Effects of temperature increase during surgical drilling in acrylic resin.

BACKGROUND: Acrylic resin is employed for drilling bone biomodels. Since drilling causes temperature rise, the mechanical properties of thermoplastic acrylic resin can be altered, consequently affecting drilling properties. However, it is currently unclear how this temperature increase impacts drilling. OBJECTIVE: This study reports the effects of temperature rise on both mechanical and drilling properties through experiments in which acrylic resin is drilled under machining conditions employed in surgical operations. METHODS: Drilling tests were performed using a surgical drill on medical acrylic resin under dry conditions to observe generated cutting chips and measure drilling properties such as torque, drilling time, and temperature rise. Dynamic mechanical analysis measurements were performed to consider temperature effects. RESULTS: According to the morphological classification of the cutting chips, the drilling process is divided into three phases corresponding with the generation of cylindrical helix, waved, and rounded nubby chips respectively. During drilling, the temperature of the chips can exceed the glass transition temperature (100∘C) resulting in decreased viscoelasticity, which is associated with decreased torque. CONCLUSIONS: While drilling acrylic resin under surgical machining conditions, increasing temperature can decrease torque and morphologically change cutting chips due to the decrease in mechanical properties above the glass transition temperature.

[Detection of the sentinal node in squamous-cell carcinoma of the oral cavity and oropharynx. Preliminary study]. / Détection du ganglion sentinelle dans les carcinomes épidermoïdes de la cavité buccale et de l'oropharynx. Etude préliminaire.

INTRODUCTION: The sentinel lymph node is defined as the first relay of the lymphatic drainage of the tumor. Isotopic detection of the sentinel lymph node and absence of its metastatic invasion should theoretically be predictive of total drainage of the tumor. The goal of this study was to evaluate sentinel lymph node detectability by lymphoscintigraphy in N0 and/or N1 squamous-cell carcinoma of oral cavity and oropharynx and to determine its negative predictive value. MATERIAL AND METHOD: Lymphoscintigraphy was used for sentinel lymph node detection. The procedure required peritumoral injection of technicium-labeled colloids to enable anatomical and cutaneous location of the sentinel lymph node. A one-way Tyco-Mallinckrodt probe was used for intraoperative detection of the sentinel lymph node. This prospective study included 21 patients with N0 or N1 squamous-cell carcinoma of the oral cavity and the oropharynx. The surgical attitude based on T and N was not modified in this prospective study without direct individual benefit for the patient. Neck dissection was achieved without difficulty. RESULTS: The sentinel lymph node was identified in 20 out of 21 subjects. The sentinel lymph node was not identified in one patient with recurrence T2N0M0 squamous-cell carcinoma of the oropharynx radiated 3 years earlier. The percentage of false-negatives was 12.5% (1 false-negative out of 8 positive patients), giving a sensibility of the detection method of 87.5% (IC (95%)=[47.35-99.68]). This false-negative patient had a T3N0M0 squamous-cell carcinoma of the oropharynx with a sentinel lymph node removed in territory III. Neck dissection revealed 1 N + R- in the sub-mandibular territory associated with 27 N-R-. The probability of not finding a metastatic node at neck dissection when the sentinel lymph node is not metastatic (negative predictive value) was 92.3% (12/13) (IC (95)=[63.97-99.81]). The specificity of the method was 100%, as was the positive predictive value, because no sentinel node was diagnosed positive wrongly on frozen sections among patients without true histological node metastasis. DISCUSSION: For routine care of patients with squamous-cell carcinoma of the oral cavity and the oropharynx detection of the sentinel lymph node is proposed primarily for patients with T1T2N0 staging. Larger tumors can modify the architecture and flow within the lymphatic ducts, and consequently even the concept of a sentinel lymph node. Systematic neck dissection is required or T3T4, even when N0. Our series of T1T2N0 tumors is too small to enable statistically significant conclusions. A low level of false-negative in a larger series would be necessary to propose this technique instead of convention neck dissection for T1T2 tumors of the oral cavity and oropharynx.

Influence of short-chain fatty acids on iron absorption by proximal colon.

BACKGROUND: Short-chain fatty acids produced by bacterial fermentation in the colon enhance the local absorption of cations, such as calcium, that could be used to improve the bioavailability of iron if a significant colonic absorption of iron were to occur. METHODS: Iron (iron gluconate, 100 microM) absorption by the caecum of the rat was compared with that in proximal sites of the small bowel using the Ussing chamber model; the influence of probiotic bacteria (Propionibacterium freudenreichii) on iron absorption was assessed and compared with that of two of their fermentation products (acetic and propionic acids) using the Ussing chamber and the ligated colon with gamma emitting iron as experimental models. RESULTS: The caecum absorbed less iron than the duodenum, but significantly more than the jejunum and ileum. This occurred mainly through an enhanced mucosal transfer of iron uptake. Propionibacteria enhanced iron absorption from the proximal colon; the same effect was observed in the presence of viable bacteria, or the culture medium free of viable bacteria, or acetate and propionate or propionate alone. CONCLUSIONS: The proximal colon could be a significant site available for iron absorption; this absorption can be enhanced by local production of short-chain fatty acids such as propionate.

Non-invasive grading of oligodendrogliomas: correlation between in vivo metabolic pattern and histopathology.

Several studies have shown that the prognosis of oligodendrogliomas is dependent on their histological grade. In order to identify a non-invasive method for the primary diagnosis and follow-up of these tumours, we investigated the relationship between their in vivo metabolism, assessed by positron emission tomography (PET), and their histological grade assessed at the same time. Forty-seven patients with histologically confirmed oligodendrogliomas were investigated. Conventional neuroradiological assessment by computed tomography and magnetic resonance imaging (MRI) was performed in all the patients. All the histology slices were reviewed by the same pathologist after referral from various pathology laboratories. The PET investigation included a carbon-1 methionine (11C-MET) uptake study and, in the majority of cases, a fluorine-18 fluorodeoxyglucose (18F-FDG) uptake study, in order to investigate at the same time both amino acid metabolism and glycolysis. The sampled tumour region of interest (ROI) was defined from the T1-weighted 3D MR scan matched with the PET scan. Tracer concentration in each voxel of the tumour ROI was divided by the mean concentration in an ROI of the same size located in the healthy brain tissue. For each tumour and each tracer, we characterized the metabolic pattern on the basis of the mean and the maximum tumour to healthy tissue concentration ratio, and also the standard deviation and range of the ratios, which indicate the degree of metabolic heterogeneity of the tumour. The histological criteria for differentiating between high- and low-grade tumours were those of the WHO and, partially, of the Sainte-Anne-Daumas-Duport classification. Highly significant differences between high- and low-grade oligodendrogliomas (Mann-Whitney test: P<0.0001) were observed for all the assessed parameters of 11C-MET uptake. On the other hand, the pattern of 18F-FDG uptake showed only moderate differences between the two tumour groups.

Improvement of cardiac neuronal function after carvedilol treatment in dilated cardiomyopathy: a 123I-MIBG scintigraphic study.

UNLABELLED: Carvedilol can induce important clinical and hemodynamic improvements in patients with chronic heart failure resulting from severe left ventricular (LV) dysfunction. This study examines the impact of carvedilol on cardiac neuronal function using 123I-metaiodobenzylguanidine (MIBG) scintigraphy in dilated cardiomyopathy. METHODS: Twenty-two patients with chronic heart failure (19 men, 3 women; mean age, 54 y; age range, 34-64 y) assessed as New York Hospital Association (NYHA) class II or III and with initial resting radionuclide LV ejection fractions (LVEF) < 0.40 were enrolled in the study. Patients had long histories of symptomatic LV dysfunction despite optimal diuretics and angiotensin-converting enzyme inhibitor treatment. Over a 6-mo period, 50 mg/day carvedilol was administered to these patients. Planar 123I-MIBG scintigraphy provided measurements of cardiac neuronal uptake (as heart-to-mediastinum count activity ratio [HMR]), 4h after intravenous injection of 185 MBq MIBG. Hemodynamic, clinical, radionuclide LVEF and HMR data measured at the outset and after 6 mo of carvedilol were compared. RESULTS: Resting heart rate decreased from 81 +/- 13 to 71 +/- 9 bpm (P = 0.003). After carvedilol therapy NYHA functional classification for these patients improved from 2.6 +/- 0.5 to 2.3 +/-0.5 (P = 0.04), LVEF improved from 22% +/- 9% to 30% +/- 13% (P = 0.005), and HMR improved from 145% +/- 23% to 170% +/- 25% (P = 0.0001). CONCLUSION: Carvedilol induces improvements of clinical symptoms and cardiac neuronal and systolic functions in patients with dilated cardiomyopathy and chronic optimal treatment.

Impairment of cardiac neuronal function in childhood dilated cardiomyopathy: an 123I-MIBG scintigraphic study.

UNLABELLED: Abnormalities of norepinephrine uptake have been found to reflect impairment of cardiac adrenergic neuronal function in adults with heart failure. To our knowledge, no data on childhood dilated cardiomyopathy (DCM) are available. The aim of this study was to assess the cardiac neuronal function using 123I-metaiodobenzylguanidine (MIBG) scintigraphy in children with idiopathic DCM. METHODS: We studied 26 patients (mean age, 44+/-50 mo) with DCM and left ventricular dysfunction and 12 control subjects (mean age, 49+/-65 mo) with normal left ventricular function. All subjects underwent planar cardiac imaging after intravenous injection of 20-75 MBq 123I-MIBG. A static anterior view was acquired 4 h after injection. The heart-to-mediastinum count ratio was measured as described previously. RESULTS: On the basis of a reduction of the heart-to-mediastinum count ratio, cardiac neuronal uptake of 123I-MIBG was significantly decreased in patients with DCM compared with cardiac uptake in control subjects (172%+/-34% versus 277%+/-14%; P<0.0001). A significant correlation was found between left ventricular ejection fraction and 123I-MIBG cardiac uptake in patients with DCM (y = 2.5x + 113.3; r = 0.80; P<0.0001). CONCLUSION: Cardiac adrenergic neuronal function is impaired in children with idiopathic DCM. 1231-MIBG cardiac scintigraphy is a useful tool to assess cardiac neuronal function in childhood DCM.

Predictive value of (99m)Tc-HMPAO-SPECT for neurological Outcome/Recovery at the acute stage of stroke.

BACKGROUND AND PURPOSE: Combined perfusion and oxygen metabolism PET imaging is highly predictive of spontaneous outcome after middle cerebral artery (MCA) stroke, independent of clinical scores, but whether the assessment of perfusion alone by SPECT provides similar information remains unclear. We have assessed the prognostic value of (99m)Tc-HMPAO-SPECT at the acute stage of stroke. METHODS: Twenty-seven first-ever nonhemorrhagic MCA territory stroke patients were prospectively studied 4-20 h (mean: 12 h) after onset with (99m)Tc-HMPAO-SPECT. None was part of a therapeutic trial or received thrombolysis. Neurological deficits were quantified at admission and 2 months later with Orgogozo's MCA scale. SPECT images were visually classified by 3 independent observers into one of three patterns, as follows: pattern I = marked and extensive tracer hypofixation; pattern II = moderate and/or focal hypofixation with or without combined hyperfixation, and pattern III = normal or increased uptake without hypofixation. In addition to this visual analysis, we also calculated a voxel-based 'hypoperfusion score', an index of severity x extent of hypofixation according to Mountz's method. RESULTS: There was a good intra- and interobserver agreement. After consensus, 9, 14 and 4 patients were classified in patterns I, II and III, respectively. These patterns had a significant predictive value for raw outcome but not for percentage recovery (p = 0.008 and p = 0.127, respectively). Thus, all patients in pattern III had a good outcome, while most (but not all) patients in pattern I had a poor or intermediate outcome; pattern II patients were more evenly distributed among outcomes. Hypoperfusion scores were highly significantly positively correlated with both 2-month outcomes and percentage recoveries, even after controlling the predictive value of day 0 MCA scores by partial correlations. COMMENTS: We found that SPECT had a significant added predictive value even when compared to admission neurological scores. Although less accurate than PET, (99m)Tc-HMPAO-SPECT may help to predict spontaneous individual neurological evolution, especially whenever perfusion images are normal or show an increased tracer uptake without associated hypofixation.

The reversibility of cardiac neuronal function after removal of a pheochromocytoma: an I-123 MIBG Scintigraphic Study.

PURPOSE: Twelve patients with proved pheochromocytoma evaluated in our institution between 1991 and 1997 are described. METHODS: The patients' urinary excretion rates and their metabolites (vanylmandelic acid and metanephrines) were significantly greater than normal before surgery. Echocardiography showed normal left ventricular ejection fractions (72% +/- 8%). All of the patients underwent planar I-123 metaiodobenzylguanidine (MIBG) scintigraphy to assess cardiac neuronal uptake 4 hours after and locate a pheochromocytoma 24 hours after intravenous injection of 185 MBq (3 mCi) I-231 MIBG. Ten patients with pheochromocytoma had positive tumoral findings with I-123 MIBG scintigraphy. Twelve patients had significant impairment of cardiac neuronal uptake of MIBG, with a heart:mediastinum ratio averaging 142% +/- 18% (normal value, 230% +/- 30%, P < 0.05). Postoperative cardiac MIBG imaging was performed in all patients (at 6 +/- 3 months). RESULTS: After surgical removal of the pheochromocytoma, cardiac MIBG uptake and the heart:mediastinum uptake ratios improved significantly (197% +/- 20%, P < 0.05) in all the patients. Urinary excretion rates and metabolites returned to the normal range. However, no significant correlation was found between cardiac MIBG uptake and urinary excretion rates and metabolites after the tumors were removed. CONCLUSION: Removing a pheochromocytoma reversed cardiac neuronal function as assessed by MIBG scintigraphy.

Detection of cardiac myxoma by F-18 FDG PET.

Intracardiac tumors occur infrequently and are difficult to diagnose with CT and MRI. The authors describe the successful imaging of a right atrial myxoma with F-18 FDG PET.

Impairment of cardiac neuronal function in acute myocarditis: iodine-123-MIBG scintigraphy study.

UNLABELLED: Abnormalities of norepinephrine uptake have been found to reflect impairment in adrenergic nerve function that has influenced the cardiac outcome of patients with heart failure. The aim of this study was to explore the cardiac neuronal function by using 123I-metaiodobenzylguanidine (MIBG) scintigraphy in patients with acute myocarditis. METHODS: We studied 15 patients (age range 42 +/- 10 yr) with clinical, biological, electrocardiographic and radionuclide left ventricular ejection fraction (LVEF) (41% +/- 7%) data indicating myocarditis and 10 normal subjects (age range 36 +/- 7 yr, mean radionuclide LVEF 69% +/- 8%, p < 0.05). Fourteen patients had positive histologic findings of myocarditis and 1 had nonspecific histological data. All patients underwent planar cardiac imaging after intravenous injection of 185 MBq 123I-MIBG and right ventricular biopsy within 7 days. A chest anterior view was acquired 4 hr later. Heart-to-mediastinum ratio activity was measured, as previously described in our laboratory. RESULTS: Significant impairment of cardiac neuronal uptake of MIBG was observed and based on a reduction of heart-to-mediastinum ratio (148% +/- 16% versus 234% +/- 36%, p < 0.05). A significant correlation was observed between LVEF and MIBG uptake in patients (y = 1.58x +/- 83.7, r = 0.72, p < 0.01). CONCLUSION: Acute myocarditis is associated with an injury of the cardiac adrenergic neuronal function. In addition to the inflammatory injury of the myocytes, the impairment of adrenergic function may be involved in the cardiac pump failure induced by myocarditis.

Iodine-123-metaiodobenzylguanidine SPECT of regional cardiac adrenergic denervation in Brugada syndrome.

We present the case of 44-yr-old man who presented syncope with ventricular tachycardia in the setting of Brugada syndrome. In addition to the electrocardiographic evidence of the syndrome and the absence of apparent structural heart disease, clear defects of myocardial neuronal metaiodobenzylguanidine (MIBG) uptake on MIBG SPECT imaging also were found in inferior, apical and septal walls. Thallium-201 SPECT distribution was homogeneous along the left ventricle. Thus, cardiac MIBG scintigraphy provides information about left ventricular dysinnervation in a patient with Brugada syndrome, enhancing the clinical utility of myocardial MIBG SPECT imaging in life-threatening ventricular arrhythmias.

Impact of exercise rehabilitation on cardiac neuronal function in heart failure: an iodine-123 metaiodobenzylguanidine scintigraphy study.

Exercise training can induce important haemodynamic and metabolic adaptations in patients with chronic heart failure due to severe left ventricular dysfunction. This study examined the impact of exercise rehabilitation on cardiac neuronal function using iodine-123 metaiodobenzylguanidine (MIBG) scintigraphy, Fourteen patients (11 men, 3 women; mean age 48 years; range: 36-66 years) with stable chronic heart failure of NYHA class II-III and an initial resting radionuclide left ventricular ejection fraction (LVEF) < 50% were enrolled in the study. Patients underwent progressive, supervised endurance training (treadmill test, Bruce protocol) during a 6-month period (60 sessions, 3 sessions per week) at a cardiac rehabilitation referral centre in order to measure exercise parameters. Planar 123I-MIBG scintigraphy provided measurements of cardiac neuronal uptake (heart-mediastinum ratio activity, 4 h after intravenous injection of 185 MBq of MIBG). Radionuclide LVEF was also assessed at the outset and after 6 months of exercise training. Workload (801 +/- 428 vs 1229 +/- 245 kpm.min-1, P = 0.001), exercise duration (504 +/- 190 vs 649 +/- 125 s, P = 0.02), and myocardial MIBG uptake (135% +/- 19% vs 156% +/- 25%, P = 0.02) increased significantly after rehabilitation. However, LVEF did not change significantly (23% +/- 9% vs 21% +/- 10%, p = NS). It is concluded that exercise rehabilitation induces improvement of cardiac neuronal function without having negative effects on cardiac contractility in patients with stable chronic heart failure.

Comparative quantitation of cerebral blood volume: SPECT versus PET.

UNLABELLED: Quantification of cerebral blood volume (CBV) measured by SPECT has been used for evaluation of cerebral hemodynamics in patients with cerebrovascular diseases. The accuracy of such quantification, however, has not been validated with PET. METHODS: CBV was assessed using SPECT and in vitro 99mTc-labeled red blood cells and PET with the 15O steady-state inhalation method and C15O. In 23 patients with carotid artery disease, we measured hemispheric (including cortical and subcortical areas) CBV, and in 11 patients, we measured regional CBV in small cortical regions. We further evaluated the interhemispheric and inter-regional asymmetry of CBV with both methods. RESULTS: Quantitative values of both hemispheric and regional CBV measured by SPECT were significantly correlated with those measured by PET in the same patients. There was a significant correlation between the side-to-side asymmetry of CBV for both methods. CONCLUSION: This study demonstrates usefulness and the accuracy of SPECT for quantitative CBV assessment in comparison with the less widely available PET procedures.

[Value of cardiac scintigraphy with I123 meta-iodobenzylguanidine in congestive heart failure. A review]. / Valeur de la scintigraphie cardiaque a la 123I-méta-iodo-benzylguanidine dans l'insuffisance cardiaque congestive. Mise au point.

Heart failure is accompanied by major disturbances of the functioning of the sympathetic nervous system: global overactivation and local modifications of the adrenergic system. 123I-MIBG cardiac scintigraphy is an isotope technique investigating presynaptic adrenergic function. The cardiac uptake of MIBG is decreased during heart failure, reflecting a reduction of norepinephrine reuptake by cardiac presynaptic nerve endings. Alteration of presynaptic function occurs early and plays an important role in the pathogenesis of the deterioration of heart failure. 123I-MIBG cardiac scintigraphy allows in vivo assessment of the myocardial adrenergic reserves of patients with congestive heart failure. It should be proposed in all patients with severe ventricular dysfunction to help define the indications for heart transplantation.

Intravenous aminohydroxypropylidene bisphosphonate does not modify 99mTc-hydroxymethylene bisphosphonate bone scintigraphy. A prospective study.

Bisphosphonates have marked affinity for bone that makes them useful in both the treatment and imaging of bone lesions. Bone scintigraphy is very sensitive for the detection of bone metastases, which can cause life-threatening hypercalcemia requiring emergency treatment. This prospective study was done to determine whether intravenous administration of pamidronate, a second-generation bisphosphonate used to treat hypercalcemia, affects the affinity of the radiopharmaceutical 99m technetium-labeled hydroxymethylene bisphosphonate (99mTc-HMDP) for bone and bone lesions. Six patients with metastatic bone disease and five with Paget's disease of bone had a 99mTc-HMDP bone scan before and two to four days after an intravenous infusion of pamidronate. The number and activity of metastatic bone lesions were unchanged after pamidronate, even when the second bone scan was done only 24 hours after the pamidronate infusion. Our data suggest that emergency treatment of life-threatening hypercalcemia by intravenous pamidronate does not decrease the sensitivity of subsequent bone scanning done to detect bone metastases.

Assessment of portal contribution to liver perfusion by quantitative sequential scintigraphy and Doppler ultrasound in alcoholic cirrhosis. Diagnostic value in the detection of portal hypertension.

To assess the portal contribution to liver perfusion, we carried out quantitative sequential scintigraphy in 110 patients with alcoholic cirrhosis (22 Child-Pugh class A, 39 class B, 49 class C) and 15 normal subjects. Duplex Doppler ultrasound found a type of intrahepatic circulation that made the standard scintigraphic procedure inaccurate in four cases of cirrhosis, which were reevaluated. Portal contribution to liver perfusion was lower in cirrhotics than in normal subjects (48.7 +/- 29% versus 78.4 +/- 6%; p < 0.001). The sensitivity of scintigraphy in detecting portal hypertension, based on portal contribution < or = 66%, was 61.8% (with a 100% specificity) compared with 66.7% for endoscopy (diagnosis based on existence of varices). The overall sensitivity of the two tests together was 86.1%. Portal contribution to liver perfusion was inversely correlated to Child-Pugh score (r = 0.53; p < 0.001), to prothrombin time (r = 0.52; p < 0.001), and to hepatic venous pressure gradient (r = 0.43; p < 0.001) and positively correlated to albuminemia (r = 0.42; p < 0.001). Concurrent alcoholic hepatitis and the existence of large portosystemic collaterals were related to a decrease in portal contribution to liver perfusion. We conclude that quantitative sequential scintigraphy, which shows a direct relationship between portal contribution to liver perfusion, on the one hand, and the amount of portosystemic shunting, the progression of liver disease, and/or acute liver injury, on the other, could serve as a diagnostic test for portal hypertension. The addition of scintigraphy improves the overall sensitivity of endoscopy.

Right motor neglect associated with dynamic aphasia, loss of drive and amnesia: case report and cerebral blood flow study.

A 30-year-old right-handed man had right motor neglect, amnesia, aphasia and loss of drive following bilateral thalamic and subthalamic infarctions. Serial resting cerebral blood flow (CBF) measurements with either Xenon 133 inhalation or positron emission tomography at 1, 8 and 10 months post-onset showed a widespread and long-lasting low CBF in the cortex. An additional CBF measurement, during motor tasks, showed a marked interhemispheric asymmetry in the pattern of activation: whereas left hand movement resulted in a CBF increase in contralateral superior rolandic and prerolandic areas, no significant regional CBF changes were seen during right hand movement, despite recovery from motor neglect. This loss of CBF increase in cortical motor and premotor areas during voluntary movement of the previously neglected side points to a disruption of cortico-subcortical pathways subserving motor activation. The pathophysiology of aphasia, loss of drive and amnesia as well as their relationships to motor neglect, may also be discussed on the basis of thalamo-cortical disconnections.

[Value of hepatic angioscintigraphy combined to pulsed Echo-Doppler: application to the study of portal hypertension of cirrhotic patients. Apropos of 148 cases]. / Intérêt de l'angioscintigraphie hépatique couplée à l'écho-Doppler pulsé: application à l'étude de l'hypertension portale du sujet cirrhotique. A propos de 148 cas.

Quantitative hepatic angioscintigraphy was combined with duplex Doppler in order to study liver perfusion in normal subjects and in 148 patients with liver cirrhosis. The portal component of liver perfusion determined by scintigraphy was reduced in patients with liver cirrhosis and correlated to the development of cirrhosis and to porto-hepatic gradient pressure. Duplex Doppler allowed assessment of portal blood direction. Determination of portal blood flow was possible in only a few patients: portal blood flow was increased in the first stage of cirrhosis and then decreased; hepatofugal flow was observed only in the most severe stage. Angioscintigraphy and Duplex Doppler appear to be complementary in the study and follow-up of portal hypertension.