Deuterium MR in Vivo Imaging of the Rat Eye Using 2H2O

In vivo euterium MR imaging (2H MR) was investigated in rats after intraperitoneal administration of deuterated saline, and a dynamic study of the water movement in rat eyes was performed. Deuterium MR imaging was carried out by means of a gradient-echo (GRE) and a spin-echo (SE) pulse sequence. The rat eye was imaged in 2H MR more selectively by SE than by GRE, but a lower signal-to-noise ratio was obtained in 2H MR imaging using the SE sequence. The MR signal intensity of the rat eye was followed by a 3-compartment model, which enabled determination of the flow rate constant of the water in the eye (0.359/min). Deuterium MR imaging is useful to visualize the dynamic change of water in rat eyes using 2H MR at the same magnetic field (2 T) that can also be used for conventional MR imaging in humans.

Degeneration of patellar cartilage in patients with recurrent patellar dislocation following conservative treatment: evaluation with delayed gadolinium-enhanced magnetic resonance imaging of cartilage

OBJECTIVE

To examine the characteristics of cartilage degeneration in patients with recurrent patellar dislocation (RPD) following conservative treatment using delayed gadolinium-enhanced magnetic resonance imaging (MRI) of cartilage (dGEMRIC).

DESIGN

This study evaluated three groups of knees: group I, 35 knees from both knees of patients with bilateral RPD and dislocated side knees of patients with unilateral RPD; group II, 15 non-dislocated side knees of patients with unilateral RPD; and group III, 20 knees from both knees of healthy volunteers. Differences in post-contrast T1 [T1(Gd)] of cartilage at both medial and lateral facets between groups I, II and III were analyzed. For group I, possible relationships were evaluated between T1(Gd) of cartilage and patient age, length of time between the initial dislocation and MRI and the total number of dislocations between the initial dislocation and MRI for both medial and lateral facets.

RESULTS

The mean T1(Gd) of cartilage at medial facets for groups I, II and III were 411+/-46ms, 465+/-38ms and 490+/-29ms, respectively; there were significant differences between these means (P<0.05). The mean T1(Gd) of cartilage at lateral facets for groups I, II and III were 426+/-53ms, 466+/-45ms and 510+/-36ms, respectively; there were also significant differences between these means (P<0.05). Significant correlations were observed between T1(Gd) of cartilage for both medial and lateral facets and length of time between the initial dislocation and MRI (P<0.05). No other correlations were significant.

CONCLUSION

dGEMRIC may be a useful method to monitor glycosaminoglycan concentration in patients with RPD following conservative treatment.

Visualization of in vivo electroporation-mediated transgene expression in experimental tumors by optical and magnetic resonance imaging

In vivo electroporation (EP) is an efficient method for effective gene transfer and is highly expected for application in anticancer gene therapy. Non-invasive monitoring of gene transfer/expression is critical for optimal gene therapy. Here we report in vivo optical and high-field magnetic resonance imaging (MRI) of EP-mediated transgene expression in a tumor model. Initially, we observed spatio-temporal change in in vivo EP-mediated transgene expression by optical imaging using red fluorescence protein (RFP) as a reporter gene. Next, we constructed a dual-reporter plasmid carrying a gene-encoding MRI reporter ferritin heavy chain and RFP gene to visualize the intratumoral transgene expression by dual modality. Cells transfected with this plasmid showed lower signal intensity on in vitro T(2)-weighted cellular MRI and quantitatively increased the transverse relaxation rate (1/T(2)) compared with control cells. After conducting in vivo EP in an experimental tumor, the plasmid-injected region showed both fluorescent emissions in optical imaging and detectably lowered signal on T(2)-weighted MRI. The correlative immunohistological findings confirmed that both the reporter transgenes were co-expressed in this region. Thus, our strategy provides a platform for evaluating EP-mediated cancer gene therapy easily and safely without administering contrast agent or substrate.

Proton magnetic resonance imaging of flow motion of heavy water injected into a hollow fiber dialyzer filled with saline

Observations using MRI were performed for the motion of heavy water injected into a hollow fiber dialyzer. A cylindrical dialyzer houses a bundle of 10,000 hollow fibers. Because blood components permeate through the hollow fiber membrane from the interior to the exterior of the hollow fiber, which is the dialysate flow path, uniformity of dialysate flow is required. The dialyzer was initially filled with saline and heavy water was injected into the inlet port of the dialysate flow path. MRI tuned for protons could distinguish the injected heavy water from the already present saline. Due to the specific gravity difference, MRI could observe the sedimentation of the injected heavy water flowing beneath the already present saline. The uniformity of the dialysate flow was supported by the finding that the injected heavy water brought about uniform sedimentation and distributed the already present saline uniformly throughout the entire volume of the dialyzer.

Detection of small degree of nonuniformity in dialysate flow in hollow-fiber dialyzer using proton magnetic resonance imaging

A small degree of nonuniformity in dialysate flow in a hollow-fiber dialyzer was detected using proton magnetic resonance imaging (MRI). Since paramagnetic ions reduce the spin-lattice relaxation time of protons around them, MRI can detect Gd in water. An aqueous solution of a chelate compound of Gd was impulsively injected into the dialysate flow path at a flow rate of 500 cm(3) /m, which is that utilized in actual dialysis. Despite the apparent elimination of Gd from the dialysate flow path by the newly injected dialysate fluid after the injection of Gd was terminated, MRI revealed that Gd remained in the interior of the hollow fiber. The observed structure pattern of the Gd concentration profile revealed that the dialysate flow had a small degree of nonuniformity despite the currently established design to restrict channeling in dialysate flow. Local nonuniformity of the hollow-fiber density and vortex generation in the dialysate flow were considered to cause the nonuniformity in the dialysate flow.

Distinctly abnormal brain metabolism in late-onset ornithine transcarbamylase deficiency

OBJECTIVE

To assess alterations in brain metabolites in patients with late-onset ornithine transcarbamylase deficiency (OTCD).

METHODS

Six unrelated, asymptomatic Japanese late-onset OTCD patients were analyzed by proton MRS ((1)HMRS) using a point-resolved spectroscopy technique (repetition and echo times, 5000 and 30 ms). Localized spectra for the centrum semiovale were acquired and absolute metabolite concentrations were calculated using an LCModel.

RESULTS

Compared with age-matched controls, N-acetylaspartate and creatine concentrations were normal in all patients. The glutamine (Gln) plus glutamate concentration was increased in four patients, which progressed in proportion to the clinical stage. myo-inositol (mI) could not be detected in five symptomatic patients. A decreased choline (Cho) concentration was detected in two clinically severe patients. (1)HMRS after liver transplantation in one patient revealed the normalization of all metabolites.

CONCLUSION

These findings suggest progression of neurochemical events in OTCD, i.e., mI depletion and Gln accumulation followed by Cho depletion, which is reverse of that in hepatic encephalopathy, i.e., Cho depletion followed by mI depletion and Gln accumulation.

Brain N-acetylaspartate is elevated in Pelizaeus-Merzbacher disease with PLP1 duplication

OBJECTIVE

To assess alterations in brain metabolites of patients with Pelizaeus-Merzbacher disease (PMD) with the proteolipid protein gene 1 (PLP1) duplications using quantitative proton MRS.

METHODS

Five unrelated male Japanese patients with PMD with PLP1 duplications were analyzed using automated proton brain examination with the point resolved spectroscopy technique (repetition and echo time of 5,000 and 30 msec). Localized spectra in the posterior portion of the centrum semiovale were acquired, and absolute metabolite concentrations were calculated using the LCModel.

RESULTS

Absolute concentrations of N-acetylaspartate (NAA), creatine (Cr), and myoinositol (MI) were increased by 16% (p < 0.01), 43% (p < 0.001), and 31% (p < 0.01) in patients with PMD as compared with age-matched controls. There was no statistical difference in choline concentration.

CONCLUSION

The increased concentration of NAA, which could not be detected by previous relative quantitation methods, suggests two possibilities: axonal involvement secondary to dysmyelination, or increased cell population of oligodendrocyte progenitors. Elevated Cr and MI concentrations may reflect the reactive astrocytic gliosis. Our study thus emphasizes the importance of absolute quantitation of metabolites to investigate the disease mechanism of the dysmyelinating disorders of the CNS.

Long-term assessment of posttransplant renal prognosis with 31 P magnetic resonance spectroscopy

BACKGROUND

31P-magnetic resonance spectroscopy (MRS) has been widely used to study pretransplantation renal viability, and although some had discussed posttransplant renal viability, no one has examined long-term posttransplant renal prognosis. We discuss the use of 31P-MRS to assess the long-term prognosis from the time when MRS was performed.

METHODS

We studied 20 patients with renal allografts. 1.5 Tesla clinical magnetic resonance imaging (MRI) and 15 cm surface coil was used for 31P-MRS. Localized 31P-MRS was done using image selected in vivo spectroscopy (ISIS) method. Individual peaks were fitted by Lorenzian line-shapes with a least square method and peak area ratios were calculated.

RESULTS

A beta-adenosine triphosphate/inorganic phosphate (beta-ATP/Pi) ratio >1.2 had sensitivity of 92.8%, specificity of 100%, and accuracy of 95% for predicting 3-year renal survival; a beta-ATP/Pi ratio >1.2 had sensitivity of 90.9%, specificity of 66.7%, and accuracy of 76.9% for predicting 5-year renal survival. We compared 31P-MRS spectra data between the survived group and failed group. The survived group had significantly higher beta-ATP/Pi, alpha-ATP/Pi, and phosphodiester (PDE)/Pi ratios than the failed group.

CONCLUSIONS

We discussed the beta-ATP/Pi value as a parameter for predicting long-term survival of a transplanted kidney from the time when MRS was performed. A value above 1.2 suggests a high probability of 3-year renal survival, whereas a value over 2.5 indicates that the transplanted kidney could survive over 5 years. 31P-MRS may be useful for predicting long-term survival of transplanted kidneys, but additional studies are needed.

7Li 2D CSI of human brain on a clinical scanner

Lithium salts have been widely used in the treatment of mood disorders, but the mechanism of action is still not clear. In this work, a methodology for two-dimensional Lithium-7 imaging on clinical systems is presented. The data were acquired using a phosphorus volume head coil that was re-tuned for the Lithium-7 frequency. A spectroscopic sequence was used to acquire the free induction decay (FID) after volume excitation using a hard pulse. The results obtained on the head of patients undergoing lithium treatment (n = 7, 0.6 mEq/l average serum level) demonstrate that images of adequate signal to noise ratio (100:1) can be obtained in acceptable imaging times (55 min) using the proposed methodology. The distribution of 7Li appears uniform in the brains of the patients studied.

Seizure frequency and bilateral temporal abnormalities: a proton magnetic resonance spectroscopy of temporal lobe epilepsy

Proton magnetic resonance spectroscopy ((1)H-MRS) was performed in seven healthy volunteers and 17 patients with temporal lobe epilepsy (TLE) to clarify the correlation of the severity of epilepsy with bilateral temporal changes in N-acetylaspartate (NAA), choline-containing compounds (Cho) and creatine + phosphocreatine (Cr). Despite unilateral EEG focus, bilateral temporal reduction in NAA /(Cho + Cr) was revealed in patients with intractable seizures. The potential for seizure generation correlated with the NAA /(Cho + Cr) reduction not only on the ipsilateral side but also on the contralateral side. Proton MRS proved to be a useful measurement for obtaining important information about the neuronal changes as well as the lateralization of the epileptogenic focus in TLE patients.

Hot spots observed on pulmonary perfusion imaging: a case report

A case of hot spots observed on perfusion lung images is presented. This artifact is well known, however, it is rarely seen in our experience. Although this artifact can occur if a faulty injection technique is used, the artifact also may be caused by embolization of the MAA in the upper extremity venous blood after injection. This cause of the artifact is beyond the control of the nuclear medicine professional.

A preliminary study for clinical pharmacokinetics of oral fluorine anticancer medicines using the commercial MRI system 19F-MRS

These preliminary studies of dynamic natural abundance 19F-magnetic resonance spectroscopy (19F-MRS) on 5-FU based medicines were performed in the human liver using commercial 1.5 T MRI equipment. A single tuned, custom-made circular shape surface coil with a diameter of 15 cm operating at 60 MHz was used for the 19F-MRS study. Localized proton shimming with a whole body coil was performed with adequate volume to include the observing area of the surface coil, and the line width of the water signal was less than 40 Hz. Very different spectroscopic appearance patterns of 5-FU were observed. We examined whether the pharmacokinetics in the liver of orally administered 1-hexylcarbamoyl-5-fluorouracil (HCFU) differ from those of orally administered 5'-deoxy-5-fluorouridine (5'-DFUR). This preliminary study suggested the 19F-MRS technique could be a useful method of evaluating in vivo the metabolism of 5-FU based medicines.

Multiple extra-bone accumulations of technetium-99m-HMDP

Bone scintigraphy was performed on a woman 2 y and 10 mo after surgery for rectal cancer. Intense extra-bone accumulations of 99mTc-HMDP were visible in an aortic atherosclerosis lesion and in a metastatic liver tumor. Uptake in the metastatic lesion was confirmed by x-ray CT. Uptake in the aortic lesion was shown as typical calcification by x-ray CT.

Acute pan-costochondritis demonstrated by gallium scintigraphy

Costochondral inflammation is a rare clinical finding. A case is presented, in which acute chostochondritis is demonstrated by gallium scinitigraphy.

Dialysate pressure isobars in a hollow-fiber dialyzer determined from magnetic resonance imaging and numerical simulation of dialysate flow

A procedure to determine dialysate pressure isobars by comparing the results of magnetic resonance imaging (MRI) and numerical simulation of the dialysate flow was established. The assumption used in the filtration analyses, that the dialysate pressure varies only in the central-axial direction, is supported by the finding that the determined isobars have no steep radial gradient. MRI of the contrast solution permeating the hollow fibers verifies the uniformity of the hollow fiber density in the dialyzer.

Occult intestinal bleeding imaged by technetium-99m-HSA-D radionuclide angiography: a case report

Radionuclide angiography (RNA) with 99mTc-diethylenetriamine pentaacetic acid human serum albumin (99mTc-HSA-D) is a sensitive screening method for diagnosing systemic perfusion abnormalities. Sometimes the results produce unexpected information. This information is helpful when considering the clinical perfusion pathophysiology. Recently, we were able to detect an intestinal bleeding lesion clearly for a patient by using RNA.

Human hepatic carbohydrate metabolism. Dynamic observation using 13C MRS without proton decoupling

PURPOSE

Dynamic natural-abundance 13C MR spectroscopy (MRS) studies without proton decoupling were performed in the human liver using commercial 1.5 T MR equipment.

MATERIAL AND METHODS

A single tuned custom-made circular surface coil with an OD of 20 cm operating at 16.04 MHz was used for the 13C study. Seventy-five grams of glucose dissolved in water was administered for the natural-abundance 13C-MRS dynamic study which lasted for approximately 40 to 60 min. Data acquisition was broken into 20-min and 1.7-min blocks. Localized proton shimming with a whole-body coil was performed with sufficient volume to include the observing area of the surface coil; the line width of the water signal was less than 20 Hz.

RESULTS AND CONCLUSION

The glucose and glycogen spectra were clearly visible at 80 to 120 ppm after oral administration of the glucose solution. These data demonstrate that dynamic hepatic carbohydrate metabolism can be observed with commercially available MR equipment. Given that the human hepatic glycogen pool reaches maximum level within less than 10 min, this technique should provide a direct diagnosis of hepatic carbohydrate metabolic disorders.

The measurement of blood flow parameters with deuterium stable isotope MR imaging

METHODS

Because there are no radioactive hydrogen isotopes which can be used for clinical examinations, deuterium as a non-radioactive, freely diffusible tracer has some advantages compared with the radioactive tracers in the measurement of blood flow parameters. A non-invasive technique to estimate the mean tissue blood flow parameter in vivo was developed by using deuterium nuclear magnetic resonance (NMR) imaging in rat. We obtained the NMR signal changes from deuterium NMR images in nine male Wister rats after intravenous injection of D2O and applied exponential curve fitting analyses to calculate blood flow parameters of the brain, heart and skeletal muscle.

RESULTS

While fitting the reducing of the monoexponential function yielded a blood flow parameter of 27.9 +/- 1.6 ml/min/100 g tissue weight for the brain and 46.7 +/- 3.7 ml/min/100 g tissue weight for the heart, fitting the early reducing of the signal intensity of the biexponential function yielded a blood flow parameter of 95.6 +/- 10.9 ml/min/100 g tissue weight for the brain and 108.0 +/- 13.1 ml/min/100 g tissue weight for the heart. The mean muscle blood flow parameter determined by the monoexponential uptake function was 43.8 +/- 7.3 ml/min/100 g tissue weight.

CONCLUSIONS

The blood flow parameter measurement by means of an imaging coil for deuterium is less invasive and reflects the mean tissue blood flow parameter for the entire tissue sample more homogeneously than spectroscopic monitoring.

Assessment of energy status and fructose metabolism of liver in obstructive jaundice by 31P magnetic resonance spectroscopy

The effect of cholestasis on hepatic energy status and fructose metabolism in jaundiced rats and patients was investigated using 31P magnetic resonance spectroscopy. Rats with obstructive jaundice (OJ group) were studied 7 days after bile duct ligation. Drainage rats were studied at 3 days (DR3 group) and 7 days (DR7 group) after the relief of 1 week obstruction of the common bile duct. In the bile duct ligated rat, the beta-adenosine triphosphate (ATP)/Pi (inorganic phosphate) ratio was significantly lower than in sham-operated controls. This ratio recovered rapidly in the DR3 and DR7 groups. The maximum increase in the phosphomonoester peak (PMEmax) after an intravenous bolus of fructose was significantly reduced in both the OJ and DR3 groups, and was accompanied by a decrease in hepatic fructokinase activity. The PMEmax and the fructokinase activity recovered in the DR7 group. In a clinical study, the beta-ATP/Pi ratio in six healthy volunteers was comparable to that of 15 patients with obstructive jaundice, regardless of their biliary drainage status. The PMEmax in all patients (serum bilirubin > or = 5 mg/dL), irrespective of biliary drainage, was significantly lower than in volunteers. Furthermore, the PMEmax in four of the eight patients with biliary drainage (serum bilirubin < 5 mg/dL) was lower than in volunteers. It is concluded that while energy status in jaundiced patients is well maintained, fructose phosphorylation is inhibited and recovery is delayed after the relief of obstruction compared with serum bilirubin. For the non-invasive evaluation of damaged liver function in jaundice, 31P magnetic resonance spectroscopy is a useful technique.

Magnetic resonance imaging of reticulo-endothelial system in patients with idiopathic thrombocytopenic purpura

Idiopathic thrombocytopenic purpura (ITP) is characterized by accelerated platelet destruction in the reticulo-endothelial system (RES). We performed magnetic resonance imaging (MRI) to estimate the degree of activated RES. MRI was performed with a Gyroscan S-15 (1.5 tesla) in 7 healthy volunteers and 22 patients with ITP. The 22 patients included 19 who were at initial diagnosis or were nonresponders to the therapy (non-DX group), and 3 who were responders. For the non-DX group, the T1 relaxation time of the spleen was initially significantly shorter than for healthy volunteers, but normalized after responding to the therapy. The initially shorter T1 values of the spleen for ITP patients correlated with a low platelet count (P < 0.05). This condition may indicate foam cells or fatty components due to platelet destruction. There was no significant relationship between the sequestration in (111)In-scan and T1 values of the liver or spleen. However, MRI is a noninvasive method, and it may be a clinically useful tool in the evaluation of RES in patients with ITP.

[Measurement of cerebral blood flow using phase-contrast MRI]

The development of phase-contrast magnetic resonance imaging(P-C MRI) provides a noninvasive method for measurement of volumetric blood flow(VFR). The VFR of the left and right internal carotid arteries and basilar artery were measured using P-C MRI, and total cerebral blood flow(tCBF) was calculated by summing up the VFR values in three vessels. We investigated the changes in these blood flows as influenced from age, head size, height, weight, body surface area and handedness. Moreover, regional CBF(rCBF) was measured by combining with the single photon emission computed tomography(SPECT) of 123I. The blood flows were 142 +/- 58 mL/ min(mean +/- SD) in the basilar artery, 229 +/- 86 mL/min in the left, 223 +/- 58 mL/min in the right internal carotid artery, and tCBF was 617 +/- 128 mL/min(Ref. Magn Resn Imaging 14:P. 1143, 1996). Significant increases were observed in head-size-related change of VFR in the basilar artery and height-related change of tCBF. The value of rCBF was easily acquired in combination with SPECT. Phase-contrast MRI is useful for a noninvasive and rapid analysis of cerebral VFR and has potential for clinical use.

[Metabolic imaging of human brain tumors: H-1 chemical shift imaging and PET]

Positron Emission Tomography(PET) and Proton Chemical Shift Imaging(1H-CSI) has provided a cerebral metabolism. The glucose analog fluorine-18 fluorodeoxy-glucose(FDG) and amino acid analog 11C-L-methionine is the most commonly used PET tumor tracer. This time we compare with 1H-CSI and PET in gliomas and metastatic brain tumor with computer-assisted fusion images. We experienced some cases of the brain tumor. One case is metastatic brain tumor after radiation therapy, localized in right parietal hemisphere, with hemorrhage, and slightly accumulated Gd-DTPA in tumors. 11C-methionine PET demonstrates defects in tumors, but slight accumulated surrounding tumors. Accumulation of PET lesion is not elevated choline in CSI, but lactate is accumulated in tumors. Choline signal elevation seen in brain neoprasms, associated with increased cellular proliferation. Accumulation of PET and another accumulation of lactate in tumor are not demonstrate recurrence. Fusion image of PET and CSI is useful in understanding metabolism of brain tumor.

Evaluation of blood flow patterns of true and false lumens in dissecting aneurysms using MR phase-contrast techniques

The magnetic resonance phase-contrast technique for the measurement of flow velocity and volume in true and false lumens was studied in six patients with chronic dissecting aneurysms. Phase-contrast images were obtained at a level perpendicular to the dissecting aneurysms of the descending aorta. As the maximum diameter of aneurysms increased, the ratio of the cross-sectional area of the false to the true lumen increased and the peak average velocity in the true lumen during systole was decreased. This technique proved invaluable for determining prognosis and operability for this condition.

Contrast-enhanced MRI with gadodiamide injection in rabbit carcinoma models

This study was designed to demonstrate the broad utility of contrast-enhanced magnetic resonance imaging (MRI) for diagnosis of carcinoma. Twenty-six New Zealand White rabbits of either sex (1.7-3.4 kg) were used for the investigation. VX2 carcinoma (squamous cell carcinoma) was implanted in either the brain, lung, ovary, bone or muscle of rabbits. Contrast agent, Gadodiamide Injection, was administered intravenously at a dose of 0.1 mmol/kg. MR images were obtained by a 1.5 T, or a 2.0 T magnetic field strength super-conductive MRI unit. The intensity of the signal for the carcinoma was increased after administration of contrast agent, and the detectability or diagnostic information of post-contrast images was superior to that of pre-contrast images in all models. In addition, no significant side effects were observed during the MRI examination. After diagnosis using MRI, morphological damage in each model was assessed by gross and histopathological examinations. In contrast-enhanced MRI, though there were variations between the models employed, contrast effects in brain and muscle carcinoma models were generally related to differences in capillary permeability, while imaging in lung, ovary and bone carcinoma models was dependent on differences in blood flow rate and the size of interstitial spaces. Overall, our results demonstrate that contrast-enhanced MRI is a useful and safe method for diagnosing tumors.

Contrast-enhanced MRI with gadodiamide injection in rat disease models

The present study was designed to confirm the usefulness of contrast-enhanced magnetic resonance imaging (MRI) in diagnosing strokes of stroke-prone spontaneously hypertensive rats (SHRSP) and middle cerebral artery (MCA) occlusion, hepatocellular carcinoma and hydronephrosis of each experimental rat model. Male Sprague-Dawley rats (250-500 g), male SHRSP (ca. 250 g) and male F344 rats (ca. 300 g) were used for the investigation. Gadodiamide injection (Omniscan, Daiichi Pharmaceutical Co., Ltd. and Nycomed AS, Norway) was administered intravenously as the contrast agent at a dose of 0.1 mmol/kg except in hydronephrosis, where a dose of 0.05 mmol/kg was used. Magnetic resonance (MR) images were obtained with a 1.5T or a 2.0T magnetic field strength MRI unit. The signal intensity of the stroke lesions was increased after administration of gadodiamide injection in SHRSP and MCA-occluded rats. Hepatocellular carcinoma was undetectable without the use of the contrast agent, but the signal intensity of the tumor increased after administration of the gadodiamide injection, allowing the lesions to be detected. The signal intensity of the renal medulla increased in the non-ligated kidney, but not in the hydronephrotic kidney. The information given by the post-contrast images were superior to those obtained from the pre-contrast images in all the models. Contrast effects in SHRSP and MCA-occluded rats were related to differences in capillary permeability, those in rats with hepatocellular carcinoma depended on differences in vascularity, and those in hydronephrotic rats depended on blood flow and permeability.

Three-vessel study of cerebral blood flow using phase-contrast magnetic resonance imaging: effect of physical characteristics

The development of phase-contrast magnetic resonance imaging (P-C MRI) provides a noninvasive method for measurement of volumetric blood flow (VFR). We performed P-C MRI to study the effects of physical characteristics on cerebral blood flow. VFR of the left and right internal carotid arteries and basilar artery were measured using P-C MRI and total cerebral blood flow (tCBF) was calculated by summing up the VFR values in the three vessels. Moreover, we investigated the changes in these blood flows as influenced by age, head size, height, weight, body surface area, and handedness. The blood flows were 142 +/- 58 ml/min (mean +/- standard deviation) in the basilar artery; and 229 +/- 86 ml/min in the left, and 223 +/- 58 ml/min in the right internal carotid artery; and tCBF was 617 +/- 128 ml/min. Significant increases were observed in head size-related change of VFR in the basilar artery (p = .028) and height-related change of tCBF (p = .045). The other characteristics did not significantly influence any VFR. The results suggest that head size and height may reflect CBF, and that these effects should be considered when changes of CBF are diagnosed. Phase-contrast MRI is useful for a noninvasive and rapid analysis of cerebral VFR and has potential for clinical use.

Noninvasive analysis of water movement in rat testis using deuterium magnetic resonance imaging

To measure water movement in the testis without the effects from the blood-testis barrier, we performed in vivo deuterium magnetic resonance imaging (2H MRI) of rats administered with deuterated saline. Alcohol was injected into one testis of each animal and the other was administered with normal saline as a control. Dynamic 2H MRI was obtained at 2 T by FLASH pulse sequence (TR, 300 ms; TE, 10 ms; alpha = 90 degrees) using a surface coil (3 cm in diameter). The variation in 2H signal intensity between the two testes as a function of time after deuterated saline injection was examined every 1.1 min up to 20 min. The signal intensity in the testis receiving the alcohol treatment was lower than that in the normal control. Thus, deuterium MRI can be used to analyze functional disorders of the testis.

Differences in metabolic and morphological reactions after radiation therapy: proton NMR spectroscopy and imaging of patients with intracranial tumors

PURPOSE

The purpose of the present study was to detect tumor cell viability, the diagnosis of which is the most important point in clinical therapy for malignant tumors. The advent of localized proton spectroscopy has made this detection possible. The spectral peak intensities were found to be very different depending on tumor tissue pathology.

METHODS

The tumor cell reaction after radiation therapy was examined with proton localized spectroscopy in addition to enhanced MR imaging using a 1.5 Tesla MR system (Philips, Gyroscan S15-HP). Plain MR images (short spin echo) were used for localization pilot images, and after the MRS study, contrast enhanced MRI was carried out. Studies were performed pre-radiation, mid-radiation, and post-radiation if possible.

MATERIALS

Sixteen patients (total 27 examinations) with intracranial tumors and three normal volunteers underwent proton NMR localized spectroscopy. The brain tumors were diagnosed before the MR study, and nine patients had metastatic brain tumors, such as adenocarcinoma, squamous cell carcinoma, and small cell carcinoma, and seven other patients were diagnosed with glioma-type tumors.

RESULTS

The reaction patterns of proton NMR spectroscopy of brain tumors after radiation therapy were very different and depended on tumor histology.

CONCLUSION

Proton NMR spectroscopy is an excellent means of determining tumor cell viability.

Deuterium MR in vivo imaging of the rat eye using 2H2O

In vivo deuterium MR imaging (2H MR) was investigated in rats after intraperitoneal administration of deuterated saline, and a dynamic study of the water movement in rat eyes was performed. Deuterium MR imaging was carried out by means of a gradient-echo (GRE) and a spin-echo (SE) pulse sequence. The rat eye was imaged in 2H MR more selectively by SE than by GRE, but a lower signal-to-noise ratio was obtained in 2H MR imaging using the SE sequence. The MR signal intensity of the rat eye was followed by a 3-compartment model, which enabled determination of the flow rate constant of the water in the eye (0.359/min). Deuterium MR imaging is useful to visualize the dynamic change of water in rat eyes using 2H MR at the same magnetic field (2 T) that can also be used for conventional MR imaging in humans.

Deuterium magnetic resonance imaging of rabbit eye in vivo

We used deuterium magnetic resonance imaging (2H MRI) to visualize water movement in the rabbit eye. Dynamic 2H MRI was obtained every 3.5 min at 2 tesla by FLASH pulse sequence (TR, 300 ms; TE, 10 ms; alpha = 90 degrees) with a slice thickness of 10 mm using a surface coil (4 cm in diameter). After topical administration (0.2 ml D2O), only the aqueous chamber was imaged, and the signals decreased mono-exponentially. The flow rate was 0.113/min, in agreement with that already reported. After intravenous administration of deuterated saline (3 ml/kg), the aqueous chamber became visible first during imaging, then by the vitreous body. The signals around the lens were only faintly detected. Thus, deuterium MRI was determined to be useful for visualizing water movement in the eye.

The functional staging of Duchenne muscular dystrophy using in vivo 31P MR spectroscopy

We applied 31P magnetic resonance spectroscopy (MRS) for the diagnosis of Duchenne muscular dystrophy (DMD), and evaluated its suitability for early-state DMD diagnosis. The spectral patterns showed typical differences between normal and diseased calf muscle. The signal intensity from each spectrum became weaker with advancing disease stage. We could detect abnormality even at the before imaging modalities.

Serial water changes in human skeletal muscles on exercise studied with proton magnetic resonance spectroscopy and imaging

In vivo 1H-magnetic resonance imaging (MRI) enabled us to study the distribution of water in living tissues and to document changes in human skeletal muscles during physical exercise. The purpose of the present study was to determine the total muscle water changes after exercise using water in 1H-MR spectroscopy and to compare these changes to the signal intensity change on T2*-weighted images and/or to the T2 value change. Seven young male volunteers were positioned in a 1.5 T Philips MR imaging system. They were then asked to dorsiflex their ankle joint against a 2 kg weight once every 2 seconds for 2 minutes. The peak height of water declined according to the clearance curve after exercise in all seven cases with the 1H-MRS similar to the signal intensity. The increasing rate at peak height of total muscle water exceeded both the signal intensity and the T2 value because the water peak height on the 1H-MRS included the extracellular water. In addition, we measured the changes in signal intensity in both calf muscles after walking race exercise. The time intensity curves were used to draw a clearance curve for each muscle group after exercise. It was possible to discern which muscle was used most from the T2*-weighted image that was obtained once after exercise.

[Magnetic resonance imaging in multiple system atrophy]

We studied 18 patients with multiple system atrophy (MSA) by high field strength MRI: 6 striatonigral degeneration (SND), 4 Shy-Drager syndrome (SDS), and 8 olivo-ponto-cerebellar atrophy (OPCA). We also studied 30 Parkinson's disease (PD) and 10 age-matched controls. The diagnoses of SND, SDS, and OPCA were based on criteria after Hirayama et al (1985). Bradykinesia, rigidity, and tremor were assessed with the summed scores of the signs used as the extrapyramidal scores. The mean extrapyramidal scores were not significantly different in patients with SND, SDS, OPCA, and PD. MRI studies were performed on 1.5 tesla MRI unit, using a T2 weighted spin echo pulse sequence (TR2500 ms/TE40 ms). The width of the pars compacta signal in all subjects was measured by the method of Duguid et al (1986). Intensity profiles were made on a straight line perpendicular to the pars compacta through the center of the red nucleus on an image of the midbrain. We measured the width of the valley at half-height between the peaks of intensity representing the red nucleus and the crus cerebri-pars reticulata complex and used this measurement as an index of the width of the pars compacta signal. The mean widths of the pars compacta signal were: 2.8 +/- 0.4 mm (SND), 2.8 +/- 0.7 mm (SDS), 3.6 +/- 0.6 mm (OPCA), 2.7 +/- 0.3 mm (PD), and 4.3 +/- 0.6 mm (control). The mean widths of the pars compacta signal in PD, SND, and SDS were significantly narrower than that in the control group (p < 0.05), while the OPCA group was not significantly narrower.(ABSTRACT TRUNCATED AT 250 WORDS)

[Development of a gel phantom for dose distributions by MR imager]

We reported a method of determining spatial dose distributions in tissue-equivalent phantoms using nuclear magnetic resonance imaging. To make a gel phantom, a cross-linked dextran gel (Sephadex G-200) was used as fixation agent of a ferrous sulphate solution. Although high quality images are obtained, the cost is very expensive to make the gel. We developed a new gel which is combined with an extra water absorbent polymer (Sumikagel N-100) and Sephadex G-200. The gel permits the determination of dose distributions for three dimensional treatment planning.

High-energy phosphate metabolism of the myocardium in normal subjects and patients with various cardiomyopathies--the study using ECG gated MR spectroscopy with a localization technique

Nuclear magnetic resonance spectroscopy (MRS) is a new technique for the evaluation of myocardial metabolism. Recently, localized MRS has been clinically available to measure by a non-invasive method the relative concentrations of the high-energy phosphate metabolites in the myocardium. We performed ECG gated P-31 MRS using ISIS (image-selected in vivo spectroscopy) in 15 normal volunteers, 12 patients with hypertrophic cardiomyopathy, 12 with left ventricular hypertrophy, 6 with dilated cardiomyopathy and 11 with specific heart muscle disease. Myocardial peak height ratios of PCr/gamma-ATP, Pi/gamma-ATP and PCr/Pi were measured. Myocardial P-31 MRS demonstrated a significant decrease in the ratio PCr/ATP in patients with hypertrophic cardiomyopathy and specific heart muscle disease as compared with normal subjects, indicating myocardial metabolic disturbance in these patients. The ratio of PCr/ATP in patients with dilated cardiomyopathy did not differ significantly from that of normal subjects. However, exercise MRS revealed a marked decrease of PCr peak in an asymptomatic patient with dilated cardiomyopathy, which may indicate a latent metabolic disturbance in the myocardium of dilated cardiomyopathy.

[Intramuscular degeneration process in Duchenne muscular dystrophy--investigation by longitudinal MR imaging of the skeletal muscles]

Intramuscular degeneration process of Duchenne dystrophy skeletal muscles was investigated by longitudinal skeletal muscle imaging with high-field-strength NMR-CT of 1.5 Tesla. Thigh muscles in 10 cases ranging in age from 4 to 19 years were examined by T1-weighed longitudinal images (TR = 215-505 ms, TE = 19-20 ms). Following results were obtained: (1) Skeletal muscle degeneration was depicted as high signal intensity area reflecting its high fat contents. (2) These high signal intensity areas had a longitudinally streaky appearance in parallel direction with myofibers. (3) These findings were more prominent toward myotendon junction than muscle bellies. (4) Skeletal muscle degeneration progressed rapidly between 7 to 10 years of age, and reached a plateau after that.

Dynamic human glycogen and glucose metabolism detection utilizing in vivo 13C NMR

The dynamic detection studies of glucose-glycogen metabolism of the human liver were performed with normal volunteers. A single tuned surface coil of 20-cm diameter was used for 13C (at 16.04 MHz). Natural glucose 100 g was administered for the natural abundance 13C MR dynamic study and 13C enriched (99%) 1-13C-D-glucose 1 g mixed 75 g glucose was administered to study the 13C enrichment effect. The total scan time of this dynamic study was 1 hr and each single scan time was 20 min. We did not use proton decoupling for the human 13C MR study. Localized (PRIME) proton shimming was performed and the shim value was less than 20 Hz. Glucose and glycogen spectra were clearly visible at 120 to 80 ppm and about 3 hr later both peaks almost disappeared. These data demonstrate that dynamic hepatic glucose-glycogen metabolism should be possible to detect which should allow for the direct diagnosis of hepatic glucose-glycogen metabolic disorders.

[MRI in Parkinson's disease and vascular parkinsonism--study on the lesion of substantia nigra]

We examined the magnetic resonance (MR) image of midbrain and striatum in 30 patients with Parkinson's disease (PD), 10 patients with vascular parkinsonism (VP) and 10 age-matched control subjects. Studies were performed on a high field strength (1.5 tesla) MRI unit. T2 weighted spin echo pulse sequence (TR2500ms/TE40ms) was used. We measured the width of the pars compacta signal in patients and controls on the basis of the method described by Duguid et al. Intensity profiles of a straight line perpendicular to the pars compacta through the center of the red nucleus were made on an image of the midbrain. We measured the width of the valley at half-height between the peaks of intensity representing the red nucleus and the crus cerebri-pars reticulata complex and used this as an index of the width of the pars compacta signal. The results were as follows: 1. The mean width of the pars compacta signal was 2.7 mm (SD = 0.3) in the PD group and 4.3 mm (SD = 0.6) in controls. The difference between the means was highly significant (p less than 0.01). While not significant statistically, there was a trend toward narrowing of the width of pars compacta signal of substantia nigra in the PD group as the Yahr's grade or disease duration progressed. In hemiparkinsonism, MRI revealed significant narrowing of the pars compacta signal on the contra-lateral side to the clinical predominant side compared with the ipsi-lateral side. 2. The mean width of the pars compacta signal was 3.9 mm (SD = 0.4) in the VP group, but the decrease was not significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Quantitative measurement of uptake of radiolabeled monoclonal antibody by means of planar data

Data obtained from planar images were used to measure the uptake of monoclonal antibody in organs and tumors. Background counts included in the region of interest were eliminated, and the attenuation of the photons emitted by the radionuclide through the intervening tissues was compensated for. The background counts and the intensity of the attenuation were determined from the results of phantom studies and numerical integration with a personal computer. The quantitative uptake of 111In labeled anti-melanoma Monoclonal Antibody (ZME-018) in a melanoma lesion, the liver, and the bone marrow of a patient was measured by the planar method which we developed.

Study of biodistribution of enflurane in rats with in vivo 19F MRI

In vivo 19F magnetic resonance imaging (MRI) of anesthetized rats enabled us to visualize the biodistribution of fluorinated anesthetics and to document the changes in MR signals in the body during the induction and the elimination phase of anesthesia. The authors examined in vivo 19F MRI in rats anesthetized with concentrations of 1.75-2.0% enflurane and demonstrated its in vivo distribution with concomitant 1H and 13C MRI to verify the anatomical correlation. Distinct 19F MR signals were acquired predominantly from the systemic adipose tissue and the liver. Additionally, the temporal changes in the tissue during and after anesthesia were characterized with in vivo 19F MRI in 6.4 min of the acquisition time. The 19F MR signals increased with time after anesthesia; however, the signals from the adipose tissue were apparently stronger than those from the liver. Following the discontinuation of inhalation, the MR signals in the liver decreased far more rapidly than those from the adipose tissue. When the animal woke up and began to move, the MR signals were still visible in the adipose tissue. These results confirmed the fact that enflurane dissolves preferentially in the adipose tissue and remains when the anesthetic effect disappears. Additionally, 19F MR signals of the liver during the elimination phase might reflect the concentration of enflurane in the blood.