Determinants of kinetic energy of blood flow in the four-chambered heart in athletes and sedentary controls.

The kinetic energy (KE) of intracardiac blood may play an important role in cardiac function. The aims of the present study were to 1) quantify and investigate the determinants of KE, 2) compare the KE expenditure of intracardiac blood between athletes and control subjects, and 3) quantify the amount of KE inside and outside the diastolic vortex. Fourteen athletes and fourteen volunteers underwent cardiac MRI, including four-dimensional phase-contrast sequences. KE was quantified in four chambers, and energy expenditure was calculated by determining the mean KE/cardiac index. Left ventricular (LV) mass was an independent predictor of diastolic LVKE (R(2) = 0.66, P < 0.001), whereas right ventricular (RV) end-diastolic volume was important for diastolic RVKE (R(2) = 0.76, P < 0.001). The mean KE/cardiac index did not differ between groups (control subjects: 0.53 ± 0.14 mJ·l(-1)·min·m(2) and athletes: 0.56 ± 0.21 mJ·l(-1)·min·m(2), P = 0.98). Mean LV diastolic vortex KE made up 70 ± 1% and 73 ± 2% of total LV diastolic KE in athletes and control subjects (P = 0.18). In conclusion, the characteristics of the LV as a pressure pump and the RV as a volume pump are demonstrated as an association between LVKE and LV mass and between RVKE and end-diastolic volume. This also suggests different filling mechanisms where the LV is dependent on diastolic suction, whereas the RV fills with a basal movement of the atrioventricular plane over "stationary" blood. Both groups had similar energy expenditure for intracardiac blood flow, indicating similar pumping efficiency, likely explained by the lower heart rate that cancels the higher KE per heart beat in athletes. The majority of LVKE is found within the LV diastolic vortex, in contrast to earlier findings.

Quantification of left and right ventricular kinetic energy using four-dimensional intracardiac magnetic resonance imaging flow measurements.

We aimed to quantify kinetic energy (KE) during the entire cardiac cycle of the left ventricle (LV) and right ventricle (RV) using four-dimensional phase-contrast magnetic resonance imaging (MRI). KE was quantified in healthy volunteers (n = 9) using an in-house developed software. Mean KE through the cardiac cycle of the LV and the RV were highly correlated (r(2) = 0.96). Mean KE was related to end-diastolic volume (r(2) = 0.66 for LV and r(2) = 0.74 for RV), end-systolic volume (r(2) = 0.59 and 0.68), and stroke volume (r(2) = 0.55 and 0.60), but not to ejection fraction (r(2) < 0.01, P = not significant for both). Three KE peaks were found in both ventricles, in systole, early diastole, and late diastole. In systole, peak KE in the LV was lower (4.9 ± 0.4 mJ, P = 0.004) compared with the RV (7.5 ± 0.8 mJ). In contrast, KE during early diastole was higher in the LV (6.0 ± 0.6 mJ, P = 0.004) compared with the RV (3.6 ± 0.4 mJ). The late diastolic peaks were smaller than the systolic and early diastolic peaks (1.3 ± 0.2 and 1.2 ± 0.2 mJ). Modeling estimated the proportion of KE to total external work, which comprised ∼0.3% of LV external work and 3% of RV energy at rest and 3 vs. 24% during peak exercise. The higher early diastolic KE in the LV indicates that LV filling is more dependent on ventricular suction compared with the RV. RV early diastolic filling, on the other hand, may be caused to a higher degree of the return of the atrioventricular plane toward the base of the heart. The difference in ventricular geometry with a longer outflow tract in the RV compared with the LV explains the higher systolic KE in the RV.

Isolated pulmonary regurgitation causes decreased right ventricular longitudinal function and compensatory increased septal pumping in a porcine model.

AIM: Longitudinal ventricular contraction is a parameter of cardiac performance with predictive power. Right ventricular (RV) longitudinal function is impaired in patients with free pulmonary regurgitation (PR) following corrective surgery for Tetralogy of Fallot (TOF). It remains unclear whether this is a consequence of the surgical repair, or whether it is inherent to PR. The aim of this study was to assess the relationship between longitudinal, lateral and septal pumping in a porcine model of isolated PR. METHODS: Piglets were divided into a control (n = 8) group and a treatment (n = 12) group, which received a stent in the pulmonary valve orifice, inducing PR. After 2-3 months, animals were subjected to cardiac magnetic resonance imaging. A subset of animals (n = 6) then underwent percutaneous pulmonary valve replacement (PPVR) with follow-up 1 month later. Longitudinal, lateral and septal contributions to stroke volume (SV) were quantified by measuring volumetric displacements from end-diastole to end-systole in the cardiac short axis and long axis. RESULTS: PR resulted in a lower longitudinal contribution to RV stroke volume, compared to controls (60.0 ± 2.6% vs. 73.6 ± 3.8%; P = 0.012). Furthermore, a compensatory increase in septal contribution to RVSV was observed (11.0 ± 1.6% vs. -3.1 ± 1.5%; P < 0.0001). The left ventricle (LV) showed counter-regulation with an increased longitudinal LVSV. Changes in RV longitudinal function were reversed by PPVR. CONCLUSION: These findings suggest that PR contributes to decreased RV longitudinal function in the absence of scarring from cardiac surgery. Measurement of longitudinal RVSV may aid risk stratification and timing for interventional correction of PR in TOF patients.

Regional contribution to ventricular stroke volume is affected on the left side, but not on the right in patients with pulmonary hypertension.

To develop more sensitive measures of impaired cardiac function in patients with pulmonary hypertension (PH), since detection of impaired right ventricular (RV) function is important in these patients. With the hypothesis that a change in septal function in patients with PH is associated with altered longitudinal and lateral function of both ventricles, as a compensatory mechanism, we quantified the contributions of these parameters to stroke volume (SV) in both ventricles using cardiac magnetic resonance (CMR). Seventeen patients (10 females) evaluated for PH underwent right heart catheterization (RHC) and CMR. CMR from 33 healthy adults (13 females) were used as controls. Left ventricular (LV) atrioventricular plane displacement (AVPD) and corresponding longitudinal contribution to LVSV was lower in patients (10.8 ± 3.2 mm and 51 ± 12 %) compared to controls (16.6 ± 1.9 mm and 59 ± 9 %, p < 0.0001 and p < 0.01, respectively). This decrease did not differ in patient with ejection fraction (EF) >50 % and <50 % (p = 0.5) and was compensated for by increased LV lateral contribution to LVSV in patients (49 ± 13 % vs. 37 ± 7 %, p = 0.001). Septal motion contributed less to LVSV in patients (5 ± 8 %) compared to controls (8 ± 4 %, p = 0.05). RV AVPD was lower in patients (12.0 ± 3.6 mm vs. 21.8 ± 2.2 mm, p < 0.0001) but longitudinal and lateral contribution to RVSV did not differ between patients (78 ± 17 % and 29 ± 16 %) and controls (79 ± 9 % and 31 ± 6 % p = 0.7 for both) explained by increased RV cross sectional area in patients. LV function is affected in patients with PH despite preserved global LV function. The decreased longitudinal contribution and increased lateral contribution to LVSV was not seen in the RV, contrary to previous findings in patients with volume loaded RVs.

Prospective investigation of positron emission tomography in lung nodules.

PURPOSE: Solitary pulmonary nodules (SPNs) are commonly identified by chest radiographs and computed tomography (CT). Biopsies are often performed to evaluate the nodules further. An accurate, noninvasive diagnostic test could avoid the morbidity and costs of invasive tissue sampling. We evaluated the ability of fluorine-18 deoxyglucose positron emission tomography (FDG-PET) to discriminate between benign and malignant pulmonary nodules in a prospective, multicenter trial. METHODS: Eighty-nine patients who had newly identified indeterminate SPNs on chest radiographs and CT were evaluated with FDG-PET. PET data were analyzed semiquantitatively by calculating standardized uptake values (SUVs) as an index of FDG accumulation and also by a visual scoring method. PET results were compared with pathology results. RESULTS: Sixty SPNs were malignant and 29 were benign. Using SUV data, PET had an overall sensitivity and specificity for detection of malignant nodules of 92% and 90%. Visual analysis provided a slightly higher, but not statistically significant, sensitivity of 98% and lower specificity of 69%. For SPNs < or = 1.5 cm (34 of 89), the sensitivity and specificity of SUV and visual analysis were 80% and 95% and 100% and 74%, respectively. CONCLUSION: FDG-PET can accurately characterize indeterminate SPNs. PET imaging provides a noninvasive method to evaluate indeterminate SPNs, which can reduce the need for invasive tissue biopsy.

Intravenous DSA and duplex sonography as screening examinations for carotid disease: comparison in 102 vessels.

Duplex sonography and intravenous digital subtraction angiography (DSA) were compared in 102 carotid bifurcations in 51 patients. Sonograms were adequate in 87 (85%) vessels and angiograms were adequate on at least one view in 86 (84%) vessels. An adequate image was obtained by one or the other method in all but two vessels (98%). Although most vessels were seen well on one view only on DSA, agreement with sonography was exact in 73% of compared vessels and acceptable in 96%. Furthermore, no difference was found in the rate of agreement with sonography for vessels seen well by DSA on two or more views compared with those seen well on one view only. It was concluded that DSA and sonography are comparable screening methods for carotid disease and that a suboptimal study by either can usually be compensated for by performance of the other.

Magnetic resonance imaging in planning limb-salvage surgery for primary malignant tumors of bone.

In defining the linear extent of a malignant tumor in a long bone, radiographs, computerized tomography, and scintigraphy are routinely employed, especially when non-ablative surgery is being considered. The drawbacks of these modalities in defining the true intracompartmental extent of disease within a bone can largely be overcome with the use of magnetic resonance imaging. We did a prospective analysis of magnetic resonance imaging in sixteen consecutive patients with a primary malignant tumor of a long bone, and it showed that this modality has clinical promise of being more precise than the other modalities in defining the true proximal and distal extent of a tumor in a long bone. Coronal images permit easier planning of surgical techniques for salvage of a limb using an allograft than do a multiplicity of transverse images.

A fast 3D-imaging technique for performing dynamic Gd-enhanced MRI of breast lesions.

The characterization of breast lesions by their Gd-enhancement profiles has been proposed as a method for differentiating benign from malignant breast lesions. The limitations of dynamic contrast enhanced 2D imaging of the breast are the low number of slices that can be acquired, and the need to know the location of the lesion a priori to correctly select the noncontiguous 2D slice locations. These problems are exacerbated when multi-focal disease is present but not anticipated. Standard fast 3D gradient-echo imaging has a variable delay between successive acquisitions. We have developed a fast 3D gradient-echo imaging technique for dynamic Gd-DTPA enhanced breast imaging which obtains multiple 3D image sets of 32 contiguous images at 44 s intervals without an interscan delay time. This rapid 3D imaging technique achieves good temporal resolution and reduces patient motion between pre- and postcontrast images while covering a much larger portion of the breast and eliminating the need for a priori knowledge concerning the location of the lesion(s) when performing Gd-enhanced dynamic MR imaging.

Dynamic sequential 3D gadolinium-enhanced MRI of the whole breast.

Dynamic contrast-enhanced 2D MR imaging of the breast has shown high sensitivity and specificity for the detection and characterization of breast lesions. We investigated the ability of a dynamic fast 3D MR imaging technique that repeatedly scans the whole breast in 44-s intervals without an interscan delay time to obtain similar sensitivity and specificity as 2D imaging. Fifty-six patients scheduled for breast biopsy were entered into the study, and 83 lesions detected by 3D dynamic scanning were biopsied. Dynamic 3D contrast-enhanced breast imaging with subtraction detected and correctly classified all 23 cancers, and 44 of the 60 benign lesions yielding a sensitivity of 100%, a specificity of 73%, and a 100% predictive negative value. The enhancement profiles of metastatic lymph nodes were similar to those of primary cancer. This technique allowed detection of multifocal and multicentric lesions and did not require a prior knowledge of lesion location. These results indicate that dynamic contrast-enhanced 3D MRI of the whole breast is a useful and economically feasible method for staging breast cancer, providing a comprehensive noninvasive method for total evaluation of the breast and axilla in patients considering breast conservation surgery or lumpectomy.

Observer reliability in CT and MRI of the abdomen/pelvis.

The purpose of this research was to evaluate two sources of error in the performance of computerized tomography (CT) and magnetic resonance imaging (MRI) of the abdomen/pelvis. The sources of error assessed were inter- and intra-observer reliability. Thirty abdomen/pelvis CT scans were randomly selected from each of three hospitals (university, VA, military) with different CT scanners. Two radiologists were recruited from each site to be CT observers. Forty-five abdomen/pelvis MRI scans were randomly selected from two institutions with different MRI scanners. Four observers were recruited to read the MRI scans. All scans were read blind without clinical information or patient identification. Overall inter-observer and intra-observer diagnostic agreement was significantly higher for MRI compared to CT. Inter-observer diagnostic agreement rates were also significantly higher for MRI when the etiologies of neoplastic vascular and metabolic/toxic were assigned. Observer experience in CT (range: 5-9 yr) or MRI (range: 2-4 yr) was not statistically associated with improved diagnostic agreement. This research addresses many of the criticisms of the MRI literature and compares MRI favorably to CT.

Correlation of fine needle aspiration biopsy and dynamic contrast-enhanced 3D magnetic resonance imaging of the breast.

OBJECTIVE: To correlate and assess the utility of dynamic contrast-enhanced three-dimensional gadolinium-enhanced magnetic resonance imaging (Gd-3DMRI) and fine needle aspiration biopsy (FNAB) findings in patients with suspected breast disease. STUDY DESIGN: Beginning in 1993, all patients who underwent percutaneous FNAB of the breast and had concurrent Gd-3DMRI evaluation of the breast were selected for this study. Findings for FNAB and Gd-3DMRI were stratified into two categories, positive and negative. Subsequent clinical management decisions, which included surgical intervention and/or clinical follow-up, were recorded for all patients. RESULTS: There were 69 FNABs in 59 patients with corresponding Gd-3DMRI evaluation. A positive result by both FNAB and Gd-3DMRI was found in 15 of 18 malignant cases. FNAB missed one case, and Gd-3DMRI missed two, and each of these was thought to be technical. Combining the methods yielded 100% sensitivity. False positive results on Gd-3DMRI (17 cases) were all confirmed to be benign by FNAB and subsequent tissue evaluation. All 32 cases with combined negative results by FNAB and Gd-3DMRI demonstrated a benign process, yielding a specificity of 100% (32/32). CONCLUSION: Our combined testing modalities showed a high degree of specificity and good sensitivity. FNAB used with dynamic contrast-enhanced Gd-3DMRI can contribute valuable information for physicians treating patients with suspected breast abnormalities.

A magnetic resonance imaging study of horizontal rectus muscle palsies.

The assessment of extraocular muscle function is usually performed indirectly by an examination of ocular motility. We have utilized magnetic resonance imaging, in both cine and static modes, to directly observe the contractility behavior of the extraocular muscles. This noninvasive technique was applied to the study of patients with horizontal rectus muscle palsies. In all cases, the palsied muscle was of a smaller diameter than its normal counterpart. This size differential was noted in all fields of gaze. Additional studies are required to determine the relative contributions of denervation atrophy and loss of tonus to this diminution of muscle size.

Effects of facial paralysis after acoustic neuroma surgery in Norway.

This survey investigated how individuals with facial paralysis resulting from acoustic neuroma surgery manage self-care needs of daily living. Facial paralysis was defined to include damage from surgery to other cranial nerves located in the same area as the facial nerve. The 40 patients surveyed had surgery performed at the Neurosurgical Department, National Hospital of Norway, Oslo, during a four-year period. The instrument used was a questionnaire based on Orem's universal self-care requisites. Results showed that problems related to eating and drinking and certain physiological problems were accepted over time, while pain, eye problems, and hearing loss remained difficult for patients to cope with. Social and psychological problems related to the facial paralysis were ongoing for many patients and seemed to be mitigated by self-acceptance and acceptance by others.

Ipsilateral decubitus position for percutaneous CT-guided adrenal biopsy.

Positioning the patient on the side to be biopsied elevates and relatively immobilizes the diaphragmatic leaf on the dependent side, allowing percutaneous adrenal needle biopsy by a direct posterior approach without traversing lung tissue. The ipsilateral decubitus position was used successfully for biopsy of four small adrenal lesions in which lung precluded a direct posterior approach in the prone position. In addition, the relative stability of the diaphragmatic leaf further facilitated accurate needle placement.

Half-Fourier, three-dimensional technique for dynamic contrast-enhanced MR imaging of both breasts and axillae: initial characterization of breast lesions.

PURPOSE: To evaluate the ability of asymmetric half-Fourier three-dimensional (3D) magnetic resonance (MR) imaging to characterize signal intensity changes in breasts and axillae after contrast material injection and to compare the spatial resolution and measured signal intensity change of asymmetric and symmetric (keyhole) partial Fourier techniques. MATERIALS AND METHODS: Imaging was performed in 28 adult patients by collecting a single full-Fourier 3D data set with bolus injection of contrast material during the last 10 seconds followed by collection of six half-Fourier 3D data sets without interimage delays. Postcontrast keyhole and half-Fourier images were formed from the same full-Fourier raw data set. RESULTS: The asymmetric half-Fourier 3D technique maintained the spatial resolution and lesion signal intensity of the full-Fourier image, whereas the 50% keyhole method degraded the spatial resolution by a factor of two and decreased the lesion signal intensity by 19% for a 2 x 2-pixel region of interest. Histopathologic correlation was attained in 32 lesions in 28 patients. Sensitivity was 100% (five of five) and specificity was 89% (24 of 27). CONCLUSION: The asymmetric half-Fourier 3D MR imaging technique allows imaging of both breasts and axillae without loss of lesion contrast or temporal resolution and provides the maximum spatial resolution and lesion signal intensity attainable for the views sampled.

CT diagnosis of venous pseudotumors in the chest and abdomen.

Appearances simulating neoplastic masses were found in five patients undergoing computed tomographic (CT) scanning of the chest and abdomen for a variety of indications. In each case the appearance was shown to be due to dilated collateral venous channels in association with portal hypertension or interruption of the inferior vena cava. The vascular origin of the masses was confirmed by CT scanning during intravenous bolus injection of contrast. Angiographic confirmation was obtained in three subjects. Enlarged collateral veins should be considered in the differential diagnosis of appearances suggesting mediastinal or abdominal lymphadenopathy at CT scanning.

Effects of varying potential and electrolytic dosage in direct current treatment of tumors.

The effects of different voltages and dosages during direct current treatment were studied to determine the most effective tumor treatment. Groups of nude mice with subcutaneous human colon cancer nodules were treated with a single electrolytic dose (charge) of direct current using two percutaneously placed needle electrodes. All the treated groups responded and the residual tumor volumes were significantly lower (p less than 0.001) than the control group. 7.5 V gave the greatest tumor reduction, significantly more than for 12.5, 10.0, and 2.5 V. 35 C/ml of tumor was more effective than 30 C/ml (p less than 0.05) and no difference in response was obtained between 35 and 50 C/ml. Hyperthermia did not appear to play a significant part in direct current treatment in the examined voltage range as no intra-tumoral temperature elevation was observed. Direct current may allow effective percutaneous treatment of metastases which are unresponsive or unsuitable for conventional treatment.

Normal thymus: CT characteristics in subjects under age 20.

The chest computed tomographic (CT) scans of 40 subjects aged 20 or younger were analyzed retrospectively with special attention to the anterior mediastinum and the thymus. Thirty-four of the patients were considered to have normal CT appearances of the anterior mediastinum; neoplasm was suspected at this site in the other six. In the normal group, the gland was consistently identified as a characteristic anterior mediastinal structure. It had smooth, undulating, lateral contours tending to be convex laterally in the very young and concave laterally at an older age, although there was overlap in many in whom the shape of the lateral contours was a combination of convex, concave, or straight. A sharp angular contour to the lateral margin of the thymus was seen occasionally and is also thought to be characteristic of normal thymus. The posterior border of the gland molded to the heart and great vessels in all patients. The anterior contour was molded to the anterior chest wall or had a pointed shape directed toward the sternum. Molding to the mediastinum and chest wall was not found or was present to only a limited degree in the patients with anterior mediastinal tumor. Attenuation values varied between different normal glands and within the same gland on both pre- and postcontrast scans. Recognition of normal variation in the CT appearance of the thymus in young patients may prevent false-positive diagnosis of neoplasm.