Measurement of the liver and spleen volume by single photon emission computed tomography

Organ volume was experimentally and clinically determined using single photon emission computed tomography (SPECT). In organ phantom filling with 99mTcO4-, the error was less than 3.3% in the volume over 400 ml but 11% at 200 ml. In 28 cases of patient, liver and spleen volume were measured by SPECT and X-CT. Good correlation was founded between SPECT volume and X-CT volume (r = 0.99, n = 49), although SPECT volume were 16% higher than X-CT volume (y = 1.16 x + 11.6, x: X-CT volume, y: SPECT volume).     

Estimation of 99mTc-dimercaptosuccinic acid renal uptake using single photon emission computed tomography

Renal function was assessed by measurement of 99mTc-dimercaptosuccinic acid (DMSA) uptake by the kidney based on the transsectional tomographic image obtained by single photon emission computed tomography (SPECT). The renal uptake was expressed as percentage of the total radioactivity detected in the kidney, the volume of which was measured by convolution method, against the amount dosed. Absorption was corrected by GE-STAR method using cut off level of 42%. In order to determine normal range, measurement was made for 40 kidneys of each of 10 male and female volunteers confirmed of having normal kidneys both morphologically and functionally. The average volume of the kidney was 220.4 ml for the right and 239.3 ml for the left for males, and 205.9 ml and 236.5 ml, respectively for females. The renal uptake of radioactivity (at 2 h after injection), was 26.8% for the right and 27.6% for the left for males, with corresponding figures for females being 26.4% and 27.9%, respectively. Distribution range of renal volume and renal uptake was obtained by bivariate analysis with 90% and 95% probability. From these results, our method of renal function determination based on renal uptake of 99mTc-DMSA obtained from renal transactional tomogram by SPECT is considered to be accurate and potentially useful for clinical purpose.     

Performance of gamma camera collimators used for single photon emission computed tomography imaging with 123I-isopropyl iodoamphetamine

123I Produced by 124Te(p, 2n)123I reaction is contaminated with 124I (less than 5%) and 126I (less than 0.3%). High energy photons from these mixed radioiodine compromise seriously image quality due to scattered photons and to septal penetration in the collimator. Four collimators of LEAP (for low energy all purpose), LEHR (for low energy high resolution), MESI (for medium energy made by Siemens) and MENU (for medium energy made by nuclear technology) mounted on a rotating gamma camera (Siemens, ZLC-7500), were examined in order to select a suitable collimator for 123I SPECT (single photon emission computed tomography) imaging. Sensitivities were measured with a plane source (5 X 5 X 0.5 cm) at the collimator face and distances from 2 to 30 cm in air. And, spatial resolutions in FWHM (full width at half maximum) and FWTM (full width at tenth maximum) were determined from line spread functions with planar and SPECT imaging. From the comparison of collimator performances with 99mTc and 123I, both collimators for low energy were not useful for 123I imaging. In other two collimators for medium energy, however, apparently the effect of septal penetration by the higher energy photons were also recognized, MENU with high geometrical resolution was more suitable for 123I SPECT imaging compared with MESI. And, it is important to perform the SPECT imaging with radius as short as possible.     

Single photon radioisotope emission computed tomography image using gamma camera (author's transl)]

Single photon radioisotope computed tomography (RCT) images were obtained using the following devices such as conventional gamma camera, data processer for exclusive use of nuclear medicine (C.D.S.-4096), magnetic tape and medium size electronic computer FACOM 230-28S (48K) for multipurposes, which are routinely used for clinical purpose. To reconstruct the RCT image we made absorption correction by geometric mean of opposing counts considering the thickness of source and used the convolution integral method. The reconstructed images of phantom study resolved one centimeter clearly and were very similar to original. The RCT image of patient was acquired by the rotation of patients using the revolving chair and the handmade implement which settles the center of patient's head. Three dimensional informations were obtained by one examination with a gamma camera which collects two dimensional images. When using a gamma camera, therefore, not only a transaxial but an arbitraly RCT image will be important to contribute for diagnosis.     

Clinical usefulness of a dual photon absorptiometry system using X-ray for peripheral bone--comparison with a single photon absorptiometric system

A newly developed dual photon absorptiometry system (DCS-600, ALOKA Co., LTD.) using two monochromatic X-rays for the determination of bone mineral in the peripheral bone was fundamentally studied, in comparison to single photon absorptiometry system (SPA). The accuracy and precision in DCS-600 were equal to or better than SPA system. Furthermore, in DCS-600 the forearm could be imaged, and the manipulation was easy. Thus DCS-600 was found to be a good instrument as a quantifying system of bone mass.     

Study of quantitative evaluation of liver volume and accumulation rate of radioactive agent with single photon emission computed tomography

The quantitative evaluation on measurement of liver volume and the hepatic accumulation rate of the radioactive agent were studied with respect to body constitution, background activity and splenic consumption rate, using single photon emission computed tomography (SPECT). The optical cut-off level for liver volume determination was proved to be reasonable as 35%. The background less than 5% had no influence to their clinical estimation with the error of less than 1.6%. The estimation of liver volume was mostly influenced by the splenic activity. When the splenic activity was increased two times of the hepatic activity, the liver volume was determined as 4.2% larger. Calculated counts by SPECT was well correlated with the hepatic activity. This study proved that SPECT was useful for the quantitative evaluation of the liver volume and the hepatic accumulation rate.     

In vivo imaging of brain dopaminergic neurotransmission system in small animals with high-resolution single photon emission computed tomography.

High-resolution single photon emission computed tomography (SPECT) provides a unique capability to image the biodistribution of radiolabeled molecules in small laboratory animals. Thus, we applied the high-resolution SPECT to in vivo imaging of the brain dopaminergic neurotransmission system in common marmosets using two radiolabeled ligands, [123I]2beta-carbomethoxy-3beta-(4-iodophenyl)tropane (beta-CIT) as a dopamine transporter (DAT) ligand and [123I]iodobenzamide (IBZM) as a dopamine D2 receptor (D2R) ligand. Specific images of the striatum, a region with a high density of dopaminergic synapses, were obtained at 240 min and 60 min after injection of [123I]beta-CIT and [123I]IBZM, respectively. Furthermore, a significantly low accumulation of [123I]beta-CIT in the striatum was observed in MPTP-treated animals compared with results for a control group, and a similar accumulation in the control group was observed with the pretreatment of deprenyl in the MPTP-treated animals. However, the striatal accumulation of [123I]IBZM showed no changes among the control, MPTP-treated, and deprenyl-MPTP-treated groups. These SPECT imaging results agreed well with those of DA concentration and motor behavior. Since MPTP destroys nigrostriatal dopamine nerves and produces irreversible neurodegeneration associated with Parkinsonian syndrome, SPECT imaging data in this study demonstrated that deprenyl shows its neuroprotective effect on Parkinsonism by protecting against the destruction of presynaptic dopamine neurons.     

Charge transfer enhanced annihilation leading to deterministic single photon emission in rigid perylene end-capped polyphenylenes

Two new peryleneimide end-capped polyphenylenes are shown to be deterministic single photon sources in PMMA films due to efficient annihilation between charge transfer states.     

Anatomic characterization of human ultra-weak photon emission with a moveable photomultiplier and CCD imaging

Ultra-weak photon emission of a living system has received scientific attention because of its potential for monitoring oxidative metabolism and oxidative damage to tissues. Heretofore, most studies have focused only on the emission from hands. The data regarding emission from other anatomic locations are limited. A previous multi-anatomic site recording of four subjects quantitatively demonstrated that the emission from several corresponding anatomic locations could differ by as much as a factor of 4. The data also suggested a "common" anatomic emission percentage distribution pattern. This information raised the question whether such a typical anatomic percentage emission exists. The objective of the present paper is to systematically replicate the emission from identical anatomic locations to document whether the anatomic percentage distribution pattern is generic. Part 1 includes the recording of ultra-weak photon emission from one sample subject over the torso, head and upper extremities with a highly sensitive charge-coupled device (CCD). Part 2 includes the analysis of that data to select a series of anatomic locations that were subsequently studied with a group of 20 subjects utilizing a highly sensitive, cooled and moveable (in three directions) photomultiplier system. Total sum emission of all recorded anatomic locations per subject fluctuates in this study almost 5-fold between subjects. However, the contribution of each anatomic location to the total emission from each subject was approximately the same percentage for each subject and similar to the sample CCD subject. The deviation of the anatomic percentage contribution for each subject was also established. The study presents evidence that there is a "common" anatomic percentage distribution pattern of ultra-weak photon emission for corresponding locations from each subject.     

Driving the Bloch vector of a single molecule: towards a triggered single photon source

We propose the method of rapid adiabatic passage to prepare a single molecule in its fluorescing excited state. Spontaneous emission from this state gives rise to a single photon. Since the adiabatic passage can be performed on command, the molecule can be used as a triggered single photon source. Preliminary experiments and quantum Monte-Carlo simulations demonstrate the feasibility of this scheme.     

Subnanosecond single photon timing measurements using a pulsed diode-laser.

The convenient and inexpensive use of a pulsed diode-laser (Hamamatsu Photonics PLP-01 660 nm) is demonstrated as a low cost alternative to a standard pulsed laser or gas discharge flash system in a commercial time-correlated single photon counting instrument. Fluorescence lifetimes of compounds of photobiological interest such as phytochrome, chlorophyll a, 1,1'-diethyl-4,4' carbocyanine iodide (DCI/cryptocyanin),5,10,15,20-tetra(p-phenyl) porphyrin and stentorin I are presented using the pulsed diode-laser source.     

Fullerene ionization dynamics after single photon excitation with synchrotron radiation

Ionization dynamics of free C₆₀ is investigated after single photon excitation with synchrotron radiation in the energy range between 8.9 eV and 27.6 eV. Upper limits for the time constants describing possible delayed ionization are obtained from peak shape asymmetries in time of flight spectra as a function of excitation energy. The results clearly indicate that delayed ionization is not observed after single photon excitation in contrast to the results obtained in ns-laser MPI experiments.     

Variable threshold levels for estimation of renal uptake of 99mTc-dimercaptosuccinic acid based on single photon emission computed tomography

To calculate renal uptake of 99mTc-dimercaptosuccinic acid (DMSA) more accurately using single photon emission computed tomography (SPECT), it is necessary to estimate values of threshold level, which corresponds to the ratio of kidney to background (BG ratio). Thus the phantom and clinical studies were conducted. Six kinds of renal phantoms of 80 to 339 ml, contained different radioactivity of 37 to 485 MBq were prepared. These phantoms were placed in a larger body phantom filled with 1 to 50% of radioactivity representing background. Clinical application of this method was also performed. Results were as follows. 1) A significant correlation between phantom volumes and estimated volumes obtained using threshold level based on BG ratio calculated on tomographic images was found (r = 0.99). 2) A significant correlation between total counts in estimated volumes and radioactivities in phantoms was recognized (r = 0.94). 3) Known radioactivity in phantoms and radioactivity in estimated volumes were highly related (r = 0.98). 4) Clinical application showed valuable results in patients with renal dysfunction. Thus, this method can calculate more accurate renal uptake of 99mTc-DMSA.     

Spectral shift of ultraweak photon emission from sweet potato during a defense response

Consecutive spectral analyses of ultraweak photon emission from sweet potato showing a defense response were conducted to observe the process of physiological transition. The spectrum showed a drastic transition from 2 to 10 h after inoculation with Fusarium oxysporum, during which the emission intensity increased slowly. The spectrum was stable from 10 to 36 h after inoculation, whereas the emission intensity peaked approximately 20 h after inoculation. A change in the physiological state connected with the synthesis of defense-related substances is suggested as contributing to this phenomenon. The spectral transition was also detected in sweet potato treated with growth hormone or exposed to alternating temperature, although with an extremely weak emission intensity. This spectral analysis of ultraweak photon emission can be used as a new means for identifying the physiological state.     

Single molecule photon emission statistics of driven three-level systems

We study the statistics of photon emission from three-level single molecule systems. The generating function method [Y. Zheng and F. L. H. Brown, Phys. Rev. Lett. 90, 238305 (2003)] is used to calculate steady state absorption line shapes and Mandel's Q parameter as a function of excitation frequency, as well as the time dependence associated with approach to the steady state. The line shape calculations confirm known results derived via other methods, while the Q parameter results display complex frequency dependences not amenable to simple interpretation. This study confirms the applicability of the generating function formalism to multilevel quantum systems, including the proper modeling of quantum coherence effects.     

Synthesis and in vitro evaluation of iodinated derivatives of piperazine as a new ligand for sigma receptor imaging by single photon emission computed tomography

A new series of radioiodinated analogues of 1-[2-(3,4-dimethoxyphenyl)ethyl]-4-(3-phenylpropyl)piperazine (SA4503) was synthesized and evaluated as a potential brain sigma-1 receptor imaging ligands by single photon emission computed tomography (SPECT). Iodinated analogues of SA4503 (4a-c) were prepared from piperazine in a high yield. The in vitro competition binding studies using [3H] DTG (sigma-1, 2), [3H] (+)-pentazocine (sigma-1), and [3H] DTG in the presence of carbetapentane (sigma-2) as sigma receptor selective radioligands were revealed that iodinated analogues 4a-c possess high affinities to sigma receptors (IC50: 4a=7.1, 4b=31.0, and 4c=77.3 nM). In particular, the affinity of 4a, bearing iodine at ortho position on the phenyl ring, was 4.4 times greater than SA4503, and 3 times greater than that of haloperidol. The meta-iodo analogue 4b was the same to SA4503, the lead compound. The radioiodinated derivatives, [125I] 4a, 4b were synthesized no-carrier-added from the corresponding tributyltin precursors by the iododestannylation reaction with high yields. The binding of [125I] 4a, 4b have been characterized in the rat brain membranes. These compounds were indicated single population binding to sigma receptor with high affinity (4a: Kd=1.86+/-0.34 nM, Bmax=205+/-28.9 fmol/mg protein, 4b: Kd=3.30+/-0.51 nM, Bmax=231.5+/-13.8 fmol/mg protein). In vitro blocking studies were confirmed that the high specificity of 4a, 4b. These results suggest that radioiodinated 4a and 4b are promising sigma receptors imaging ligand for pursuing further in vivo studies.     

Development of a single photon counting gamma-ray camera for Compton noise elimination

Journal of Radioanalytical and Nuclear Chemistry - In this study, the noise resulting from Compton scattering was quantified when gamma images were acquired with a 50-mm thick scintillator array...     

Production of three radical cations from a single photon using a photo acid generator

Efficient generation of the organic radicals is a fundamental technology for preparing the spintronic materials. In this Letter, we present the chemical reaction of the three radical generation from a single photon. A photo acid generator which can release the multiple acid molecules via the automatic amplification mechanism was synthesized. The synthesized acid generator immediately released methanesulfonic acid by UV irradiation. Due to the amplification system, a maximum of three acid molecules can be produced from the single acid generator. In addition, the release of acid is induced by UV irradiation and automatically proceeds until the release of three acid molecules is finished. Finally, by employing the acid-catalyzed radical generation of tetrathiafulvalene, we also demonstrate the efficient radical generation triggered by UV irradiation in the polymer film.