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PubMed2000

Magnetic resonance imaging and magnetic resonance angiography before postchemotherapy retroperitoneal lymph node dissection.

OBJECTIVES: Retroperitoneal lymph node dissection (RPLND) after primary chemotherapy is an accepted therapeutic approach for metastatic nonseminomatous germ cell testicular cancer. Because of the intense desmoplastic reaction and adherence to venous and arterial walls, accurate imaging of the retroperitoneal vasculature and its relation to residual tumor is essential. We report our experience with magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA), including the recently developed technique of bolus-contrast MRA, in patients undergoing postchemotherapy RPLND. METHODS: Eighteen patients underwent MRI of the retroperitoneal region before RPLND. In addition to routine sequences, MRA was performed in 10 patients, including 8 with a three-dimensional technique using bolus intravenous MR contrast. Results were compared with intraoperative and pathologic findings. RESULTS: MRI and MRA provided detailed information on retroperitoneal vasculature and its relation to tumor, including multiple renal vessels (n = 5), duplex inferior vena cava (n = 1), left retroaortic renal vein (n = 2), and common iliac vein thrombus (n = 1). In all cases, bolus-contrast MRA provided unique information on the location and number of renal and lumbar arteries, in addition to information on the aorta and the mesenteric and iliac vessels. The origin and number of renal arteries were accurately identified in all patients by bolus-contrast MRA; 2 patients had supernumerary renal arteries discovered at RPLND that had not been identified on non-bolus-contrast MRI. CONCLUSIONS: Bolus-contrast three-dimensional MRA provides unique information on renal and lumbar vessels. The potential benefit of avoiding vascular injury during dissection should be prospectively evaluated.

Adult↗
PubMed1989

Magnetic resonance imaging versus computed tomography of leukocoric eyes and use of in vitro proton magnetic resonance spectroscopy of retinoblastoma.

To evaluate the usefulness of magnetic resonance imaging (MRI) in the evaluation of leukocoric eyes, the authors studied 28 patients with either leukocoria or intraocular mass with a 1.5-tesla (T) MRI imager. Retinoblastomas were reliably distinguished from Coats' disease, toxocariasis, and persistent hyperplastic primary vitreous on the basis of MRI findings. Calcification cannot be reliably detected on MRI scans. Lesions elevated less than 4 mm may not be detected reliably by MRI at this time. Computed tomography (CT) can detect calcification with a high degree of accuracy. Retinoblastomas appeared as moderately hyperintense masses on T1- and proton-weighted MRIs. They became hypointense in T2-weighted MRIs. This MRI characteristic is similar to that of uveal melanoma. Intraocular calcification in children especially younger than 3 years of age is highly suggestive of retinoblastoma. In the diagnosis of retinoblastoma, MRI is not as specific as CT because of its lack of sensitivity in detecting calcification. However, MRI, because of its superior contrast resolution, offers more information in the differentiation of pathologic intraocular conditions responsible for leukocoria. The authors also describe their preliminary work of in vitro proton magnetic resonance spectroscopy of eyes with retinoblastoma and an eye with uveal melanoma in an 18-year-old black woman.

Adolescent↗
PubMed2000

Neuroprotective effect of lamotrigine and MK-801 on rat brain lesions induced by 3-nitropropionic acid: evaluation by magnetic resonance imaging and in vivo proton magnetic resonance spectroscopy.

Magnetic resonance imaging and in vivo proton magnetic resonance spectroscopy were used to evaluate the therapeutic effect of lamotrigine and MK-801 on rat brain lesions induced by 3-nitropropionic acid. Systemic administration of 3-nitropropionic acid (15 mg/kg per day) to two-month-old Sprague-Dawley rats (n = 10 for each group) for five consecutive days induced selective striatal and hippocampal lesions and specific behavioral change. Pretreatment with lamotrigine (10 mg/kg or 20 mg/kg per day) or MK-801 (2 mg/kg per day) attenuated the lesions and behavioral change. There were no significant differences in T2 values of the striatum and hippocampus among rats pretreated with MK-801, lamotrigine (20 mg/kg) and sham controls. Significant elevations of succinate/creatine and lactate/creatine ratios and decreases of N-acetylaspartate/creatine and choline/creatine ratios were observed after 3-nitropropionic acid injections (P < 0.001). The changes were nearly prevented after pretreatment with lamotrigine (20 mg/kg). However, the N-acetylaspartate/creatine in rats pretreated with lamotrigine (10 mg/kg) (P < 0.01) and MK-801 (P < 0.05) still showed significant reduction as compared with sham controls. Thus we conclude that both lamotrigine and MK-801 are effective in attenuation of brain lesions induced by 3-nitropropionic acid. A higher dose of lamotrigine provides a better neuroprotective effect than MK-801. With a better therapeutic effect and fewer side effects, lamotrigine is more promising for potential clinical application.

Animals↗
PubMed1997

1H magnetic resonance imaging and 31P magnetic resonance spectroscopy in experimental filariasis.

1H Magnetic resonance imaging and 31P magnetic resonance spectroscopy (MRS) have been carried out in experimental rodent filariasis, i.e., Acanthocheilonema viteae infection in the rodent host, Mastomys coucha. The T2-weighted image of the infected host shows fine hyperintense thread like structures of adult filariid nests in the cervical region. 31P MRS of normal and infected hosts, localized over the same region of interest, show seven major peaks corresponding to phosphomonoesters (including glucose-6-phosphate, fructose-6-phosphate, fructose-1-6-diphosphate, phosphorylcholine, and adenine monophosphate or AMP), inorganic phosphate, glycerophosphorylcholine, phosphoenolpyruvate, phosphocreatine and nucleoside di- and tri-phosphates. Concentrations of phosphomonoesters (PMEs) are higher in the normal rodent compared with the infected ones. In vivo 31P MRS provides a non-invasive assessment of tissue bioenergetics and phospholipid metabolism.

Animals↗
PubMed1997

1H and 19F magnetic resonance imaging of solid paramagnetic compounds using large magnetic field gradients and Hahn echoes.

1H and 19F spatially resolved echo trains of a number of paramagnetic solids with apparent magnetic moments as high as 10 Bohr magnetons have been successfully obtained in the 58 T m-1 fringe-field gradient of a 9.4 T superconducting magnet by the use of Hahn echoes. Complexes studied include hydrates of Ni(II), Fe(III), Mn(II), and the anhydrous fluorides of Ti(III), Co(II) and Mn(II). Tris 6,6-7,7-8,8,8 heptafluoro-2,2-dimethyl-3,5octane dionato complexes of several lanthanides, Eu, Dy, Ho and Yb, have also been imaged. Additionally, 1H relaxation time measurements have been obtained at 28 MHz with conventional techniques, and several additional T2 values have been obtained in the stray field for both 1H and 19F.

Calibration↗
PubMed2003

Motor representation in patients rapidly recovering after stroke: a functional magnetic resonance imaging and transcranial magnetic stimulation study.

OBJECTIVE: Neuroimaging studies have suggested an evolution of the brain activation pattern in the course of motor recovery after stroke. Initially poor motor performance is correlated with an recruitment of the uninjured hemisphere that continuously vanished until a nearly normal (contralateral) activation pattern is achieved and motor performance is good. Here we were interested in the early brain activation pattern in patients who showed a good and rapid recovery after stroke. METHODS: Ten patients with first-ever ischemic stroke affecting motor areas had to perform self-paced simple or more complex movements with the affected or the unaffected hand during functional magnetic resonance imaging (fMRI). The location and number of activated voxels above threshold were determined. To study possible changes in the cortical motor output map the amplitude of the motor evoked potentials (MEP) and the extent of the excitable area were determined using transcranial magnetic stimulation (TMS). RESULTS: The pattern of activation observed with movements of the affected and the unaffected hand was similar. In the simple motor task significant (P<0.05) increases were found in the primary motor cortex ipsilateral to the movement, the supplementary motor area and the cerebellar hemisphere contralateral to the movement during performance with the affected hand compared to movements with the unaffected hand. When comparing simple with more complex movements performed with either the affected or the unaffected hand, a further tendency to increased activation in motor areas was observed. The amplitude of MEPs obtained from the affected hemisphere was smaller and the extent of cortical output maps was decreased compared to the unaffected hemisphere; but none of the patients showed MEPs at the affected hand when the ipsilateral unaffected motor cortex was stimulated. CONCLUSIONS: Despite a rapid and nearly complete motor recovery the brain activation pattern was associated with increased activity in (bilateral) motor areas as revealed with fMRI. TMS revealed impaired motor output properties, but failed to demonstrate ipsilateral motor pathways. Successful recovery in our patients may therefore rely on the increased bilateral activation of existing motor networks spared by the injury.

Adult↗
PubMed2003

Plasticity of the human motor system following muscle reconstruction: a magnetic stimulation and functional magnetic resonance imaging study.

OBJECTIVE: Although motor system plasticity in response to neuromuscular injury has been documented, few studies have examined recovered and functioning muscles in the human. We examined brain changes in a group of patients who had a muscle transfer. METHODS: Transcranial magnetic stimulation (TMS) was used to study a unique group of 9 patients who had upper extremity motor function restored using microneurovascular transfer of the gracilis muscle. The findings from the reconstructed muscle were compared to the homologous muscle of the intact arm. One patient was also studied with functional magnetic resonance imaging (fMRI). RESULTS: TMS showed that the motor threshold and short interval intracortical inhibition was reduced on the transplanted side while at rest but not during muscle activation. The difference in motor threshold decreased with the time since surgery. TMS mapping showed no significant difference in the location and size of the representation of the reconstructed muscle in the motor cortex compared to the intact side. In one patient with reconstructed biceps muscle innervated by the intercostal nerves, both TMS mapping and fMRI showed that the upper limb area rather than the trunk area of the motor cortex controlled the reconstructed muscle. CONCLUSIONS: Plasticity occurs in cortical areas projecting to functionally relevant muscles. Changes in the neuronal level are not necessarily accompanied by changes in motor representation. Brain reorganization may involve multiple processes mediated by different mechanisms and continues to evolve long after the initial injury. SIGNIFICANCE: Central nervous system plasticity following neuromuscular injury may have functional relevance.

Adolescent↗
PubMed1998

31P-magnetic resonance spectroscopy and 2H-magnetic resonance imaging studies of a panel of early-generation transplanted murine tumour models.

The objective of this study was first to determine whether three slowly growing early-generation murine transplantable tumours, the T40 fibrosarcoma, T115 mammary carcinoma and T237 lung carcinoma, exhibit patterns of energetics and blood flow during growth that are different from those of the faster growing RIF-1 fibrosarcoma. Serial measurements were made with 31P-magnetic resonance spectroscopy (MRS), relating to nutritive blood flow and 2H-magnetic resonance imaging (MRI), which is sensitive to both nutritive and large-vessel (non-nutritive) flow. All four tumour lines showed a decrease in betaNTP/Pi and pH with growth; however, each line showed a different pattern of blood flow that did not correlate with the decrease in energetics. Qualitative histological analysis strongly correlated with the 2H-MRI. Second, their response to 5 mg kg(-1) hydralazine i.v. was monitored by 31P-MRS. A marked decrease in betaNTP/Pi and pH was observed in both the RIF-1 fibrosarcoma and the third-generation T115 mammary carcinoma after hydralazine challenge. In contrast, the fourth generation T40 fibrosarcoma and T237 lung carcinoma showed no change in 31P-MRS parameters. However, a fifth-generation T237 cohort, which grew approximately three times faster than fourth-generation T237 cohorts, exhibited a significant deterioration in betaNTP/Pi and pH in response to hydralazine. These data are consistent with a decoupling between large-vessel and nutritive blood flow and indicate that early-generation transplants that have a slow growth rate and vascular tone are more appropriate models of human tumour vasculature than more rapidly growing, repeatedly transplanted tumours.

Animals↗
PubMed2005

Magnetic resonance imaging and magnetic resonance spectroscopic imaging of prostate cancer.

Magnetic resonance imaging (MRI) and magnetic resonance spectroscopic imaging (MRSI) are evolving techniques that offer noninvasive evaluation of anatomic and metabolic features of prostate cancer. The ability of MRI to determine the location and extent of the tumor and to identify metastatic spread is useful in the pretreatment setting, enabling treatment decision-making that is evidence-based. MRSI of the prostate gland expands the diagnostic assessment of prostate cancer through the detection of cellular metabolites, and can lead to noninvasive differentiation of cancer from healthy tissue. MRI/MRSI can also be used to evaluate both local and systemic recurrence, with endorectal MRI being capable of detecting local recurrence, even in patients with rising serum PSA level but no palpable tumor on digital rectal examination. Considering the benefits that MRI and MRSI have been shown to offer patients, the skills and technology required to perform these tests should be widely disseminated to make their routine use possible. Teamwork between members of radiology, pathology, urology and radiation oncology departments is essential in order to exploit these technologies fully.

Humans↗
PubMed2001

Combined functional magnetic resonance imaging and transcranial magnetic stimulation evidence of ipsilateral motor pathway with congenital brain disorder: a case report.

We present the case of 28-year-old man with schizencephaly who had mild left hemiparesis with mirror movement. Brain mapping using functional magnetic resonance imaging (fMRI) and transcranial magnetic stimulation (TMS) for both hand muscles was done to evaluate his neurologic state. Motor evoked potential (MEP) from both abductor pollicis brevis (APB) muscles was obtained simultaneously. fMRI showed that the left primary sensorimotor cortex became active when the right fingers performed the flexion-extension exercise. The left primary sensorimotor cortex, left prefrontal area, and both supplementary motor areas were activated with flexion-extension exercise of the left hand. Brain mapping for both APB muscles using TMS showed that no MEP was evoked in the right hemisphere, but a APB total of 5 sites were evoked in the left hemisphere simultaneously. The optimal scalp site for both APB muscles was present at the same site. The MEPs of both muscles which were evoked by stimulation of the optimal scalp site, showed similar latencies, amplitudes, and figures of potential. The similarities in both MEPs and the same optimal scalp site support the assumption that MEPs of both APB muscles are produced by the corticospinal tract originating from the same motor cortex. Our results showed that the ipsilateral motor pathway extended from the unaffected left hemisphere to both hand muscles. This finding may reflect functional reorganization of motor area in a patient with congenital brain disorder.

Adult↗
PubMed1993

Diffuse white matter disease in three children: an encephalopathy with unique features on magnetic resonance imaging and proton magnetic resonance spectroscopy.

Amongst 21 children with unclassified white matter diseases three patients could be characterised by an identical clinical picture, magnetic resonance imaging (MRI) and proton magnetic resonance spectroscopy (MRS) findings as a probably distinct entity. Following a normal early development they later showed rapidly progressive motor symptoms (ataxia, spasticity) leading to severe handicap within one or two years after onset. Later on bulbar symptoms, optic atrophy and epileptic seizures occurred. The MRI showed a diffuse homogeneous hypodensity of the white matter almost identical to the signal of the ventricles. MRS revealed a near total absence of N-acetylaspartate, choline and creatine and an increase of lactate and glucose. One girl and one boy were siblings, indicating an autosomal recessive trait.

Aspartic Acid↗
PubMed2005

Magnetic resonance imaging including magnetic resonance cholangiopancreatography for tumor localization and therapy planning in malignant hilar obstructions.

PURPOSE: To assess image quality and overall accuracy of magnetic resonance imaging (MRI), including two magnetic cholangiopancreatography (MRCP) techniques, for the diagnostics and preoperative work-up of malignant hilar obstructions. MATERIAL AND METHODS: Thirty-one patients with malignant hilar obstructions (hilar cholangiocarcinoma, n=30; hepatocellular carcinoma, n=1) received MRCP by two techniques (single-shot thick-slab and multisection thin-slice MRCP) and unenhanced and contrast material-enhanced MRI. MR assessment included the evaluation of image quality and visualization of bile ducts (5-point scale), and the classification of tumor status. MR results were subsequently correlated with the results from surgery and pathology. RESULTS: The maximum intensity projections of multisection thin-slice MRCP had significantly more artifacts compared to MRCP in the single-shot thick-slab technique, and overall image quality of single-shot thick-slab MRCP was rated significantly superior compared to multisection thin-slice MRCP (4.4 +/- 0.7 and 4.1 +/- 0.9, respectively). Moreover, ductal visualization of different parts of the biliary system was rated superior with single-shot thick-slab MRCP. In contrast, the original data from multisection thin slice MRCP facilitated visualization of periductal lesions and adjacent structures. Overall MR accuracy for the assessment of tumor status, periductal infiltration, and lymph node metastases was 90%, 87%, and 66%, respectively. CONCLUSION: For evaluation of malignant hilar obstructions, MRCP by the single-shot thick-slab technique had superior image quality and fewer artifacts; in contrast, besides sole biliary visualization, multisection MRCP depicted complementary adjacent parenchymal and periductal structures. We therefore recommend MRI, with a combination of both MRCP techniques, for the diagnostic work-up and therapy planning of malignant hilar obstructions.

Adult↗
PubMed2007

Comparison of gadolinium-enhanced cardiovascular magnetic resonance angiography with high-resolution black blood cardiovascular magnetic resonance for assessing carotid artery stenosis.

PURPOSE: Carotid angiography is used to assess stroke risk, but it cannot reliably characterize plaque burden because the vessel remodels during plaque formation. High-resolution black blood cardiovascular magnetic resonance (BBCMR) depicts the outer wall thereby providing a truer estimate of plaque size. We compared carotid stenosis by gadolinium enhancement cardiovascular magnetic resonance angiography (CMRA) versus high-resolution BBCMR. METHODS: Twenty-four subjects (M:F = 20:4; ages 57-83 years) with carotid atherosclerosis underwent CMRA and transaxial BBCMR through the stenosis. Area and diameter stenosis measurements by NASCET criteria using CMRA images were compared to area stenosis measurements based on outer wall and lumen contours drawn on corresponding BBCMR images. RESULTS: Area stenosis by CMRA correlated with area stenosis by BBCMR (r = 0.77; 95% CI: 0.58, 0.89). BBCMR values exceeded corresponding CMRA area measurements in 20 of 24 cases, with the remainder being highly stenotic (> 90%). CONCLUSION: CMRA yields lower estimates of luminal narrowing compared to BBCMR, which delineates the outer wall and accounts for vascular remodeling. BBCMR could serve as a new measure of narrowing to guide management, but prospective studies are needed to better understand the clinical implications of this new scale of disease.

Aged↗
PubMedDate not supplied

Demineralized bone matrix-induced ectopic bone formation in rats: in vivo study with follow-up by magnetic resonance imaging, magnetic resonance angiography, and dual-energy X-ray absorptiometry.

The aim of this study was to further explore the use of magnetic resonance imaging (MRI), magnetic resonance angiography (MRA), and dual-energy X-ray absorptiometry (DEXA) to assess bone formation and blood circulation in a pedicled bone graft substitute. In 14 Wistar rats, initially 10 weeks old, heterogeneous demineralized femur bone matrix implants were wrapped in pedicled adductor thigh muscle flaps. One rat died after surgery. Subsequently, bone formation and maintenance of blood vessel functionality were evaluated in six rats 6 weeks postimplantation by means of in vivo MRI/MRA and postmortem histomorphometry. The other seven rats were left for 12 weeks, whereafter bone formation was evaluated by in vivo DEXA and postmortem histomorphometry. The results demonstrated that after 6 weeks bone formation was present in four of six animals, quantified as 42 (+/-35)% and 25 (+/-19)% by means of MRI and histomorphometry, respectively. MRA was able to show patency of the pedicles of these four rats only, which suggests that the lack of blood supply in the other two rats is the cause of the failure to form bone. In the 12-week group, histology showed increased bone formation without signs of osteolysis, which was quantified histomorphometrically to be as high as 48 (+/-15)%. DEXA failed to show bone formation. It is concluded that in vivo MRI proved to be a reliable method for monitoring ectopic bone formation in a rat model, whereas in vivo DEXA was unable to detect the implants. Furthermore, in vivo MRA proved to be a useful technique for studying the circulation of muscle flaps in this animal model.

Absorptiometry, Photon↗
PubMed1990

Magnetic starch microspheres, efficacy and elimination. A new organ-specific contrast agent for magnetic resonance imaging.

A new particulate magnetic resonance (MR) contrast agent was prepared by controlled precipitation of iron oxide in an aqueous starch solution. The potential of the magnetic starch microspheres (MSM) as a hepatosplenic contrast enhancer was studied by MR spectroscopy and MR imaging. Intravascular administration of MSM to rodents showed an effective blood clearance and a tissue-specific localization of the substance. MSM doses in a range of 0.3-1.5 mg Fe/kg caused a 50% alteration in sensitive contrast parameters (ED50 doses) of liver and spleen. The contrast effect of MSM in liver and spleen was halved within 2 to 5 days. The approximated lethal MSM dose in mice was 150-200 mg Fe/kg. MSM is a tissue-specific MR contrast substance with high efficacy, rapid bioelimination, and low acute toxicity.

Animals↗
PubMed2002

Quantitative T(1rho) and magnetization transfer magnetic resonance imaging of acute cerebral ischemia in the rat.

It has been previously shown that T1 in the rotating frame (T(1rho)) is a very sensitive and early marker of cerebral ischemia and that, interestingly, it can provide prognostic information about the degree of subsequent neuronal damage. In the present study the authors have quantified T(1rho) together with the rate and other variables of magnetization transfer (MT) associated with spin interactions between the bulk and semisolid macromolecular pools by means of Z spectroscopy, to examine the possible overlap of mechanisms affecting these magnetic resonance imaging contrasts. Substantial prolongation of cerebral T(1rho) was observed minutes after induction of ischemia, this change progressing in a time-dependent manner. Difference Z spectra (contralateral nonischemic minus ischemic brain tissue) showed a significant positive reminder in the time points from 0.5 to 3 hours after induction of ischemia, the polarity of this change reversing by 24 hours. Detailed analysis of the MT variables showed that the initial Z spectral changes were due to concerted increase in the maximal MT (+3%) and amount of MT (+4%). Interestingly, the MT rates derived either from the entire frequency range of Z spectra or the time constant for the first-order forward exchange (k(sat)) were unchanged at this time, these variables reducing only one day after induction of ischemia. The authors conclude that T(1rho) changes in the acute phase of ischemia coincide with both elevated maximal MT and amount of MT. These changes occur independent of the overall MT rate and in the absence of net water gain to the tissue, whereas in the consolidating infarction the decrease in the rate and amount of MT, as well as the extensive prolongation of T(1rho), are associated with water accumulation.

Animals↗
PubMed2000

Lack of significant changes on magnetic resonance scans before and after 2 weeks of daily left prefrontal repetitive transcranial magnetic stimulation for depression.

Repetitive transcranial magnetic stimulation (rTMS) is a new technology for exploring brain function. With this method, a small electromagnet is placed on the scalp; by activating and deactivating it, nerve cells in the underlying superficial cortex are depolarized. Several studies have found that prefrontal rTMS has potential efficacy in treating depression, and this technology, in addition to being a research tool, may soon play a role in psychiatric practice. Thus, establishing the safety of this technology is important and has been studied insufficiently. The authors performed T1-weighted three-dimensional volumetric magnetic resonance (MR) imaging on 22 depressed adults (15 active, 7 control) before and after they participated in a 2-week double-blinded, placebo-controlled trial of daily left prefrontal rTMS for the treatment of depression (a total of 16,000 stimuli). Seventeen patients also had paired T2-weighted scans. In a blinded manner, MR scans were qualitatively and quantitatively assessed for structural changes. No qualitative structural differences were observed before and after treatment. In addition, volumetric analysis of the prefrontal lobe showed no changes in the 2 weeks of the study. In conclusion, 10 days of daily prefrontal rTMS at these intensities and frequencies does not cause observable structural changes on MR scans in depressed adults.

Adult↗
PubMed1999

Interactive 3-D registration of ultrasound and magnetic resonance images based on a magnetic position sensor.

The use of stereotactic systems has been one of the main approaches for image-based guidance of the surgical tool within the brain. The main limitation of stereotactic systems is that they are based on preoperative images that might become outdated and invalid during the course of surgery. Ultrasound (US) is considered the most practical and cost-effective intraoperative imaging modality, but US images inherently have a low signal-to-noise ratio. Integrating intraoperative US with stereotactic systems has recently been attempted. In this paper, we present a new system for interactively registering two-dimensional US and three-dimensional magnetic resonance (MR) images. This registration is based on tracking the US probe with a dc magnetic position sensor. We have performed an extensive analysis of the errors of our system by using a custom-built phantom. The registration error between the MR and the position sensor space was found to have a mean value of 1.78 mm and a standard deviation of 0.18 mm. The registration error between US and MR space was dependent on the distance of the target point from the US probe face. For a 3.5-MHz phased one-dimensional array transducer and a depth of 6 cm, the mean value of the registration error was 2.00 mm and the standard deviation was 0.75 mm. The registered MR images were reconstructed using either zeroth-order or first-order interpolation. The ease of use and the interactive nature of our system (approximately 6.5 frames/s for 344 x 310 images and first-order interpolation on a Pentium II 450 MHz) demonstrates its potential to be used in the operating room.

Algorithms↗