASM) and the apparent diffusion coefficient (ADC). Diffusion-weighted images of 0-120 mM PEG phantoms were captured to create ADC, DKI and ASM images with post-processing. ASM is a recently developed method for restricted diffusion imaging using the readout segmentation of long variable echo-train sequences. As the PEG concentration increases, the ADC value decreases. Conversely, an increase in DKI and ASM values is associated with increasing PEG concentration. Formulae were constructed to represent the association between PEG concentrations and ADC, DKI and ASM values. These formulae can be used to determine the required PEG concentrations to mimic arbitrary ADC, DKI and ASM values of certain diseases, including tumors and infarctions. Validation experiments were conducted using bio-phantoms and clarified that the PEG phantoms cover the range of ADC and DKI values reported in previous clinical research using 3T MRI. PEG phantoms may be useful for future MRI research involving restricted diffusion.

Differential Diagnosis of Adrenal Masses Using Out-of-Phase Flash Imaging

The purpose of this report was to suggest the ability to differentiate adrenal masses by out-of-phase FLASH imaging. The images were obtained with breath-holding at TR/TE 100/12 ms, flip angle 20°. The material included adrenal adenoma (n = 16), nodular hyperplasia (n = 1), pheochromocytoma (n = 5), and adrenal metastatic tumors (n = 7). The signal intensity ratios of the adrenal mass/the diaphragmatic crus, back muscle, and renal cortex were obtained. The mean values of the ratios of adenomas or nodular hyperplasia were significantly different from pheochromocytomas or metastases. Although the number of adrenal masses was fairly small, the ratios of adrenal mass/diaphragmatic crus could distinguish them with no overlapping case. All 17 masses with the ratio of 1.16 or less were adenomas or nodular hyperplasia, whereas all 12 masses with a ratio greater than 1.23 were pheochromocytomas or metastases. This result suggests the ability of out-of-phase FLASH imaging to differentiate adrenal masses.

Short communication. Development of a fine thermocouple-needle system for real-time feedback of thermal tumour ablation margin

Thermal tumour ablation techniques such as radiofrequency (RF) ablation are applied for radical removal of local tumours as an easier, less invasive alternative to surgical resection. A serious drawback of thermal ablation, however, is that the ablation area cannot be accurately assessed during the procedure. To achieve real-time feedback and exact and safe ablation, a superfine thermocouple-needle system (TNS) comprising a 0.25-mm diameter thermocouple embedded in a 22-G, 15-cm-long needle was devised and efficacy was tested in vitro using porcine livers (n = 15) and in vivo using rabbit back muscles (n = 2) and livers (n = 3). A 17-gauge RF electrode with a 2 cm active tip was used for ablation. The TNS was inserted 1 cm from the active tip of the RF electrode and liver temperature around the electrode was measured concurrently. The RF current was cut off when the temperature reached 60°C or after 5 min at ≥50°C. Porcine livers and rabbit back muscles were then cut along a plane passing through the axes of the electrode and the TNS. In rabbit livers, contrast-enhanced CT was performed to evaluate ablation areas. Ablation areas in cut surfaces of porcine livers exhibited well-defined discoloured regions and the TNS tip precisely pinpointed the margin of the ablation area. Contrast-enhanced CT of rabbit livers showed the TNS tip accurately located at the margin of areas without contrast enhancement. These results indicate that the TNS can accurately show ablation margins and that placing the TNS tip at the intended ablation margin permits exact thermal ablation.

CT-guided radiofrequency liver tumour ablation: use of a two-step coaxial system with a fine guide needle wire unit for high-risk cases

Accurate radiofrequency (RF) needle targeting to liver lesions under CT guidance is technically difficult and generally requires multiple needle manipulations, which carries potential risk. This approach is hardly applicable for precariously located lesions or for patients who have difficulty holding their breath. The aim of this study was to develop a novel two-step coaxial system to facilitate CT-guided RF ablation in difficult cases. The study group comprised 11 patients with 12 hepatic lesions. The coaxial system consisted of two parts: a 21-gauge pencil-tip guide needle wire (GNW) unit comprising a 150-mm-long needle segment and a 250-mm-long wire segment; and a 140-mm-long outer cannula with its stylet, which accepts a 17-gauge RF electrode needle. The GNW was inserted until the route of the GNW was confirmed to be positioned correctly. The cannula with the stylet was then advanced along the GNW. Lesions were successfully accessed using the GNW, even in patients who could not hold their breath, and manipulation was feasible within the limited space of the CT gantry. The light GNW also facilitated step-by-step CT-guided angular manipulations, unlike heavy RF electrodes, which are unstable during hands-free use unless deeply inserted. Therefore, this system enabled sequential ablations of large tumours by ensuring three different routes in advance by using the GNW. Insertion of the cannula along the GNW was simple. In conclusion, the two-step coaxial system enabled CT-guided RF tumour ablation to be performed in cases conventionally contraindicated owing to high risk of serious complications.

Expansion of radiofrequency ablation volume by saturated NaCl saline injection in the area of vaporization

BACKGROUND

Vaporization around the radiofrequency (RF) electrode after RF application (RFA) limits the RF ablation area.

PURPOSE

To determine whether saturated saline injected into the area of vaporization after initial RFA extends ablation area after further RFA.

MATERIAL AND METHODS

RFA was performed in 18 ex vivo porcine livers and four in vivo rabbit erector spinae muscles. An RF electrode was used to ablate an area with 40W of parallel current for 15 min. The ablation margin was determined using a thermocouple, and the radius of the ablated area was measured. After RF electrode removal, saturated saline was infused through a percutaneous ethanol injection needle into the site of the original RFA in 11 liver samples and two erector spinae muscles. Three minutes later, RFA was resumed for 15 min. The remaining seven control liver samples and two spinae muscles received RFA without saline injection. The radius of the final ablated area was then measured.

RESULTS

In the ex vivo study, injection of saturated saline significantly decreased tissue impedance (87.7+/-9.4 to 51.1+/-9.7 Omega, P<0.0001), and increased the mean radius of the ablated area (15.9+/-3.0 to 25.0+/-3.6 mm, P<0.0001). These significant changes were not observed without injection of saturated saline. Similar trends were found in the in vivo study.

CONCLUSION

Injection of saturated saline into the area of vaporization around the RF electrode, followed by additional RFA, caused concentric expansion of the final ablation area, facilitating more efficient tumor ablation.

Pupillary abnormality on admission and brain bulging during surgery as unfavourable predictors in patients treated with hypothermia: a retrospective review of 81 patients with severe head injury

BACKGROUND

To determine factors predicting outcome of patients with severe head injury, the authors retrospectively analyzed 81 patients, 3 to 70 years of age, who were treated by hypothermia.

METHOD

The initial Glasgow Coma Scale scores of the 81 patients ranged from 3 to 8. Outcome in each case was determined at six months after injury and was retrospectively analyzed with respect to patient characteristics, initial clinical status, laboratory data, computed tomographic findings, data from monitoring, intra-operative findings, and treatment methods. The significance of clinical and neuroradiological factors for predicting unfavorable outcome was analyzed by univariate logistic regression. Stepwise multiple logistic regression analysis was then used to identify independent predictors of outcome.

FINDINGS

Favorable outcome was observed in 27 of 81 patients treated by hypothermia. Independent factors predicting unfavorable outcome included pupillary abnormality on admission and brain bulging during surgery.

INTERPRETATION

Therapeutic effectiveness of hypothermia was thus limited in patients who presented with these grave symptoms.

Diffusion-weighted EPI of cystic ovarian lesions: evaluation of cystic contents using apparent diffusion coefficients

Diffusion-weighted echoplanar imaging (EPI) was performed to evaluate the contents of cystic ovarian lesions [33 endometrial cysts, 16 ovarian cysts, 5 serous cystadenomas, 6 mucinous cystadenomas, 13 malignant cystic ovarian tumors, and 3 benign cystic lesions mimicking malignant cystic ovarian tumor (BMMs)]. Apparent diffusion coefficient (ADC) values were calculated for the cystic contents. Many lesions showed unrealistically high ADC greater than water at body temperature (0.00324 mm(2)/sec), especially in lesions more than 12 cm in diameter. The higher ADC values were attributed to the sloshing effect: intermittent compression of large ovarian lesions by abdominal breathing before the breath-hold scan. When limited to lesions with ADC less than 0. 00324 mm(2)/sec, endometrial cysts and malignant cystic ovarian tumors showed lower ADC values than ovarian cysts and serous cystadenomas (P < 0.03). When further limited to lesions less than 12 cm in axial diameter, an additional ADC difference between malignant cystic ovarian BMMs was demonstrated (P < 0.03). Diffusion-weighted EPI showed the possibility that calculated ADC values might be useful in evaluating small to medium cystic ovarian lesions. J. Magn. Reson. Imaging 2000;12:1014-1019.

Diffusion-weighted EPI of cystic ovarian lesions: evaluation of cystic contents using apparent diffusion coefficients

Diffusion-weighted echoplanar imaging (EPI) was performed to evaluate the contents of cystic ovarian lesions [33 endometrial cysts, 16 ovarian cysts, 5 serous cystadenomas, 6 mucinous cystadenomas, 13 malignant cystic ovarian tumors, and 3 benign cystic lesions mimicking malignant cystic ovarian tumor (BMMs)]. Apparent diffusion coefficient (ADC) values were calculated for the cystic contents. Many lesions showed unrealistically high ADC greater than water at body temperature (0.00324 mm(2)/sec), especially in lesions more than 12 cm in diameter. The higher ADC values were attributed to the sloshing effect: intermittent compression of large ovarian lesions by abdominal breathing before the breath-hold scan. When limited to lesions with ADC less than 0. 00324 mm(2)/sec, endometrial cysts and malignant cystic ovarian tumors showed lower ADC values than ovarian cysts and serous cystadenomas (P < 0.03). When further limited to lesions less than 12 cm in axial diameter, an additional ADC difference between malignant cystic ovarian BMMs was demonstrated (P < 0.03). Diffusion-weighted EPI showed the possibility that calculated ADC values might be useful in evaluating small to medium cystic ovarian lesions. J. Magn. Reson. Imaging 2000;12:1014-1019.

Plasma levels of matrix metalloproteinase-9 and tissue inhibitor of metalloproteinase-1 are increased in the coronary circulation in patients with acute coronary syndrome

BACKGROUND

Previous studies on atherectomy specimens from patients with acute coronary syndrome (ACS) implicated the role of proteolytic enzymes. We examined whether the plasma levels of matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of metalloproteinase-1 (TIMP-1) were increased in the coronary circulation in ACS.

METHODS AND RESULTS

The plasma levels (nanograms per milliliter) of MMP-9 and TIMP-1 in the aorta (Ao) and great cardiac vein (GCV) were measured in 29 patients with ACS (20 with acute myocardial infarction [group 1] and 9 with unstable angina [group 2]), 17 with stable effort angina (group 3), and 20 control subjects (group 4). Group 1 patients had occlusion in the left anterior descending artery (LAD), and groups 2 and 3 patients had culprit lesion in the LAD. In group 1 blood samples were obtained at the time of direct coronary angioplasty done within 12 hours after the onset. The Ao level of either MMP-9 or TIMP-1 did not differ among the 4 groups. The GCV-Ao differences in MMP-9 and TIMP-1 were both significantly increased in groups 1 and 2 compared with those in group 4. Neither of them was different between groups 3 and 4. Neither the GCV-Ao difference in MMP-9 or TIMP-1 level was correlated with the maximal creatine kinase level in group 1.

CONCLUSIONS

Increased plasma levels of MMP-9 and TIMP-1 were detected in the coronary circulation in ACS patients, suggesting a process of active plaque rupture in ACS.

Diffusion-weighted EPI of cystic ovarian lesions: evaluation of cystic contents using apparent diffusion coefficients

Diffusion-weighted echoplanar imaging (EPI) was performed to evaluate the contents of cystic ovarian lesions [33 endometrial cysts, 16 ovarian cysts, 5 serous cystadenomas, 6 mucinous cystadenomas, 13 malignant cystic ovarian tumors, and 3 benign cystic lesions mimicking malignant cystic ovarian tumor (BMMs)]. Apparent diffusion coefficient (ADC) values were calculated for the cystic contents. Many lesions showed unrealistically high ADC greater than water at body temperature (0.00324 mm(2)/sec), especially in lesions more than 12 cm in diameter. The higher ADC values were attributed to the sloshing effect: intermittent compression of large ovarian lesions by abdominal breathing before the breath-hold scan. When limited to lesions with ADC less than 0. 00324 mm(2)/sec, endometrial cysts and malignant cystic ovarian tumors showed lower ADC values than ovarian cysts and serous cystadenomas (P < 0.03). When further limited to lesions less than 12 cm in axial diameter, an additional ADC difference between malignant cystic ovarian BMMs was demonstrated (P < 0.03). Diffusion-weighted EPI showed the possibility that calculated ADC values might be useful in evaluating small to medium cystic ovarian lesions. J. Magn. Reson. Imaging 2000;12:1014-1019.

Enhanced phospholipase C activity in the cultured skin fibroblast obtained from patients with coronary spastic angina: possible role for enhanced vasoconstrictor response

OBJECTIVES

We measured phospholipase C (PLC) activity in the cultured skin fibroblasts obtained from patients with and without coronary spasm and examined its correlation with coronary artery vasomotility.

BACKGROUND

Coronary artery vasomotility is enhanced in coronary spastic angina (CSA), but no information is available for the intracellular signaling. In spontaneously hypertensive rats, PLC activity in the skin fibroblasts has been shown to be enhanced.

METHODS

Skin fibroblasts obtained from 24 patients with CSA-14 with organic coronary artery disease (CAD) and 12 control subjects--were cultured by the explant method. Activity of PLC was determined by incubating the membrane fraction with 3H-phosphatidyl inositol bisphosphate and by quantifying 3H-inositol trisphosphate. In patients with CSA and control subjects, the relations between PLC activity and coronary artery basal tone and constrictor response to intracoronary acetylcholine (ACh) were examined.

RESULTS

Activity of PLC (pmol/protein [mg] per min) was 1.74+/-0.19 in patients with CSA; 0.90+/-0.12 in patients with CAD; and 0.65+/-0.07 in control subjects (p<0.001, patients with CSA vs. patients with CAD and control subjects; p = NS, patients with CAD vs. control subjects). According to the Lineweaver-Burk plot, Michaelis constant (micromol/liter) of PLC was 28+/-4 in patients with CSA; 49+/-14 in patients with CAD; and 56+/-10 in control subjects (p<0.05, patients with CSA vs. control subjects), whereas the maximal velocity was not different between the three groups. There were significant positive correlations between PLC activity and both basal tone (p = 0.0108) and response to ACh (p = 0.0053). Western blot analysis using membrane fraction demonstrated that 89% of PLC isoenzymes detected was of the delta1 isoform.

CONCLUSIONS

Because the PLC activity measured was genetically defined and was positively correlated with coronary artery vasomotility, enhanced PLC activity may be involved in the pathogenesis of coronary spasm.

Dynamic contrast-enhanced MR imaging of the water fraction of normal bone marrow and diffuse bone marrow disease

PURPOSE

To clarify the contrast-enhancement pattern of the normal hematopoietic element by isolating the signal of the water fraction in vertebral bone marrow and to investigate whether this approach can be used to characterize bone marrow pathology in several diffuse bone marrow diseases.

METHODS

Two groups were examined: 30 normal healthy volunteers and 19 patients with primary diffuse bone marrow disease (aplastic anemia [n=8], myelodysplastic syndrome (MDS) [n=5], chronic myelogenic leukemia (CML) [n=4], polycythemia vera [n=2]). Isolation of the signal of hematopoietic tissue was done by the chemical-shift misregistration effect. Twenty consecutive T1-weighted midsagittal lumbar vertebral images were obtained immediately after the intravenous administration of Gd-DTPA of 0.1 mmol/kg body weight, and the pattern of the time-intensity curve, the peak contrast-enhancement (CE) ratio, and the washout rate (%/min) of bone marrow in normal volunteers were compared with those in patients suffering from primary diffuse bone marrow disease.

RESULTS

The pattern of the time-intensity curve of patients with aplastic anemia showed a low peak value followed by a slow washout. However, the pattern of time-intensity curves in patients with MDS, CML, and polycythemia vera was similar to that of normal volunteers. The peak CE ratio of the water fraction in normal marrow ranged from 0.45 to 1.26 (mean +/- S.D.: 0.87 +/- 0.18). Patients with aplastic anemia showed an abnormally lower peak CE ratio of the water fraction (mean +/- S.D.: 0.34 +/- 0.19, p<0.0001). On the other hand, the peak CE ratio of the water fraction in patients with MDS was significantly higher than that of normal volunteers (mean +/- S.D. 1.35 +/- 0.39, p<0.05). In contrast, the peak CE ratio of patients with CML or polycythemia vera did not differ significantly from that of normal volunteers. The mean washout rate of patients with aplastic anemia was significantly lower than that of normal volunteers (mean +/- S.D.: 3.50 +/- 2.51%/min vs. 7.13 +/- 1.74%/min, p<0.01). However, there was no significant difference in the washout rate among patients with MDS, CML, polycythemia vera, and normal volunteers.

CONCLUSION

Dynamic contrast-enhanced MR imaging of the water fraction provides additional valuable qualitative information about structural changes of the hematopoietic element.

Influence of Gelation Temperature and Catalysts on the Mesoporous Structure of Resorcinol-Formaldehyde Aerogels

Resorcinol-formaldehyde (RF) hydrogels were synthesized by sol-gel polycondensation of resorcinol with formaldehyde using a few kinds of catalysts at a gelation temperature of 238 or 332 K. RF aerogels were prepared by supercritical drying with carbon dioxide. The aerogels were characterized by nitrogen adsorption. The experimental results suggest that the gelation temperature does not greatly influence the porous properties and that sodium hydroxide and sodium hydrogencarbonate can be used as catalysts in the preparation of the aerogels. Copyright 2000 Academic Press.

Time course of free radical production after primary coronary angioplasty for acute myocardial infarction and the effect of vitamin C

Reactive oxygen species are thought to mediate reperfusion injury after rapid revascularization for acute myocardial infarction (AMI) and 8-epi prostaglandin (PG) F2alpha, a free-radical catalyzed product of arachidonic acid, has been proposed as an indicator of oxidative stress in vivo during myocardial reperfusion. The time course of urinary 8-epi PGF2alpha excretion after primary coronary angioplasty (PTCA) for AMI was investigated, as well as the effect of prior administration of vitamin C. Urine samples, 1 before and 5 after primary PTCA (0-30, 30-60, 60-90, 90-120 and 120-150 min), were collected in 11 patients with AMI undergoing primary PTCA (Group 1), 10 patients with AMI treated with water-soluble vitamin C at an initial dose of 2.0 g followed by a constant infusion at 20mg/min prior to primary PTCA (Group 2), and 6 patients with stable effort angina undergoing elective PTCA (Group 3). 8-epi PGF2alpha was measured by enzyme immunoassay. There were no significant differences in urinary 8-epi PGF2alpha excretion at baseline among the 3 groups. In Group 1, urinary 8-epi PGF2alpha excretion (ng/mmol creatinine) significantly increased from 60+/-8 at baseline to 122+/-16 at 60-90 min (p<0.001), and declined to the baseline level at 120-150 min after primary PTCA. In Group 2, it also increased from 72+/-12 to 123+/-15 at 60-90 min (p<0.01), and the percent increase did not differ from that in Group 1. In Group 3, it remained unchanged during the study period. The free radical production is rapidly and transiently enhanced after primary PTCA for AMI, and vitamin C fails to suppress it.

Evaluation of cystic ovarian lesions using apparent diffusion coefficient calculated from reordered turboflash MR images

Reordered snapshot fast low-angle shot images with, and without, diffusion-perfusion gradients were used for the evaluation of contents of cystic ovarian lesions. Sonographically detected 51 cystic ovarian lesions (13 endometrial cysts, 17 ovarian cysts, 7 serous cystadenomas, 6 mucinous cystadenomas, 8 malignant cystic ovarian tumors) were studied. T1- and T2-weighted images, reordered snapshot fast low-angle shot images with and without diffusion-perfusion gradients (b = 106 and 0 s/mm2, respectively) were obtained. Using these images, apparent diffusion coefficients (ADCs) were calculated in the cystic contents of these lesions. Endometrial cysts and malignant cystic ovarian tumors showed lower ADC values than ovarian cysts, serous cystadenomas and mucinous cystadenomas (p < 0.02). There was no distinct ADC difference among ovarian cysts, serous cystadenomas, mucinous cystadenomas (p > 0.2). In conclusion, diffusion-weighted magnetic resonance imaging is possible to be useful to evaluate cystic contents of ovarian lesions.

Intact PTH-producing hepatocellular carcinoma treated by transcatheter arterial embolization

We report a case of hepatocellular carcinoma with hypercalcemia. There was no evidence of bone metastasis or increase in parathyroid hormone-related protein. The serum level of intact parathyroid hormone (intact PTH) was very high, and the results of the hepatic venous sampling suggested that the tumor produced intact PTH. Transcatheter arterial chemoembolization effectively controlled the humoral hypercalcemia.

Coronary arteriolar dilation to acidosis: role of ATP-sensitive potassium channels and pertussis toxin-sensitive G proteins

BACKGROUND

We previously demonstrated that coronary arteriolar dilation in response to acidosis is mediated by the opening of ATP-sensitive potassium (KATP) channels. However, the signal transduction involved in the KATP-channel activation during acidosis has not been elucidated. A recent study in cardiac myocytes implied that pertussis toxin (PTX)-sensitive G proteins may be involved in the signal transduction for KATP-channel activation. However, it remains unclear whether this transduction process also occurs in the vascular tissue and, in particular, whether it exerts functional dilation in response to acidosis.

METHODS AND RESULTS

To examine the signaling pathway for acidosis-induced dilation, porcine coronary arterioles were isolated, cannulated, and pressurized for in vitro study. The GTPase activity in reconstituted G proteins was examined at different levels of pH. Extravascular acidosis (pH 7.3 to 7.0) produced a graded dilation of coronary arterioles. This dilation was not affected by removal of endothelium but was significantly attenuated after inhibition of KATP channels and G proteins by glibenclamide and PTX, respectively. Glibenclamide and PTX attenuated the acidosis-induced arteriolar dilation to the same extent, and combined administration of both inhibitors did not further inhibit the vasodilation. These results indicated that both inhibitors act on the same vasodilatory pathway. Furthermore, vasodilation of coronary arterioles to the KATP-channel opener pinacidil and to the endothelium-independent vasodilator sodium nitroprusside was not affected by PTX. Because PTX inhibited acidosis-induced vasodilation without inhibiting KATP-channel function, it is suggested that PTX inhibits the vasodilatory pathway upstream from KATP channels. GTPase activity in reconstituted G proteins was significantly enhanced by a reduction in pH, indicating that G proteins were directly activated by acidosis.

CONCLUSIONS

On the basis of these findings, we conclude that acidosis-induced coronary arteriolar dilation is mediated by the opening of smooth muscle KATP channels through the activation of PTX-sensitive G proteins.

SAXS Study on Gelation Process in Preparation of Resorcinol-Formaldehyde Aerogel

RF aerogels were prepared by sol-gel polycondensation of resorcinol with formaldehyde in a slightly basic aqueous solution and supercritical drying with carbon dioxide. The aerogels were characterized by nitrogen adsorption and density measurements. A small-angle X-ray scattering (SAXS) technique was applied to the gelation process of RF hydrogels. The structure formation of the hydrogels during the sol-gel transition was revealed by applying Guinier and power-law equations to the SAXS data. At the initial stage of the synthesis of RF hydrogels, small clusters of ca 2 nm consisting of branched polymeric species formed, showing a mass fractal dimension. Then the clusters aggregated and formed particles of ca 3-6 nm. These particles showed a surface fractal dimension. The hydrogel structure was fixed by gelation and the particles grew to ca 4-7 nm. Finally their surface became smooth by aging. The influence of the amount of resorcinol, basic catalyst, and water used in the polycondensation on the porous structures of the aerogels was explained by the structure formation model proposed. Copyright 1998 Academic Press.

Evaluation of cystic ovarian lesions using apparent diffusion coefficient calculated from turboFLASH MR images

Serial turboFLASH (fast low-angle shot) images with and without diffusion-perfusion (DP) gradients were used to evaluate the contents of cystic ovarian lesions. 19 ovarian cysts seven serous cystadenomas, six mucinous cystadenomas and 13 malignant cystic ovarian tumours were studied. T1 and T2 weighted spin echo images, serial turboFLASH images with and without DP gradients (b = 295.1 and 0 s mm-2, respectively) were obtained. Using these images, the apparent diffusion coefficients (ADCs) were calculated within the cystic contents of these lesions. Approximately corrected ADC (ADC') values were also calculated in order to reduce T1 contamination from ADCs, using results of a phantom study. Ovarian cysts and serous cystadenomas showed larger ADC and ADC' values than the cystic contents of malignant ovarian lesions (p < 0.01). Mucinous cystadenomas show no distinct ADC difference to any other group of cases. However, if the highest ADC' loculus was selected as being representative, mucinous cystadenomas showed a larger ADC' value than malignant cystic neoplasms (p < 0.03). In conclusion, diffusion-weighted MRI is possibly of use in evaluating cystic contents of ovarian lesions.

Correlation of T1 and T2 relaxation rates in normal bone-marrow water with serum ferritin concentration

PURPOSE

This study was made to clarify the paramagnetic effect of iron stored in the hematopoietic tissue of bone marrow.

MATERIAL AND METHODS

The T1 and T2 relaxation times of bone-marrow water in the L1-3 vertebrae of 20 healthy individuals were measured by MR imaging with a 1.5 T magnet. The chemical shift misregistration effect was used to isolate the bone-marrow water. The results were compared with the serum ferritin concentration.

RESULTS AND CONCLUSION

Although no correlation between the T1 relaxation rate of the water fraction and the serum ferritin concentration was evident, the T2 relaxation rate of the water fraction showed strong linear correlation with the serum ferritin concentration (r = 0.87, p < 0.0001). Thus, T2 of bone-marrow water accurately reflects the amount of iron in normal bone marrow. This finding may be useful in the evaluation of the characteristics of hematopoietic tissue in bone marrow.

Compulsory superselective arterial embolization in hypovascular local hepatic tumor ablation. Microballoon coaxial catheterization

We performed compulsory superselective transcatheter arterial embolization on local hypovascular liver metastases under balloon occlusion using a 1-mm (3 F) coaxial microballoon catheter in 2 cases. One case was a metastasis from breast cancer (maximum diameter 5.5 cm) at segment 7. The other case comprised metastases from rectal cancer (maximum diameter 8 cm) at segments 7 and 8. Absolute ethanol (50%) mixed with Lipiodol (50%) was used for embolization. No major treatment-related complications occurred. No local recurrence was observed in either case in follow-up CT and MR studies of up to 16 and 9 months respectively. This technique may thus be applied as an alternative to surgical resection in the treatment of local hypovascular liver tumors.

Partial renal embolization for pediatric renovascular hypertension secondary to fibromuscular dysplasia

We report a 7-year-old boy with renovascular hypertension showing multiple stenoses and microaneurysms of the dorsal branch of the left renal artery caused by fibromuscular dysplasia. Hypertension was successfully treated with transcatheter alcohol and gelatin sponge embolization of the dorsal branch and its distribution. The vertebral branch remained intact. No severe complication was encountered. Loss of renal function by renal scintigraphy was minimal. The patient remains asymptomatic at 1 year.

Usefulness of preoperative MRI diagnosis in prostatic adenocarcinoma

BACKGROUND

We examined the reliability of an MRI diagnosis prior to radical prostatectomy for prostate cancer.

METHODS

A radical prostatectomy was performed in 24 patients with prostate cancer. Resected specimens were fixed and 5 mm step sections vertical to the urethra were prepared to resemble MRI images. We compared this pathological map with the preoperative MRI diagnosis which included capsular or seminal vesicle invasion and tumor localization in the prostate. We defined a new criterion for the presence of capsular invasion as a chemical shift that occurred on the rectal side on T1-weighted images 5 minutes after gadolinium (Gd) enhancement and the periprostatic venous plexus was not serial. We also examined 4 diagnostic factors of tumor localization including a low-signal intensity area detected in the peripheral zone on T2-weighted images, the presence of an enhanced area on Gd-enhanced T1-weighted images, and a low T2 with either Gd-enhanced or nonenhanced T1-weighted images.

RESULTS

The accuracy of a preoperative MRI diagnosis of capsular invasion was 16.7% using the conventional criteria, but 88.9% adding the new criterion. The accuracy of predicting seminal vesicle invasion was 63.2% in a group using a body surface coil compared to 75% in the group using an endorectal surface coil. The accuracy, positive predictive value, sensitivity and specificity of diagnosing tumor localization were 69%, 74.4%, 35.1%, and 91.8%, respectively.

CONCLUSION

This new criterion proved superior for diagnosing capsular invasion in prostate cancer patients. Also, analysis of tumor localization in the peripheral zone demonstrated that cancer detection is increased if the low-signal intensity area is enhanced by Gd.

Endothelial ATP-sensitive potassium channels mediate coronary microvascular dilation to hyperosmolarity

Coronary arterial occlusion has been shown to increase osmolarity in the myocardial interstitium. Intracoronary injection of hyperosmolar solutions reduces coronary vascular resistance. However, the response of coronary microvessels to an abluminal increase in osmolarity is unclear, and the underlying mechanism for its vasomotor regulation has not been elucidated. In this regard, porcine coronary arterioles (81 +/- 2 microns) were isolated, cannulated, and pressurized for in vitro study. Hyperosmolarity (300-345 mosM) was produced by adding D-glucose or D-sucrose to the extravascular solution. After the arterioles developed a stable vascular tone, a graded vasodilation was observed when glucose or sucrose was incrementally administered. This hyperosmotic vasodilation was abolished after endothelial removal. Intraluminal administration of KCl (80 mM) or the ATP-sensitive potassium (KATP)-channel inhibitor glibenclamide (1 microM) to the intact vessels significantly attenuated the hyperosmotic vasodilation. Inhibition of inward rectifier potassium channels by a low concentration of BaCl2 (10 microM) did not affect vasodilation. However, a high concentration of BaCl2 (100 microM), which has been reported to inhibit KATP channels, attenuated the hyperosmotic vasodilation. Iberiotoxin (100 nM), a calcium-activated potassium (KCa)-channel inhibitor had no effect on hyperosmolarity-induced vasodilation. Inhibition of the synthesis of endothelial nitric oxide, prostaglandins, and arachidonic acid metabolites from cytochrome P-450 had no effect on hyperosmotic vasodilation. Furthermore, inhibition of vascular smooth muscle KATP channels and the large- and small-conductance KCa channels by extraluminal administration of glibenclamide, iberiotoxin, and apamin, respectively, did not alter vasodilation in response to hyperosmolarity. These results indicate that dilation of coronary arterioles in response to hyperosmotic stimulation requires an intact endothelium. However, the response is independent of the release of nitric oxide, prostaglandins, or cytochrome P-450-related endothelium-derived hyperpolarizing factor and is not a result of activation of KATP and KCa channels in vascular smooth muscle. It is suggested that the opening of KATP channels in vascular endothelium and subsequent hyperpolarization of that cell type mediate coronary microvascular dilation in response to hyperosmolarity.

T2 relaxation time of bone marrow water and lipid: correlation with serum ferritin in normal individuals

PURPOSE

This study investigated the correlation between the iron content of bone marrow and the transverse relaxation times (T2 values) of bone marrow water and lipid on MRI.

METHOD

The T2 of the water and lipid fractions of bone marrow was selectively measured in the L1-3 vertebral bodies using the chemical shift misregistration effect on MRI. Results were compared to the serum ferritin levels in 27 healthy subjects.

RESULTS

The 1/T2 of the water fraction ws strongly correlated with the serum ferritin, but there was no correlation between the 1/T2 of the lipid fraction and serum ferritin.

CONCLUSION

Selective T2 measurement of the water fraction in bone marrow allows precise estimation of the marrow iron content.

Water fraction of lumbar vertebral bone marrow estimated from chemical shift misregistration on MR imaging: normal variations with age and sex

OBJECTIVE

Our objective was to use the chemical-shift misregistration effect of MR imaging to measure the variation in the water fraction in vertebral bone marrow with respect to patient age and sex.

SUBJECTS AND METHODS

We examined prospectively 211 subjects (5-84 years old; 108 male and 103 female subjects) who had no history of hematologic disorders. We obtained midsagittal proton density-weighted spin-echo images (2500/22 [TR/TE]) with a narrow sampling bandwidth (6250 Hz). Misregistered signals from lipid protons of 6-10 mm (upward shift in the readout direction) were obtained with the chemical-shift effect. By measuring the mean signal intensities of the water voxels and the water-plus-lipid voxels, we calculated a region of interest in each vertebral body for L1 to L3. The water fraction of bone marrow was then calculated as 100 x (signal intensity of water voxels/signal intensity of water-plus-lipid voxels). Individual water fractions were calculated from the average values for the water fractions of the L1-L3 bodies.

RESULTS

In the male subjects, the water fraction showed a rapid decrease in the older patients in the 5- to 34-year-old group. (Mean water fractions for male patients who were 5-14, 15-24, and 25-34 years old were 75.2%, 69.0%, and 53.7%, respectively.) For male patients more than 25 years old, the water fraction remained almost constant (approximately 50%). In female subjects who were 5-44 years old, the water fraction exceeded 69% and remained almost constant. However, the water fraction rapidly decreased in women more than 45 years old. (Mean water fractions for female patients who were 35-44, 45-54, and 55-64 years old were 70.9%, 61.1%, and 49.7%, respectively.) A comparison between male subjects and female subjects showed that the water fraction for women who were 25-54 years old exceeded the water fraction for men in the same age group (25-34 years old, p < .0001; 35-44 years old, p < .001; 45-54 years old, p < .05).

CONCLUSION

MR imaging showed that male and female subjects convert hematopoietic marrow to fatty marrow in the lumbar vertebral bodies in significantly different ways. The data obtained for the normal water fraction of bone marrow may prove useful for evaluating diseases that affect marrow.

Impairment of coronary blood flow regulation by endothelium-derived nitric oxide in dogs with alloxan-induced diabetes

Diabetes mellitus is a major cause of ischemic coronary artery disease. Endothelial dysfunction is implicated in the pathogenesis of diabetic vascular disease. To examine coronary blood flow (CBF) regulation with endothelium-derived nitric oxide (EDNO) in the diabetic state, we compared the effects of both acetylcholine (ACh) and adenosine (Ado) on left circumflex coronary artery (LCX) blood flow in 12 vehicle-treated and 21 dogs made diabetic with alloxan anesthetized with pentobarbital. All dogs were pretreated with aspirin to inhibit endogenous prostaglandins. None of the hemodynamic parameters were significantly different in the two groups. The percent change in coronary vascular resistance (CVR) after ACh (100 ng/kg) infusion was significantly attenuated in diabetic dogs (-56.5 +/- 1.4%) as compared with vehicle-treated dogs (-64.5 +/- 1.2%) (p < 0.01), whereas the effect of Ado (1 microgram/kg) was not different between the two groups (-71.1 +/- 1.5% in vehicle, -67.0 +/- 1.3% in diabetes). After infusion of incremental doses of NG-nitro-L-arginine methyl ester (L-NAME) 10(-5)-10(-3)M, the effect of ACh was progressively inhibited in both groups and was different no longer between the two groups after the maximal dose. L-Arginine (L-ARG), but not D-ARG, significantly restored the effect of ACh in diabetic dogs but did not affect vehicle-treated dogs. The effect of Ado did not change after L- and D-ARG administration. Cu, Zn-superoxide dismutase (Cu, Zn-SOD) had no effect on any of the effects of ACh and Ado in diabetic dogs. Regulation of CBF with EDNO is impaired in dogs with alloxan-induced diabetes, and this impairment is partially restored by L-ARG.

Enhancement of myocardial reactive hyperemia with manganese-superoxide dismutase: role of endothelium-derived nitric oxide

OBJECTIVE

To test the hypothesis that superoxide radicals generated during myocardial ischemia and reperfusion influence reactive hyperemia (RH) by reacting with endothelium-derived nitric oxide (EDNO), we examined the effect of manganese (Mn)-superoxide dismutase (SOD) on RH in anesthetized dogs.

METHODS

Twelve dogs were pretreated with 8-phenyltheophylline (8PT) to block adenosine's effect. Five dogs were pretreated with 8PT and NG-nitro-L-arginine methyl ester (L-NAME) to block adenosine's and EDNO's effects. Following occlusion of the left circumflex artery (LCX) for 10 and 60 s, RH was observed before and after Mn-SOD. In another group of 6 dogs pretreated with 8PT, RH following 60-s LCX occlusion was observed before and after Mn-SOD and catalase. For comparison with the effect of Mn-SOD, that of copper, zinc (Cu,Zn)-SOD was also examined in another group of 5 dogs.

RESULTS

In the dogs pretreated with 8PT, Mn-SOD significantly increased excess flow and repayment of flow debt during RH after 60-s LCX occlusion but did not affect RH after 10-s LCX occlusion. Mn-SOD-induced augmentation of RH following 60-s LCX occlusion was not affected by catalase, while it was completely abolished by L-NAME. In contrast to Mn-SOD, Cu,Zn-SOD showed no effect on RH following 60-s LCX occlusion in the dogs pretreated with 8PT.

CONCLUSIONS

Superoxide radicals generated during ischemia for 60 s and reperfusion attenuates myocardial RH through inactivation of EDNO. Mn-SOD shows more beneficial effects on myocardial RH than Cu,Zn-SOD.

Distinguishing between cystic teratomas and endometriomas of the ovary using chemical shift gradient echo magnetic resonance imaging

The purpose of this study was to evaluate the efficacy of chemical shift gradient echo magnetic resonance imaging (MRI) in distinguishing between cystic teratomas and endometriomas of the ovary, using a 1.5T magnet. The study included 22 patients with 31 ovarian lesions (15 cystic teratomas and 16 endometriomas), which showed high signal intensity on T1-weighted spin echo images. Chemical shift gradient echo images with three different echo times (TE = 2.5, 4.5 and 6.5 ms) were obtained in all cases. Indices were calculated on the basis of the signal intensities of lesions on the chemical shift gradient echo images. All endometriomas had signal intensity indices of less than 2.1, while all cystic teratomas had signal intensity indices of 18.1 or greater. Chemical shift gradient echo imaging is an alternative method that is useful and simple for distinguishing between cystic teratomas and endometriomas of the ovary.

Diffuse disorder of coronary artery vasomotility in patients with coronary spastic angina. Hyperreactivity to the constrictor effects of acetylcholine and the dilator effects of nitroglycerin

OBJECTIVES

We examined the vasomotility of the entire epicardial coronary artery system in patients with and without coronary spastic angina.

BACKGROUND

The coronary arteries of patients with variant angina are hyperreactive to diverse constrictor stimuli. It is unclear whether the abnormal responses to constrictive or dilative stimuli, or both, result from a localized or diffuse disorder in the coronary artery tree.

METHODS

Coronary artery diameter responses to intracoronary acetylcholine and nitroglycerin were examined at the proximal, middle and distal segments of three principal coronary arteries in 36 patients with coronary spastic angina without significant stenosis and in 12 young (< or = 30 years old) and 20 older control subjects (> 30 years old) with normal coronary arteriographic findings. In 10 patients with significant coronary stenosis, the responses of the prestenotic segments were also examined.

RESULTS

In patients with coronary spastic angina, coronary spasm was induced in 23 left anterior descending, 13 left circumflex and 17 right coronary arteries by acetylcholine. Multivessel spasm was observed in 15 patients. Acetylcholine had a dilator effect on most segments in young control subjects and a mild constrictor effect in older control subjects and in patients with significant stenosis. Comparison of the responses to acetylcholine among groups demonstrated that the constrictor response of the artery with spasm was enhanced significantly and diffusely. That of the artery without spasm also tended to be enhanced. Coronary artery diameters after nitroglycerin did not differ in any segment among patients with coronary spastic angina and both control groups. In patients with coronary spastic angina, nitroglycerin significantly enhanced dilation in all segments of the artery with spasm compared with that observed in both control groups and in most segments of the artery without spasm. Patients with significant coronary stenosis had a reduced response compared with that in control subjects.

CONCLUSIONS

Hyperreactive responses not only to the constrictor effects of acetylcholine, but also the dilator effects of nitroglycerin were detected diffusely in the epicardial coronary arteries of patients with coronary spastic angina. This finding indicates that a diffuse, not localized, disorder in vasomotility is involved in the pathogenesis of coronary spastic angina.

Acidosis-induced coronary arteriolar dilation is mediated by ATP-sensitive potassium channels in vascular smooth muscle

Although a decrease in extravascular pH has been suggested to be involved in coronary flow regulations during hypoxia, ischemia, and increased metabolic demand of the heart, its vasomotor control mechanism has not been elucidated. To examine the effect of acidosis of vasomotor tone, porcine coronary arterioles (40 to 110 microns) were isolated, cannulated, and pressurized to 60 cm H2O intraluminal pressure without flow for in vitro study. Acidosis (pH 7.4 to 7.0) was produced by adding HCl to the extravascular solution. The involvement of potassium channels in the vasomotor response to acidosis was evaluated by using BaCl2 (100 mumol/L, nonspecific potassium channel inhibitor), glibenclamide (5 mumol/L, ATP-sensitive potassium channel inhibitor), and iberiotoxin (100 nmol/L, calcium-activated potassium channel inhibitor). To determine whether endothelial hyperpolarization contributes to the acidosis-induced dilation, the pH-diameter relation of the vessel was examined under a high intraluminal concentration of KCl (40 mmol/L). The involvement of nitric oxide and prostaglandins was assessed by using NG-monomethyl-L-arginine (L-NMMA, 10 mumol/L) and indomethacin (10 mumol/L), respectively. To evaluate the role of endothelium in the acidosis-induced dilation, the pH-diameter relation was studied after endothelial removal. All vessels developed a similar level of spontaneous tone (internal diameter, 75 +/- 4 microns [approximately 69 +/- 1% of maximum diameter) and dilated to HCl in dose-dependent manner. Glibenclamide completely abolished vasodilation to a mild level of acidosis (pH 7.2 to 7.3) and attenuated the vasodilation by 70% at pH 7.0. Acidosis-induced dilation was also inhibited by BaCl2 but not by iberiotoxin. L-NMMA, indomethacin, and intraluminal KCl did not alter the pH-diameter relation. Vasodilation to acidosis of the endothelium-denuded vessels was identical to that of the endothelium-intact vessels. In addition, glibenclamide attenuated the acidosis-induced arteriolar dilation of endothelium-denuded vessels. These results suggest that the opening of ATP-sensitive potassium channels in vascular smooth muscle mediates the coronary arteriolar dilation during acidosis.

Bone marrow cellularity: quantification by chemical-shift misregistration in magnetic resonance imaging and comparison with histomorphometrical techniques

The accuracy of a technique that uses chemical-shift misregistration in magnetic resonance (MR) imaging to quantify vertebral bone marrow cellularity was tested on cadaveric specimens. In order to estimate the cellularity of 11 unfixed vertebral bodies, mid-sagittal MR images were obtained using a 1.5T magnet with a proton-density-weighted spin-echo sequence (repetition time/echo time, 2500/22 ms) and a narrow bandwidth. These values were subsequently compared to the histomorphometrical values for cellularity, amount of trabecular bone and deposited iron. The image-derived values for cellularity (VI, %) correlated well with values determined by histomorphometry (VH, %) (VI = 21.2 + 0.72 VH, r = 0.92) regardless of the presence of trabecular bone and small amount of stored iron in the specimens. This simple technique may be applicable in the estimation of marrow cellularity.

Differential diagnosis of renal lesions with US-angiography using intra-arterial CO2 microbubbles

To differentiate renal masses, 58 patients with renal masses (39 men and 19 women, aged 23-81 years [mean age 60 years]) underwent US-angiography with intra-arterial infusion of carbon dioxide (CO2) microbubbles during conventional angiography; 32 patients had renal cell carcinomas; nine, transitional cell carcinomas; nine, renal complicated cysts; four, angiomyolipomas; two, acute focal bacterial nephritis and hematomas. Renal masses were classified into six enhancement patterns of US-angiography. Thirty-one (97%) renal cell carcinomas were histologically alveolar type and demonstrated the well-enhancement pattern. All nine renal complicated cysts showed the non-enhancement pattern. Although transitional cell carcinomas did not show definite neovascularity on conventional angiography, they were classified as the well-enhancement pattern in 4/9 (44%) and poor-enhancement pattern in 5/9 (56%) on US-angiography. Four angiomyolipomas were homogeneously enhanced. Complicated cysts were clearly differentiated from renal cell carcinomas by the enhancement pattern on US-angiography. But the differentiation between renal cell carcinomas and angiomyolipomas was difficult. US-angiography is useful for detecting fine neovascularity of renal lesions and also for the differentiation or renal cell carcinomas from complicated cysts or transitional cell carcinomas during conventional angiography.

Differentiation between hemangiomas and hepatocellular carcinomas with the apparent diffusion coefficient calculated from turboFLASH MR images

Serial turboFLASH (fast low-angle shot) images with and without diffusion-perfusion (DP) gradients were used for the evaluation of and differentiation between hemangiomas and hepatocellular carcinomas (HCCs) of the liver. Twenty-six patients with 27 hemangiomas, and 19 patients with 21 HCCs were studied. T1- and T2-weighted spin-echo images, serial turboFLASH images with and without DP gradients (b = 294.8 and 0 sec/mm2, respectively) were obtained, and the apparent diffusion coefficient (ADC) was calculated for all lesions. Hemangiomas were detected as well-defined areas of decreased signal intensity on turboFLASH images obtained with DP gradients; HCCs showed slight or no obvious decrease in signal intensity on serial turboFLASH images obtained with DP gradients compared with turboFLASH images obtained without DP gradients, while a considerable percentage (76.5%) of nodular HCCs showed an obvious decrease in signal intensity at the margins. Hemangiomas had large ADC values compared with HCCs. Both ADC and T2 values were significantly different between hemangiomas and HCCs (P < .01). However, there was no obvious correlation between ADC and T2 values for either hemangiomas or HCCs (r = .18 and .48, respectively). On the basis of these results, the calculated ADC should be helpful for distinguishing hemangiomas from HCCs, and the ADC values may be useful even when T2 values are not helpful for making the distinction.

[A case of adenomyelolipoma]

We report case of adenomyelolipoma. CT and MRI revealed a large, capsulated, septated adrenal mass with abundant fat tissue. However, enhancing components were demonstrated at the capsule and septations on angiography. On the pathological study, the capsule and septations consisted of adrenal adenoma and the tumor contained various forms of myelolipomatous tissues. These myelolipomatous tissues were classified into 4 groups. Type I: Scattering of fat cells and hematopoietic elements without coalescence. Type II: Collection of myelolipomatous tissue with unclear margin or small myelolipomatous tissue that cannot be classified as type I or III. Diameter of the lesion is less than 1 cm. Type III: Collection of myelolipomatous tissue with clear margin or replacement of cortical nodule. Diameter of the lesion is less than 1 cm. Type IV: Collection of myelolipomatous tissue. Diameter of the lesion is equal to or greater than 1 cm. We defined adenomyelolipoma as a lesion combining adrenal adenoma (or hyperplasia) and various forms of myelolipomatous tissues (type I-IV) in view of the strong relationship between adrenal adenoma (or hyperplasia) and myelolipomatous tissue.

Hypopituitarism with invisible pituitary stalk: two case reports of males with micropenis suggesting fetal onset of hypopituitarism

The presence of hypopituitarism and invisible pituitary stalk on a magnetic resonance image (MRI) is commonly attributed to birth trauma. Two patients with severe hypopituitarism and invisible pituitary stalk are presented. One was born by breech delivery, the other by Cesarean section. The presence of a micropenis since early infancy in these two patients suggested that their hypopituitarism might have begun during early fetal life thus effecting penile growth during the second and third triministers of gestation. These findings raise the possibility that the association of hypopituitarism and invisible pituitary stalk may have multiple etiologies including hormonal abnormalities during early fetal life.

Vasodilator effect of carboxy-2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl in the coronary circulation: in vivo and in vitro studies

2-Phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO) derivatives, new radical forms of nitric oxide (NO) antagonists, are reported to react with NO and generate NO2 and 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl (PTI) derivatives. We found that carboxy-PTI, a water-soluble derivative of PTI, showed a potent vasodilator effect in the canine coronary artery system. In anesthetized dogs, intracoronary infusion of carboxy-PTI significantly increased the coronary flow in a dose-dependent manner without altering systemic hemodynamic variables. This coronary flow increasing effect of carboxy-PTI was not influenced by pretreatment with either NG-nitro-L-arginine methyl ester or 8-phenyltheophylline or autonomic blockade. However, the flow increasing effect of carboxy-PTI was abolished by reducing carboxy-PTI with ascorbic acid to a non-radical form of carboxy-PTI, indicating that carboxy-PTI shows its effect only in a radical form. In isolated canine coronary arterial rings, carboxy-PTI caused endothelium-independent relaxation. This relaxation response was significantly attenuated by pretreatment with methylene blue, an inhibitor of soluble guanylate cyclase. Thus, carboxy-PTI has an endothelium-independent coronary vasodilator effect in both large conduit arteries and small resistance vessels. The results of the in vitro experiment suggested that the activation of soluble guanylate cyclase of the vascular smooth muscle cell may be involved, at least in part, in the vasodilator mechanism of carboxy-PTI in large conduit arteries.

Influence of inhibition of endothelium-derived nitric oxide formation to effects of vasoconstrictor agents neuropeptide Y, clonidine, and ergonovine on coronary vascular resistance

To determine whether inhibition of endothelium-derived nitric oxide (EDNO) synthesis enhances the effects of exogenous vasoconstrictor agents on the coronary vasculature, we examined the effects of neuropeptide Y (NPY), clonidine, and ergonovine on coronary vascular resistance (CVR) with and without EDNO inhibitor and compared the results. In 15 anesthetized mongrel dogs, the left circumflex coronary artery (LCX) was perfused with arterial blood from the left common carotid artery through an extracorporeal bypass tube and LCX blood flow was measured with an electromagnetic flowmeter. Nine of the dogs were pretreated with intracoronary NG-nitro-L-arginine methyl ester (L-NAME 300 microM in LCX blood) (L-NAME group) and the other 6 were treated with normal saline (vehicle group). Three doses of NPY (4.3, 43, 430 ng/kg), two doses of clonidine (30 and 300 ng/kg), and one dose of ergonovine (20 micrograms/kg) were infused into LCX. NPY decreased LCX flow and increased CVR dose dependently in both groups, and there was no significant difference in the dose-response relation between the two groups. Clonidine decreased LCX flow and increased CVR in both groups, and there was no difference in the effect between the groups. In contrast, ergonovine decreased LCX flow and increased CVR to a greater degree in the L-NAME group than in the vehicle group (p < 0.01). Thus, inhibition of EDNO synthesis by L-NAME did not result in enhancement of the vasoconstrictor effects of NPY and clonidine, whereas it significantly enhanced the effect of ergonovine, possibly through inhibition of ergonovine-induced EDNO release.

Effect of cumulative doses of NG-nitro-L-arginine methyl ester on coronary blood flow of anesthetized and conscious dogs

To examine the effect of cumulative doses of NG-nitro-L-arginine methyl ester (LNAME), an inhibitor of nitric oxide synthesis, on coronary blood flow, basal left circumflex artery blood flow and acetylcholine-induced flow increment were observed in anesthetized and conscious dogs. Four doses of LNAME (10(-5) M, 10(-4) M, 10(-3) M and 10(-2) M in the left circumflex artery blood were cumulatively infused into the left circumflex artery. All dogs were pretreated with 8-phenyltheophylline and acetylsalicylic acid to inhibit endogenous adenosine and vasodilator prostaglandin, respectively. In anesthetized dogs (n = 10), systolic blood pressure was increased with 10(-2) M of LNAME and heart rate was decreased with > or = 10(-3) M of LNAME. All doses of LNAME significantly decreased the left circumflex artery blood flow in a dose-dependent manner, without affecting the rate-pressure product. The acetylcholine-induced flow increment was significantly attenuated with all doses of LNAME. However, no further attenuation was induced by > or = 10(-3) M of LNAME and the maximal dose did not completely abolish the effect of acetylcholine. In conscious dogs (n = 7), LNAME showed similar effects to those seen in anesthetized dogs: the left circumflex artery blood flow decreased with > or = 10(-4) M of LNAME, without affecting the rate-pressure product; the acetylcholine-induced flow increment was attenuated with > or = 10(-4) M of LNAME, but not completely abolished. Thus, there is a basal nitric oxide release from the endothelium in the coronary resistance vessels of anesthetized and conscious dogs. However, (an)other mechanism(s) than the L-arginine-nitric oxide pathway seem(s) to be involved in the acetylcholine-induced vasodilatation.