The effect of acquisition interval and spatial resolution on dynamic cardiac imaging with a stationary SPECT camera

The current SPECT scanning paradigm that acquires images by slow rotation of multiple detectors in body-contoured orbits around the patient is not suited to the rapid collection of tomographically complete data. During rapid image acquisition, mechanical and patient safety constraints limit the detector orbit to circular paths at increased distances from the patient, resulting in decreased spatial resolution. We consider a novel dynamic rotating slant-hole (DyRoSH) SPECT camera that can collect full tomographic data every 2 s, employing three stationary detectors mounted with slant-hole collimators that rotate at 30 rpm. Because the detectors are stationary, they can be placed much closer to the patient than is possible with conventional SPECT systems. We propose that the decoupling of the detector position from the mechanics of rapid image acquisition offers an additional degree of freedom which can be used to improve accuracy in measured kinetic parameter estimates. With simulations and list-mode reconstructions, we consider the effects of different acquisition intervals on dynamic cardiac imaging, comparing a conventional three detector SPECT system with the proposed DyRoSH SPECT system. Kinetic parameters of a two-compartment model of myocardial perfusion for technetium-99m-teboroxime were estimated. When compared to a conventional SPECT scanner for the same acquisition periods, the proposed DyRoSH system shows equivalent or reduced bias or standard deviation values for the kinetic parameter estimates. The DyRoSH camera with a 2 s acquisition period does not show any improvement compared to a DyRoSH camera with a 10 s acquisition period.

Comparison of gross tumor volume delineated by anatomic imaging and FDG PET/CT for esophageal carcinoma and validation with pathological specimen

15090

Background: Although results of clinical studies have demonstrated FDG PET/CT improved target volume delineation in various tumors, only few studies compared delineation based on PET/CT with pathologic examination. Aim of our study was to compare anatomic imaging modalities including computed tomography (CT), esophagram, endoscopy with FDG PET/CT for delineation of gross tumor volume (GTV) in esophageal carcinoma and to validate the results with the pathologic examination. Methods: Thirty patients with stages II-III squamous cell carcinoma underwent transthoracic esophagectomy were enrolled. PET/CT, esophagram and endoscopy were performed with patients before operations. The length of the lesion on the PET/CT scan and on the CT portion of the PET/CT and the PET scan alone was determined independently by 3 separate investigative groups. PET/CT scan was evaluated by visual inspection for abnormality. A standard uptake value (SUV) of 2.5 was used in the PET scan to delineate the tumor extent. The lengths of GTVs determined with the five modalities (PET/CT, PET, CT, esophagram and endoscopy) were compared quantitatively and validated with the pathologic specimen. The sizes of the tumors were measured by pathologic examination which was considered as the gold standard. Results: Of the 30 patients, 9 had T2 tumors, 20 had T3 tumors and 1 had T4 tumor with an involvement of pleura. Three tumors were located at the upper esophagus, 14 at the middle esophagus, 13 at the lower esophagus. The mean length of the carcinoma was 5.85cm(SD 2.50cm) measured by pathologic examination, 5.79cm (SD 2.04cm) as determined by PET scan, 5.14cm (SD 1.65cm) by PET/CT scan, 5.42 cm(SD 2.42cm)by CT scan, 5.50cm(SD 2.79cm) by endoscopy, and 6.07cm(SD 2.75cm) by esophagram respectively. Although the lengths of the tumors as measured by the five imaging modalities were no significant difference, the result of PET was the most accurate. Conclusions: Compared with tumor lengths measured by pathologic examination, PET with a SUV 2.5 was found to be the most accurate modality and can help the radiation oncologist delineate the GTV of esophageal carcinoma precisely.

No significant financial relationships to disclose.

The human lung: did evolution get it wrong?

Some 300 million yrs ago, the ancestors of modern reptiles emerged from water and were committed to air breathing. They were exothermic and incapable of sustained levels of high physical activity. But from them evolved the two great classes of vertebrates with high levels of maximal oxygen consumption: the mammals and birds. A remarkable feature of these two divergent evolutionary lines is that, although the physiology of many organ systems shows many similarities, the lungs are radically different. A major difference is that the ventilation of the gas-exchanging tissue has a flow-through pattern in the bird but is reciprocating in the mammal. The result is that mammals have a reduced alveolar and arterial oxygen tension, a potential for uneven ventilation, and relatively large terminal air spaces. This in turn means that the pulmonary capillaries are poorly supported compared with the bird. The result is that the pulmonary capillaries in the bird have much thinner and more uniform walls, with more efficient gas exchange. Other advantages of the bird lung are that it utilises a more efficient cross-current pattern of gas-exchange, and the bird has separated the ventilatory and gas exchange functions. From a structure-function standpoint, the bird lung is superior.

A randomized clinical study of surgery versus radiotherapy in the treatment of resectable esophageal cancer

4013

Background: To compare the treatment results between radical surgery and late-course accelerated hyperfractionation radiotherapy (LCAHFR) for patients with resectable thoracic segment esophageal cancer. Methods: From June 1998 to September 2002, 269 patients with resectable thoracic esophageal cancer were randomized into two groups. 135 were with surgery and 134 with late-course accelerated hyperfractionated (LCAF) radiotherapy. Chemotherapy only for clinical recurrence and salvage therapy. Results: The 1-, 3- and 5- year overall survival rate were 88.6%, 56.2% and 34.7% in the surgery group and 93.3%, 61.5% and 36.9% in the radiotherapy group. There was no statistical difference between the two groups (P =0.58). Median survival was 28.5 months and 30.5 months respectively. The 1-, 3-and 5-year progression-free survival rate was 73.3%, 39.7% and 20.6% in the surgery group and 75.9%, 43.7% and 23.1% in the radiotherapy group (P =0.65) . There was no difference between the two groups in survival rates including different location and length (P > 0.05). The incidence of failure by hematogenous metastasis and distant lymphatic metastasis in the radiotherapy group (16.6% and 13.3% respectively ) was lower than in the surgery group ( 25.3% and 20.3 % respectively ), there was no significance between them. The incidence of local failure in the radiotherapy and surgery group was 57.3% and 27.8% respectively (P = 0.001) The incidence of death by local reasons was higher than in the surgery group (P = 0.02 ). The incidence of death by distant metastasis was lower than in the surgery group (P = 0.02 ). Conclusion: The treatment results between radical surgery and LCAHFR with conformal radiotherapy for patients with resectable thoracic esophageal cancer were comparable.

No significant financial relationships to disclose.

The GATA site-dependent hemogen promoter is transcriptionally regulated by GATA1 in hematopoietic and leukemia cells

Hemgn (a gene symbol for hemogen in mouse, EDAG in human and RP59 in rat) encodes a nuclear protein that is highly expressed in hematopoietic tissues and acute leukemia. To characterize its regulatory mechanisms, we examined the activities of a Hemgn promoter containing 2975 bp of 5' flanking sequence and 196 bp of 5' untranslated region (5' UTR) sequence both in vitro and in vivo: this promoter is preferentially activated in a hematopoietic cell line, not in nonhematopoietic cell lines, and is sufficient to drive the transcription of a lacZ transgene in hematopoietic tissues in transgenic mice. Mutagenesis analyses showed that the 5' UTR including two highly conserved GATA boxes is critical for the promoter activity. GATA1, not GATA2, binds to the GATA binding sites and transactivates the Hemgn promoter in a dose-dependent manner. Furthermore, the expression of human hemogen (EDAG) transcripts were closely correlated with levels of GATA1 transcripts in primary acute myeloid leukemia specimens. This study suggests that the Hemgn promoter contains critical regulatory elements for its transcription in hematopoietic tissues and Hemgn is a direct target of GATA1 in leukemia cells.

Prenatal echocardiographic differential diagnosis of fetal cardiac tumors

OBJECTIVES

To present data on echocardiographic findings of fetal cardiac tumors and discuss their differential diagnoses.

METHODS

We retrospectively reviewed 14 cases of fetal echogenic cardiac mass diagnosed between 1990 and 2003; 12 were confirmed to be cardiac tumors and two were false-positive diagnoses. The echocardiographic characteristics examined included number, size, location and associated complications.

RESULTS

Eight fetuses had a single tumor and four fetuses had multiple tumors. The left ventricle was most often affected. Parents of eight fetuses opted for termination of pregnancy, one fetus died in utero and three affected fetuses survived. Histopathological examination revealed cardiac rhabdomyoma in six fetuses, fibroma in two, teratoma in two, lipoma in one and hemangioma in one. The pitfalls associated with prenatal echocardiographic diagnosis of cardiac tumors include: they may be too small to be visualized, intracardiac echogenic foci may mimic tumors, and echogenicity resulting from extracardiac structures or neoplasms near the heart may falsely appear as tumors.

CONCLUSION

Fetal cardiac tumors can be detected by echocardiography. However, differential diagnosis is important as this will affect prognosis and subsequent management.

Nutritional and hormonal factors control the gene expression of FoxOs, the mammalian homologues of DAF-16

Transcription factors of the FoxO family in mammals are orthologues of the Caenorhabditis elegans forkhead factor DAF-16, which has been characterized as a target of insulin-like signalling. Three members of this family have been identified in rodents: FoxO1, FoxO3 and FoxO4, originally termed FKHR, FKHRL1 and AFX respectively. A number of in vitro studies have revealed that FoxOs are regulated through phosphorylation in response to insulin and related growth factors, resulting in their nuclear exclusion and inactivation. To clarify the mechanisms involved in the regulation of these factors in vivo, we investigated in the present study whether or not, and if so how, their mRNA levels in rat liver respond to the stimuli of several nutritional and hormonal factors. Imposed fasting for 48 h significantly elevated mRNA levels of FoxO1 (1.5-fold), FoxO3 (1.4-fold), and FoxO4 (1.6-fold). Refeeding for 3 h recovered the induced mRNA levels of FoxO1 and FoxO3 to the control levels, but did not affect that of FoxO4. FoxO1 and FoxO4 mRNA levels were proved to be highly reflective of their protein levels measured by Western immunoblotting. Of the three FoxO genes, FoxO4 only showed altered levels of mRNA (a 1.5-fold increase) in response to a protein-free diet. Streptozotocin-induced diabetes for 28 days decreased hepatic mRNA levels of FoxO1 and FoxO3 and increased the level of FoxO4 mRNA, but short-term (7 days) diabetes had fewer effects on the expression of these genes. Insulin replacement partially restored the FoxO1 and FoxO4 mRNA levels, but had no effect on the FoxO3 mRNA level. Daily administration for 1 week of dexamethasone, a synthetic glucocorticoid, increased the mRNA levels of FoxO1 (1.8-fold) and FoxO3 (2.4-fold). These results show that the FoxO genes respond differently to nutritional and hormonal factors, suggesting a new mechanism for the regulation of FoxO-dependent gene expression by these factors. Moreover, changes of FoxO1 and FoxO4 in the nucleus in response to fasting also suggest that the regulation of nucleus/cytoplasm translocation actually functions in vivo.

Routine screening mammography: how important is the radiation-risk side of the benefit-risk equation?

The potential radiation hazards associated with routine screening mammography, in terms of breast cancer induction, are discussed in the context of the potential benefits. The very low energy X-rays used in screening mammography (26-30 kVp) are expected to be more hazardous, per unit dose, than high-energy X- or gamma-rays, such as those to which A-bomb survivors (from which radiation risk estimates are derived) were exposed. Based on in vitro studies using oncogenic transformation and chromosome aberration end-points, as well as theoretical estimates, it seems likely that low doses of low-energy X-rays produce an increased risk per unit dose (compared with high energy photons) of about a factor of 2. Because of the low doses involved in screening mammography, the benefit-risk ratio for older women would still be expected to be large, though for younger women the increase in the estimated radiation risk suggests a somewhat later age than currently recommended--by about 5-10 years--at which to commence routine breast screening.

Relationship of large multifunctional proteasome 7 gene polymorphism with susceptibility to type 1 diabetes mellitus and DR3 gene

OBJECTIVE

To study the relationship of the large multifunctional proteasome 7 (LMP7) gene polymorphism with susceptibility to type 1 diabetes mellitus (DM-1) and the DR3 gene in south Chinese Han population.

METHODS

LMP7 genotypes and the DR3 gene were identified in 71 DM-1 patients and 86 healthy persons (as controls) by polymerase chain reaction-restriction fragment length polymorphism. DM-1 patients and controls were divided into DR3-positive and DR3-negative subjects. The frequencies of LMP7 genotypes and alleles were compared between DM-1 patients and controls respectively in the random subjects and in the DR3-matched subjects. Furthermore, DM-1 patients were divided into 3 groups according to the age of diabetic onset: group A < or = 14 years, group B 15-30 years, group C > or = 31 years.

RESULTS

In the random subjects, the frequency of LMP7-B/B was lower (39% vs 58%, P < 0.05) and that of LMP7-B/A was higher (54% vs 31%, P < 0.01) in DM-1 patients than that in controls. In DR3-positive subjects, the frequencies of LMP7 genotypes and alleles showed no differences between DM-1 patients and controls. In DR3-negative subjects, the frequency of LMP7-B/B was decreased (40% vs 61%) and that of LMP7-B/A was increased (55% vs 28%, P < 0.01) in DM-1 patients. The frequencies of LMP7 genotypes and alleles showed no significant differences among different ages of diabetic onset.

CONCLUSIONS

LMP7-B/B may be the protective genotype, and LMP7-B/A may be the susceptible genotype of DM-1, and this may not be affected by the DR3 gene. Persons with LMP7-B/B may have a decreased risk, and those with LMP7-B/A have an increased risk suffering from DM-1. The LMP7 gene may not be associated with the age of diabetic onset.

[Protective effect of huyin decoction on acute hepatic injury induced by CCl4 in mice]

OBJECTIVE

To observe the protective effect of Huyin decoction on acute hepatic injury induced by CCl4 in mice.

METHODS

The model of acute hepatic injury induced by CCl4 was used. The levels of ALT and AST in serum were detected. And histopathology of liver was observed.

RESULTS

Huyin decoction could decrease ALT and AST in serum and hepatic histopathological injury of the acute hepatic injury mice.

CONCLUSION

Huyin decoction possessed protective effect on acute hepatic injury in mice.

Proline-based P, N ligands in asymmetric allylation and the Heck reaction

A series of phosphine-oxazoline ligands based on proline are reported. These ligands are synthesized from commercially available trans-4-hydroxy-L-proline in four steps. The ability of this type of ligand to catalyze allylic alkylation in an asymmetric fashion as well as the asymmetric Heck reaction is reported. The best of these ligands gave a palladium complex, which catalyzed the addition of dimethylmalonate to cyclopentenyl acetate in excellent yield and up to 96% ee. This same system catalyzed the Heck reaction between dihydrofuran and cyclohexene in up to 86% ee. These ligands appear to differ from the traditional phosphine-oxazoline ligands in that the stereochemistry of the stereogenic carbon next to the oxazoline is not necessarily the dominant chiral center in the induction of selectivity.

Regulation of hydroxyindole-O-methyltransferase gene expression in Japanese quail (Coturnix coturnix japonica)

Hydroxyindole-O-methyltrasferase (HIOMT) plays an important role as the final enzyme in the synthesis of melatonin. In this study, the expression of the HIOMT gene in Japanese quail was investigated with respect to tissue distribution and the effects of light and vitamin A deficiency. HIOMT mRNA in the pineal gland and eye had a clear daily rhythm with peak values in daytime. The testis also contained a detectable amount of HIOMT mRNA, which did not display a rhythmic change over a 24-h period. When birds were rendered vitamin A deficient through feeding with a vitamin A-free diet, the daily rhythm of the HIOMT gene almost disappeared in both the pineal gland and eye due to increases in the nighttime values. Our previous observations and these results suggest that vitamin A and a photo-signal are required to maintain the rhythmic expression of the HIOMT gene as well as the arylalkylamine N-acetyltransferase gene.