Localization of 99mTc-HMDP in hepatic metastases from colonic carcinoma

To evaluate the significance and frequency of skeletal imaging agent localization in hepatic metastases from colonic carcinoma, scintigrams from 54 patients were retrospectively studied. Of 54 patients, 22 had hepatic metastases, and skeletal metastases were present in seven of 54. Six of the seven patients with skeletal metastases had concurrent hepatic deposits. Two patterns of bone agent localization in liver metastases occurred: diffuse and mild (10 patients) and ringlike in appearance (two patients). Twelve of the 22 patients had localization of skeletal imaging agent in hepatic metastases and extensive or large liver lesions. Concurrent serum calcium values for nine of 12 patients were reviewed; none had a high level of serum calcium. Among available plain films and /or CT scans of the abdomen for 21 of the 22 patients, only one patient with extensive colonic metastases had multiple calcifications shown on CT but not seen in plain films. The data indicate a high frequency of hepatic metastases in colon carcinoma (22/54, 40%) and a high frequency of skeletal imaging agent localization in the hepatic colonic metastases (12/22, 54.5%). Once skeletal metastases are observed, there are almost always hepatic metastases present (6/7). There was no relation between elevated serum calcium values and bone agent localization in hepatic deposits. The relation between skeletal imaging agent localization or radiographic calcifications and histopathology of colonic carcinoma was inconclusive. The presence of bone agent localization in a 99mTc hydroxymethylene diphosphonate (HMDP) bone study indicates colonic hepatic metastases that are substantially widespread and/or bulky.     

9:45-10:00. Superimposition of EBCT Determined Coronary Calcium Deposits onto Myocardial PET Perfusion Images by Rubidium-82 and Nitrogen-13 Ammonia for Assessment of Flow Limiting Defects

Calcium localization by Electron Beam CT (EBCT) in the coronary arteries is becoming an important non-invasive method for screening asymptomatic patients for early coronary atherosclerosis. However, the relationship between coronary artery calcium deposits and myocardial perfusion abnormalities has not been established. We have developed software to superimpose location of coronary calcium by EBCT onto PET myocardial perfusion images, so that we can determine the role of location and amount of calcium in the arteries to flow-limiting perfusion defects by PET.EBCT and PET transaxial images are each first converted to three-dimensional arrays of 1 mm voxels. The resulting two image volumes sets are displayed so that a vertical line can be drawn from the clavicle to the spine for proper rotation of the body. The rotated images are then displayed superimposed and are shifted in the vertical, horizontal, and the long axis directions to co-register the EBCT and PET images. The EBCT images are windowed for calcium Houndsfield numbers and calcium location is added to the PET images as a maximum intensity value in the image. The modified PET image volume is then translated back to the PET data format and reprocessed using cardiac analysis software such that the calcium location is superimposed on the PET myocardial perfusion images.Preliminary results of the PET-EBCT superimposition program correlate with location of coronary calcium by EBCT and PET perfusion defects following stress. This technique may be useful for identifying flow-limiting calcium deposits in the coronary arteries.     

动脉内钙剂刺激试验在功能性胰岛素瘤术前定位中的应用

目的:评价动脉内钙剂刺激试验在功能性胰岛素瘤术前定位诊断中的作用。方法:对10例胰岛素瘤患者行动脉内钙剂刺激肝静脉采血试验(ASVS)测定胰岛素的研究,ASVS前均行超声、CT、MRI及内镜超声检查。10例功能性胰岛素瘤均得到手术病理证实,病灶大小为0．8-2．0 cm。分别行胃十二指肠动脉(GDA)、肠系膜上动脉(SMA)、脾动脉近端(sAP)和脾动脉远端(SAD)造影,并通过导管注射钙剂5 m1(含Ca2 约27 mg),于每次动脉刺激后30、60、90、120、 150和180 s行右肝静脉取血测定胰岛素:不同动脉激发试验的间隔时间为15 min。阳性判断标准:若胰岛素峰值达到或超过基础值的4倍以上,即提示该动脉为肿瘤的供血动脉,肿瘤即被定位于相对应的胰腺区域。结果:10例中9例ASVS 结果与最终诊断完全一致,1例肿瘤位于胰尾,因未行SAD激发而漏诊。结论:ASVS是功能性胰岛素瘤安全、准确的术前定位方法,尤其适用于病灶较小、其他影像学检查结果为阴性的病例。     

19. Correlation between FDG PET data and EEG dipole modeling

Purpose: FDG-PET images and EEG dipole modelling were used to localization of interictal epileptogenic foci. A multimodality approach with the analysis of FDG-PET images, EEG dipoles and anatomical images (MRI) were applied to patients with drug-resistant epilepsy.Methods: Source location was determined using Brain Electromagnetic Source Analysis (BESA) program. The dipole location provided by BESA was then transformed into PET co-ordinates using the patient's MRI previously registered with the PET image. As a difference with other methods, no external markers are necessary.Results: The study group includes ten drug-resistant epileptic patients. FDG hypometabolism was found in all patients. Abnormalities in glucose uptake were always ipsilateral to the EEG dipole. However, quantitative analysis of FDG-PET within hypometabolic areas showed no significant correlation between decrease glucose uptake and location of EEG-dipole source. The comparison of the results using both methods shows that the dipole location matches the FDG-PET hypometabolic area for all the patients. Combining the spatial localization on FDG-PET with the temporal accuracy of EEG dipole source aids in the exact localization of the epileptogenic focus.Conclusion: As a conclusion, the results show that projection of EEG dipole data onto FDG-PET may play a key role in the indication of surgery for the treatment of drug-resistant epileptic patients, provided it is simple and easy to perform.     

经动脉钙剂刺激试验术前定位诊断胰岛素瘤的价值

目的：评价经动脉钙剂刺激试验对胰岛素瘤术前定位的诊断作用。方法：对16例临床颖为胰岛素胰腺B超和CT检查均阴性的患者，术前应用经动脉钙剂刺激肝静脉取血测定胰岛素（ASVS）的方法进行肿瘤定位。经各供胰动脉分别注射葡萄糖酸钙，在注射前及注射后30，60，90，120，150s分别取2ml肝静脉血测定胰岛素。动脉刺激后血胰岛素水平的峰值超过基础值2倍以上，则确定肿瘤位于该动脉供应的胰腺区域，结果：16例患者，手术和病理证实孤立胰岛素瘤12例和胰岛细胞增生1例，除1例胰岛素瘤外，ASVS对肿瘤均做出了准确定位，另3例经手术探查或随访排除胰岛素瘤，ASVS结果亦为阴性。因此ASVS术前定位胰岛素瘤或胰岛细胞增生的敏性为92．3％（12／13），特异性为100％（3／3），准确性为93．7％（15／16）。结论：经动脉钙剂刺激肝静脉取血测定胰岛素的方法安全准确，适用于其他影像学检查阴性的胰岛素瘤的术前定位。     

Selective Intra-Arterial Calcium Stimulation with Hepatic Venous Sampling for Preoperative Localization of Insulinomas

Objective

To determine the value of selective intra-arterial calcium stimulation with hepatic venous sampling using serum insulin and C-peptide gradients for the preoperative localization of insulinomas.

Materials and Methods

Seven consecutive patients [three men and four women aged 15-77 (mean, 42.7) years] with hypoglycemia underwent selective intra-arterial calcium stimulation in conjunction with hepatic venous sampling. Insulin gradients were calculated by an individual blinded to all other preoperative imaging studies and operative findings. In all patients except one, C-peptide gradients were also analyzed. The results were compared with the preoperative findings of ultrasonography, computed tomography, arteriography and endoscopic ultrasonography, as well as with the intraoperative findings of ultrasonography and palpation at surgery.

Results

Eight insulinomas (mean diameter, 12.5 mm) were diagnosed after surgery. In six patients, the calcium stimulation test with insulin gradients allowed accurate localization of the pathologic source of insulin secretion. Both C-peptide and insulin gradients substantially increased diagnostic accuracy. In one patient, C-peptide gradients were more helpful than insulin gradients for tumor localization.

Conclusion

Selective intra-arterial calcium stimulation with hepatic venous sampling is a highly accurate and safe method for the preoperative localization of insulinomas. Additional C-peptide gradients seem to be helpful in assessing tumor location, but further study is needed.     

Comparison and histopathological correlation of three parathyroid imaging methods in a population with a high prevalence of concomitant thyroid diseases

The aim of this prospective study was to evaluate the diagnostic utility of a technetium-99m sestamibi dual-phase protocol enhanced by single-photon emission tomography (SPET) and semiquantitative analysis in comparison to established preoperative staging procedures in patients with primary hyperparathyroidism. Twenty-eight (50%) out of 56 patients had superimposed thyroid disease, and 12 patients had previously undergone neck surgery. Visual and semiquantitative analysis of planar^99mTc-sestamibi dual-phase imaging, SPET of the delayed phase, ultrasonography, and thallium-201 chloride-technetium-99m pertechnetate subtraction scintigraphy was further correlated with the histopathological examination of the surgical specimens.^99mTc-sestamibi dual-phase imaging achieved the highest sensitivity for side localization and precise localization compared with²⁰¹Tl-^99mTc subtraction scintigraphy and ultrasonography, but the differences reached statistical significance only in comparison to ultrasonography. Semiquantitative analysis did not enhance sensitivity. Adenoma detection by^99mTc-sestamibi dual-phase imaging was only correlated to serum calcium levels and osteocalcin, not to cell density or oxyphil cell count (SPET yielded additional information for the exact topographical localization of the parathyroid tumour in 22 (39%) patients with superimposed thyroid disease or previous neck surgery but did not enhance the overall detection rate.     

99Tcm-MIBI SPECT/CT融合断层显像在甲状旁腺功能亢进症中的应用价值

目的评价99Tcm-MIBI SPECT/CT双时相融合断层显像在原发性甲状旁腺功能亢进症（PHPT）与继发性甲状旁腺功能亢进症（SHPT）中的应用价值。方法回顾性分析97例（PHPT 28例,SHPT 69例）HPT患者的99Tcm-MIBI SPECT/CT显像图像特征、症状、血清甲状旁腺激素（PTH）、血钙、磷及碱性磷酸酶（AKP）等结果。分析比较PHPT和SHPT两组患者的显像特点、手术病理、实验室检查以及诊断的灵敏度、特异度与临床指标之间的相关性。结果（1）99Tcm-MIBI SPECT/CT显像对PHPT的术前诊断灵敏度为96.55%,特异度为98.78%;对SHPT的术前诊断灵敏度为68.77%,特异度为79.17%。（2）PHPT多表现为单发病灶,而SHPT多表现为多个亢进的甲状旁腺病灶,病灶平均直径较小（Z=-2.591,P=0.010）,且容易合并钙化（χ2=9.588,P < 0.01）,差异均有统计学意义。（3）PHPT中无特殊不适主诉的患者比例明显高于SHPT中的比例（χ2=11.713,P < 0.001）,PHPT出现结石的比例高于SHPT（χ2=6.075,P < 0.001）,SHPT出现骨痛的比例高于PHPT（χ2=24.382,P < 0.01）,差异均有统计学意义;SHPT患者血清PTH和AKP水平均明显高于PHPT,差异有统计学意义（Z=-6.663、-4.326,均P < 0.001）,PHPT具有高钙低磷的特点,SHPT患者血钙正常或轻度升高,血磷明显升高。结论99Tcm-MIBI SPECT/CT双时相显像在PHPT患者的术前定位中有重要价值,特别是在PHPT中有极高的准确率。与PHPT相比,SHPT血清PTH、AKP水平升高更明显,多表现为多个病灶,病灶小,易合并钙化。     

Thallium-technetium subtraction scintigraphy of enlarged parathyroid glands after calcitonin stimulation of parathyroid hormone secretion.

To improve the sensitivity of thallium-technetium subtraction scintigraphy for preoperative localization procedure of enlarged parathyroid glands in primary hyperparathyroidism, we administered calcitonin intramuscularly 4 hours before the scintigraphy in 14 consecutive patients. Injection of calcitonin reduced plasma levels of ionized calcium from 1.47 +/- 0.10 mmol/l to 1.41 +/- 0.09 mmol/l (p less than 0.01). Concomitantly, serum levels of intact parathyroid hormone increased from 6.4 +/- 2.5 pmol/l to 7.9 +/- 2.6 pmol/l (p less than 0.001). The scintigram after calcitonin injection visualized 11 adenomas (sensitivity 78%) compared to only 9 (sensitivity 64%) in conventional scintigrams. In addition, 5 of the adenomas were more distinctly imaged in the scintigram after calcitonin injection, whereas in only one patient was the conventional scintigram better. Thus, the calcitonin injection improved the scintigram in 7 cases and was inferior in only one case (p = 0.031). We conclude that stimulation of parathyroid hormone secretion with calcitonin results in a better preoperative localization of enlarged parathyroid glands in primary hyperparathyroidism.     

Insulinomas: localization with selective intraarterial injection of calcium

To facilitate the noninvasive preoperative localization of islet cell tumors less than 15 mm in diameter, the authors examined the use of calcium as an insulin secretagogue in an arterial stimulation venous sampling (ASVS) technique. In four patients with episodic hypoglycemia, calcium gluconate (0.01-0.025 mEq Ca2+/kg) was injected directly into branches of the celiac plexus (gastroduodenal, splenic, and hepatic arteries) and the superior mesenteric artery. In all patients, serum levels of insulin rose abruptly in blood samples taken from the right hepatic vein 30 and 60 seconds after the infusion of calcium into the artery supplying the tumor; injection into an artery not supplying the tumor did not result in a similar rise. Accurate localization of the insulinomas was verified at surgery in three patients. In the fourth patient, who did not undergo surgery, arteriographic results were positive for insulinoma at the predicted site. On the basis of these results, the authors believe noninvasive ASVS may replace invasive portal venous sampling as the most effective method for the localization of occult insulinomas.     

继发性肾源性异位甲状旁腺功能亢进的介入栓塞治疗

目的探讨介入栓塞治疗继发性肾源性异位甲状旁腺功能亢进的有效性、安全性及可行性。 方法术前通过高频超声、^99mTc-MIBI甲状旁腺核素显像、增强CT或增强MRI检查评估异位甲状旁腺的解剖位置及动脉血供情况,采用介入栓塞的方式阻断其供血动脉,从而使其逐渐缺血坏死失去功能。 结果第1例患者的异位甲状旁腺通过介入栓塞治疗后,其甲状旁腺素（parathyroid hormone,PTH）水平迅速下降,血钙、血磷亦迅速下降,皮肤瘙痒、周身骨痛等临床症状明显缓解;第2例患者因供血动脉显示不清,加之术中难以配合,仅完成部分血管栓塞,其PTH、血钙、血磷等指标呈一过性下降,但最终疗效不佳。 结论介入栓塞治疗异位甲状旁腺是一种创伤小、操作简便、疗效相对可靠、安全性高的方法,成功的关键是术前明确定位及供血动脉,术中尽量完全栓塞其供血动脉,但其长期有效性尚需进一步评价。     

Preoperative parathyroid localization by superimposed iodine-131 toluidine blue and technetium-99m pertechnetate imaging

A new parathyroid scintigraphic localization study by a dual radioisotope technique using radioiodinated toluidine blue (RTB) for the parathyroids and 99mTc for thyroid imaging is presented. A simple RTB labeling procedure achieving 99% tagging of the 131I-TB was used. The RTB was found to be a highly specific parathyroid radiotracer, consequently enabling superimposition of the delineated thyroid gland over the RTB avid parathyroid foci without a need for subtraction of the thyroid or vascular background. Forty-six patients with primary hyperparathyroidism underwent scintigraphic study prior to cervical (41 patients) or mediastinal (5 patients) exploration and 67 pathological parathyroid glands (34 adenomas and 33 hyperplasias) were excised. On follow-up, serum calcium level returned to normal in all patients. Correlation of the scintigraphic results with the surgical findings disclosed a sensitivity of 93%, with a specificity of 80% and an overall accuracy of 87%. This new simplified and specific RTB scintigraphic method justifies its use as a routine procedure for preoperative parathyroid scintigraphic localization in primary hyperparathyroidism.     

Intraoperative nuclear guidance in benign hyperparathyroidism and parathyroid cancer

The success of parathyroid surgery is determined by the identification and removal of all hyperactive parathyroid tissue. Ectopic location of parathyroid tumours and fibrosis due to previous operations can cause failure of parathyroidectomy. Parathyroid tumours accumulate and retain 2-methoxyisobutylisonitrile (MIBI) labelled with technetium-99m. This study assesses the value of intra-operative localization of parathyroid tumours using a hand-held gamma detector in patients with hyperparathyroidism and parathyroid cancer. Twenty patients undergoing their first operations for hyperparathyroidism, 15 patients undergoing reoperations for either persistent or recurrent hyperparathyroidism and two patients with parathyroid cancer were studied. Radioactivity in the neck and the mediastinum was recorded by a gamma detector after administration of 370 MBq^99mTc-MIBI. Surgical findings and postoperative serum levels of calcium were documented. The sensitivity of the gamma detector in identifying parathyroid tumours was 90.5% in first parathyroidectomies, 88.9% in reoperations for either persistent or recurrent hyperparathyroidism and 100% in parathyroid cancer. One false-positive result was due to a thyroid nodule. Hypercalcaemia ceased in all but one patient postoperatively. It is concluded that employment of the gamma detector is to be advocated in first parathyroidectomies when a parathyroid tumour cannot be discovered, in reoperations for either persistent or recurrent hyperparathyroidism and in surgery for parathyroid cancer.     

Relevance of 99mTc-MIBI rest uptake, ejection fraction and location of contractile abnormality in predicting myocardial recovery after revascularization.

The aim of this study was to analyse the influence of rest technetium-99m-methoxy-isobutyl-isonitrile (99mTc-MIBI) uptake, left ventricular ejection fraction (EF) and dysfunctional location in the prediction of myocardial viability. Rest 99mTc-MIBI single photon emission computed tomography (SPECT) was analysed in 82 patients (59+/-9 years, 70 men, 12 women) with one or more segments showing severe hypokinesia, akinesia or dyskinesia who had undergone coronary revascularization. Before and within 3-6 months after the revascularization, gated blood pool scintigraphy was performed. In the post-revascularization control, contractile recovery was observed in 48.7% (155/318) of the segments with severe hypokinesia, akinesia or dyskinesia. Significant increases in sensitivity (53%, 72% and 91%, P<0.0001) and negative predictive value (62%, 68% and 79%, P = 0.01) were observed with decreasing rest uptake 99mTc-MIBI levels of 50%, 40% and 30%, respectively. The decrease in specificity was also significant (67%, 53% and 32%, P<0.0001). The negative predictive value was higher than the positive predictive value mainly in patients with EF < or = 0.35 and with anterior dysfunction. In logistic regression analysis, uptake levels and EF were independent variables that influenced sensitivity and specificity. The negative predictive value was influenced by EF and the positive predictive value only by dysfunctional location. This study suggests that the negative predictive value of 99mTc-MIBI SPECT is higher than the positive predictive value, mainly in patients with EF < or = 0.35, and that the rest uptake level, EF and dysfunctional location are factors that must be considered when results of 99mTc-MIBI SPECT are analysed.     

MRI及99Tcm-MIBI显像对甲状旁腺机能亢进症的诊断价值

目的：评价MRI及^99Tcm-甲氧基异丁基异腈（MIBI）显像在原发性甲状旁腺机能亢进症（PHT）中检出病理性腺体的临床价值。方法：25例经手术证实的PHT患者实行了术前定位MRI检查，若甲状旁腺部位发现可凝软组织肿物，其信号高于周围正常甲状腺，则认为是病理性甲状旁腺，其中23例同时进行了双时相99Tcm-MIBI显像，如早期相出现放射性浓聚区且延迟相持续存在则考虑为异常甲状旁腺，MRI和99Tcm-MIBI显像阅片结果与病理检查结果对照。结果：术中共发现39个异常甲状旁腺，包括19个腺瘤（18例），19个增生（6例）和1个上皮细胞癌（1例），MRI和99Tcm-MIBI显像对检出病理性腺体的准确性分别为84．1％和85．0％,但前者灵敏度（74．4％）高于后者（67．6％），而后者的特异性（97．8％）高于前者（91．8％），两种方法联合应用准确性提高到91．3％，灵敏度为91．2％，特异性为91．3％，结论：99Tcm-MIBI显像可作为继B超检查之后的首选术前定位检查法，但最理想的最联合应用MIR和99Tcm-MIBI显像。     

Evaluating the accuracy of perfusion/metabolism (SPET/PET) ratio in seizure localization

Mini-Abstract The uncoupling between brain perfusion and metabolism was evaluated as a potential tool for seizure localization by creating an interictal SPET divided by interictal PET functional ratio-image and by evaluating its sensitivity and specificity to areas subsequently surgically resected. The uncoupling between brain perfusion and metabolism was evaluated through the creation of a functional SPET/PET ratio-image relying on interictal single-photon emission computed tomography (SPET) and positron emission tomography (PET) scans in epilepsy patients. The uncoupling of these two physiological brain functions has been demonstrated to be a characteristic of epileptogenic tissue in temporal lobe epilepsy and could potentially serve as a diagnostic measure for localization of seizure onset areas in the brain. The accuracy of hemispheric localization, sensitivity, and specificity of perfusion to metabolism ratio-images were evaluated as compared to standard methods of PET reading. Methods Interictal HMPAO-SPET and FDG-PET scans were obtained from 21 patients who then went on to remain seizure free for a minimum of 1 year post surgical resection. Using Statistical Parametric Mapping (SPM2), the SPET and PET scans were spatially registered and spatially normalized to a standard template (geometric warping). A functional image was created by calculating the ratio of perfusion to metabolism. Discrete areas of uncoupling in the ratio-images were selected, quantified, and compared to visually interpreted PET readings as well as the actual site of subsequent surgical resection. Localization was determined by comparing the hemispheric location of these areas to sites of surgical resection. Sensitivity and specificity of ratio-images and PET readings were calculated by dividing the brains into four sections per hemisphere. Results When compared to known sites of successful surgical resection, the pre-surgical visually interpreted PET readings had a correct hemispheric localization in 69.6% of cases, while the regions of uncoupling selected in the pre-surgical ratio-images had a correct hemispheric localization of 82.6%. In addition, the regional sensitivity of visually interpreted PET readings was 63.0% with a specificity of 95.7%, while the sensitivity of the ratio-images was 68.0% with a specificity of 96.0%. Conclusion Compared to the PET readings, the ratio-images yielded similar sensitivity and specificity measures, but had an improved hemispheric localization. Hence, ratio-images may be a valuable diagnostic tool in the hemispheric localization, which could enhance the use of PET readings alone.     

The significance of calcific valvular heart disease in Tc-99m pyrophosphate myocardial infarction scanning: radiographic, scintigraphic, and pathological correlation.

Technetium-99m pyrophosphate (PPi) is currently considered the best scanning agent for the diagnosis of acute myocardial infarction. False-positive scans have been reported in association with unstable angina, alcoholic cardiomyopathy, and ventricular aneurysms. In this study, 86% of patients (12/14) with either calcific aortic or mitral valvular heart disease had positive PPi cardiac scintiscans and the location of the PPi uptake was limited to the calcific valve in all (9/9) of the patients who underwent valve replacement surgery. Six patients with valvular disease without radiologic evidence of calcium had negative PPi heart images. Three of these patients had surgical valve replacement, and in none was there increased uptake in the resected valve. Seventy-five percent of the patients with calcified aortic valves had localization of the PPi activity to the area of the aortic valve, whereas 50% of the patients with calcified mitral valves showed a diffuse pattern of uptake on the cardiac image. In vitro demonstration of increased radioactivity in surgically removed cardiac valves warrants the conclusion that Tc-99m PPi is taken up by calcified heart valves. We conclude that while PPi heart scanning is a sensitive indicator of acute myocardial infarction, false-positive scans can occur in the presence of calcific valvular disease, due to localization of PPi in the calcified portion of the valve.     

Acute massive gastrointestinal bleeding: detection and localization with arterial phase multi-detector row helical CT

PURPOSE: To prospectively evaluate accuracy of arterial phase multi-detector row helical computed tomography (CT) for detection and localization of acute massive gastrointestinal (GI) bleeding, with angiography as reference standard. MATERIALS AND METHODS: Institutional review board approved this study; written informed consent was obtained from each patient or patient's family after procedures, including radiation dose, were explained. Twenty-six consecutive patients (17 men, nine women; age range, 18-89 years) had acute massive GI bleeding (defined as requirement of transfusion of at least 4 units of blood during 24 hours in the hospital or as hypotension with systolic blood pressure <90 mm Hg) and underwent arterial phase multi-detector row CT before angiography. Scans were obtained during arterial phase to identify extravasation of contrast material with attenuation greater than 90 HU within bowel lumen; this finding was considered diagnostic for active GI bleeding. Presence of contrast medium extravasation in each anatomic location was recorded. Sensitivity, specificity, positive and negative predictive values, and accuracy of multi-detector row CT for detection of acute GI bleeding were assessed. Accuracy for localization of acute GI bleeding was assessed by comparing locations of active bleeding at both multi-detector row CT and angiography in each patient who had active bleeding. RESULTS: Arterial phase multi-detector row CT depicted extravasation of contrast material in 21 of 26 patients. Overall location-based sensitivity, specificity, accuracy, and positive and negative predictive values of multi-detector row CT for detection of GI bleeding were 90.9% (20 of 22), 99% (107 of 108), 97.6% (127 of 130), 95% (20 of 21), and 98% (107 of 109), respectively. Overall patient-based accuracy of multi-detector row CT for detection of acute GI bleeding was 88.5% (23 of 26). The location of contrast material extravasation on multi-detector row CT scans corresponded exactly to that of active bleeding on angiograms in all patients with contrast medium extravasation at both multi-detector row CT and angiography. CONCLUSION: Arterial phase multi-detector row CT is accurate for detection and localization of bleeding sites in patients with acute massive GI bleeding.     

Perfusion-based high-resolution functional imaging in the human brain at 7 Tesla.

Perfusion-based MRI measures cerebral blood flow (CBF) at the capillary level and can be used for functional studies based on the tight spatial coupling between brain activity and blood flow. Obtaining functional CBF maps with high spatial resolution is a major challenge because the CBF signal is intrinsically low and the SNR is critical. In the present work, CBF-based functional imaging was performed at a considerably smaller voxel size than previously reported in humans. High-resolution CBF maps were obtained with voxel sizes as small as 0.9 x 0.9 x 1.5 mm(3) in the human brain. High sensitivity was made possible by signal-to-noise gains at the high magnetic field of 7 T and by using a novel RF combination coil design. In addition, a reduction of the field-of-view was critical to achieve 0.9-mm in-plane resolution with gradient-echo echo-planar imaging in a single shot. Functional CBF data were compared with functional BOLD data to reveal that, for CBF, large contrast- to-noise gains were obtained at high spatial resolution, indicating that the functional CBF response was more localized. High-resolution functional CBF imaging is significant for neuroscience research because it provides better localization and more specific information than BOLD for monitoring brain function.     

Gastrointestinal bleeding: improved localization with cine scintigraphy.

Studies of gastrointestinal bleeding, done with technetium-99m-labeled red blood cells were performed in 52 consecutive patients to determine whether cinematic acquisition and display localized sites of bleeding more accurately than did conventional static imaging. Computerized images were obtained for 15 seconds per image in 15-minute sets. Interpretations based on a cinematic display were compared with those based on standard 1-minute images obtained every 5 minutes. Pathologic confirmation of a site of bleeding was obtained in 21 patients. The cinematic display demonstrated bleeding not seen on static images and yielded either more accurate localization or increased sensitivity in eight of 21 patients (38%). Linear regression showed that the cinematic correlation (r = .98) to the actual site of bleeding was better than either of two readers' interpretations of the static display (r = .93, P less than .02; and r = .88, P less than .0004). The mean error for cinematic localization of bleeding (0.4 anatomic segments +/- 0.6 [standard deviation]) was less than that for the static interpretations (1.1 anatomic segments +/- 1.4) (P less than .01). It is concluded that computerized cinematic acquisition and display of scintigrams improves localization and detection of gastrointestinal bleeding.