Retrospective interactive rigid fusion of 18F-FDG-PET and CT

Aim: This study investigates whether interactive rigid fusion of routine PET and CT data improves localization, detection and characterization of lesions compared to separate reading. For this purpose, routine PET and CT scans of patients with metastases from malignant melanoma were used. Patients, methods: In 34 patients with histologically confirmed malignant melanoma, FDG-PET and spiral CT were performed using clinical standard protocols. For all of these patients, gold standard was available. Clinical and radiological follow-up identified 82 lesions as definitely pathological. Two board-certified nuclear medicine physicians and two board-certified radiologists analyzed PET and CT images independently from each other. For each patient up to 32 anatomical regions (24 lymph node regions, 8 extranodular regions) were systematically classified. Discordant areas were interactively analyzed in manually and rigidly registered images using a commercially available fusion tool. No side-by-side reading was performed. Results: Image fusion disclosed that the evaluation of the PET images alone led to a mislocalization in 26 of 91 focally FDG enhancing lesions. The overall sensitivities of PET, CT, and image fusion were 85, 88, and 94%, respectively; the overall specificities of PET, CT and image fusion were 98, 95 and 100%, respectively. Image fusion exhibited statistically significant higher specificity values as compared with CT. Ten definitely malignant sites were false-negative in CT, but could be detected by PET. On the other hand, twelve metastases were false-negative in PET, but could be detected by CT. These included two lesions, which had a clear correlate on the PET image when the fused images were evaluated. On the whole, registration of the PET and CT images yielded additional diagnostic information in 44% of the definitely malignant lesions. Conclusion: Retrospective image fusion of independently obtained PET and CT data is particularly valuable in exactly localizing foci of abnormal FDG uptake and improves the detection of metastases of malignant melanoma.

Attenuation correction of SPECT images based on separately performed CT

Aim: A new software approach uses separately acquired CT images for attenuation correction after retrospective fusion with the SPECT data. This study evaluates the effect of this CT-based attenuation correction on indium- 111-pentetreotide-SPECT images. Methods: Indium- 111-pentetreotide-SPECT imaging using a dual-head gamma camera e.cam (Siemens Medical Solutions, Erlangen, Germany) as well as separate spiral computed tomography (CT) was performed in 13 patients. After fusion of SPECT and CT data, the bilinear attenuation coefficients were calculated for each pixel in the CT image volume using their Hounsfield unit values and attenuation- corrected images were reconstructed iteratively (OSEM 2D). Regions of interest (ROIs) were drawn on 24 suspicious foci and background, and target to background ratios were calculated for corrected (TBAC) and uncorrected (TBNAC) images. The shortest distance from the centre of the lesion to the surface of the body (DS) was measured on the corresponding CT slice. Furthermore, ROIs were drawn over the rim and the centre of the liver. Ratios of hepatic count rates for corrected (LRAC) and uncorrected (LRNAC) images were also compared. Results: In lesions located more centrally, TBAC was up to 52% higher, whereas in peripherally located lesions, TBAC was up to 63% lower than TBNAC. The TBAC/TBNAC quotient was linearly correlated with DS. In the liver, attenuation correction resulted in a 35% increase of LRAC compared with LRNAC. Conclusions: Attenuation correction of SPECT images performed by separately acquired CT data is quick and simple. It improves the contrast between target and background for lesions located more centrally in the body and improves homogeneity of the visualisation of tracer uptake in the liver.

Anatomical accuracy of lesion localization

The aim of this study was to evaluate the anatomical accuracy and reproducibility of retrospective interactive rigid image registration (RIR) between routinely archived X-ray computer tomography (CT) and positron emission tomography performed with 18F-deoxyglucose (FDG-PET) in oncological patients. Methods: Two observers registered PET and CT data obtained in 37 patients using a commercially available image fusion tool. RIR was performed separately for the thorax and the abdomen using physiological FDG uptake in several organs as a reference. One observer performed the procedure twice (O1a and O1b), another person once (O2). For 94 malignant lesions, clearly visible in CT and PET, the signed and absolute distances between their representation on PET and CT were measured in X-, Y-, and Z-direction with reference to a coordinate system centered in the CT representation of each lesion (X-, Y-, Z-distances). Results: The mean differences of the signed and absolute distances between O1a, O1b, and O2 did not exceed 3 mm in any dimension. The absolute X-, Y-, and Z-distances ranged between 0.57 ± 0.58 cm for O1a (X-direction) and 1.12 ± 1.28 cm for O2 (Z-direction). When averaging the absolute distances measured by O1a, O1b, and O2, the percentage of lesions misregistered by less than 1.5 cm was 91 % for the X-, 88 % for the Y-, and 77 % for the Z-direction. The larger error of fusion determined for the remaining lesions was caused by non-rigid body transformations due to differences in breathing, arm position, or bowel movements between the two examinations. Mixed effects analysis of the signed and absolute X-, Y-, and Z-distances disclosed a significantly greater misalignment in the thorax than in the abdomen as well as axially than transaxially. Conclusion: The anatomical inaccuracy of RIR can be expected to be <1.5 cm for the majority of neoplastic foci. Errors of alignment are bigger in the thorax and in Z-direction, due to non-rigid body transformations caused, e.g., by breathing.

Anatomical accuracy of interactive and automated rigid registration between X-ray CT and FDG-PET

Aim: Comparison of anatomical accuracy of softwarebased interactive (IRR) and automated rigid registration (ARR) of separately acquired CT and FDG-PET data sets. Patients, methods: Independently acquired PET and helical CT data from 22 tumour patients were registered manually using the Syngo advanced Fusion VC20H tool. IRR was performed separately for the thorax and the abdomen using physiological FDG uptake in several organs as a reference. In addition, ARR was performed with the commercially available software tool Mirada 7D on all of the patients. For both methods, the distances between the representation of 53 malignant lesions on PET and CT were measured in X-, Y-, and Z-direction with reference to a common coordinate system (X-, Y-, Z-distances). Results: The percentage of lesions misregistered by less than 1.5 cm was in X-direction 91% for IRR and 89% for ARR; in Y-direction 85% and 68%; in Z-direction 72% and 51%, respectively. The average X-, Y- and Z-distances for IRR ranged from 0.58 ± 0.55 cm (X-direction) to 1.17 ± 1.66 cm (Z-direction). For ARR, the average X-, Y- and Z-distances varied between 0.66 ± 0.61 cm (X-direction) and 1.81 ± 1.37 cm (Z-direction). Mixed effects analysis of the absolute X-, Y- and Z-distances revealed a significantly better alignment for IRR compared to ARR in Z-direction (p <0.01). Lesion size and localization either in thorax or abdomen had no significant influence on the accuracy of registration. Conclusion: For the majority of malignant lesions, manual image registration with the possibility to separately align different body segments was more accurate than the automated approach. Current software for ARR does not reach the anatomical accuracy reported for PET/ CT hybrid scanners.

Effect of CT-based attenuation correction on uptake ratios in skeletal SPECT

The aim of this study was to determine the clinical relevance of compensating SPECT data for patient specific attenuation by the use of CT data simultaneously acquired with SPECT/CT when analyzing the skeletal uptake of polyphosphonates (DPD). Furthermore, the influence of misregistration between SPECT and CT data on uptake ratios was investigated. Methods: Thirty-six data sets from bone SPECTs performed on a hybrid SPECT/CT system were retrospectively analyzed. Using regions of interest (ROIs), raw counts were determined in the fifth lumbar vertebral body, its facet joints, both anterior iliacal spinae, and of the whole transversal slice. ROI measurements were performed in uncorrected (NAC) and attenuation-corrected (AC) images. Furthermore, the ROI measurements were also performed in AC scans in which SPECT and CT images had been misaligned by 1 cm in one dimension beforehand (ACX, ACY, ACZ). Results: After AC, DPD uptake ratios differed significantly from the NAC values in all regions studied ranging from 32% for the left facet joint to 39% for the vertebral body. AC using misaligned pairs of patient data sets led to a significant change of whole-slice uptake ratios whose differences ranged from 3,5 to 25%. For ACX, the average left-to-right ratio of the facet joints was by 8% and for the superior iliacal spines by 31% lower than the values determined for the matched images (p <0.05). Conclusions: AC significantly affects DPD uptake ratios. Furthermore, misalignment between SPECT and CT may introduce significant errors in quantification, potentially also affecting leftto- right ratios. Therefore, at clinical evaluation of attenuation- corrected scans special attention should be given to possible misalignments between SPECT and CT.

The interplay of autophagy and β-Catenin signaling regulates differentiation in acute myeloid leukemia

The major feature of leukemic cells is an arrest of differentiation accompanied by highly active proliferation. In many subtypes of acute myeloid leukemia, these features are mediated by the aberrant Wnt/β-Catenin pathway. In our study, we established the lectin LecB as inducer of the differentiation of the acute myeloid leukemia cell line THP-1 and used it for the investigation of the involved processes. During differentiation, functional autophagy and low β-Catenin levels were essential. Corresponding to this, a high β-Catenin level stabilized proliferation and inhibited autophagy, resulting in low differentiation ability. Initiated by LecB, β-Catenin was degraded, autophagy became active and differentiation took place within hours. Remarkably, the reduction of β-Catenin sensitized THP-1 cells to the autophagy-stimulating mTOR inhibitors. As downmodulation of E-Cadherin was sufficient to significantly reduce LecB-mediated differentiation, we propose E-Cadherin as a crucial interaction partner in this signaling pathway. Upon LecB treatment, E-Cadherin colocalized with β-Catenin and thereby prevented the induction of β-Catenin target protein expression and proliferation. That way, our study provides for the first time a link between E-Cadherin, the aberrant Wnt/β-Catenin signaling, autophagy and differentiation in acute myeloid leukemia. Importantly, LecB was a valuable tool to elucidate the underlying molecular mechanisms of acute myeloid leukemia pathogenesis and may help to identify novel therapy approaches.

[SPECT/CT - Technical aspects and optimization possibilities]

In contrast to positron emission tomography/computed tomography (PET/CT), the currently available single photon emission computed tomography/computed tomography (SPECT/CT) systems are very heterogeneous. On the side of the gamma cameras, dual-head systems are established, which are not very different from one manufacturer to the other. For the CT component, there are low dose tubes on the one side and flat detector-based cone beam CT and multislice-CT on the other. The CT image data can be used for anatomic correlation of suspicious findings as well as for attenuation correction of SPECT data. Attenuation correction enables on the one hand enhancement of SPECT image quality and on the other hand quantification of the radioactivity concentration becomes possible. Modern iterative reconstruction algorithms allow scatter correction and attenuation correction of SPECT data using the density values from CT. It still has to be shown to what extent attenuation-corrected whole body SPECT/CT studies will be able to improve the sensitivity of scintigraphy studies. As SPECT/CT primarily aims at morphologic correlation and not detection of additional lesions, an attempt should be made to balance the necessary anatomic information and the additional radiation exposure. Besides SPECT-guided CT all technical possibilities for dose reduction should be exhausted.

Effect of CT-based attenuation correction on uptake ratios in skeletal SPECT

The AIM of this study was to determine the clinical relevance of compensating SPECT data for patient specific attenuation by the use of CT data simultaneously acquired with SPECT/CT when analyzing the skeletal uptake of polyphosphonates (DPD). Furthermore, the influence of misregistration between SPECT and CT data on uptake ratios was investigated.

METHODS

Thirty-six data sets from bone SPECTs performed on a hybrid SPECT/CT system were retrospectively analyzed. Using regions of interest (ROIs), raw counts were determined in the fifth lumbar vertebral body, its facet joints, both anterior iliacal spinae, and of the whole transversal slice. ROI measurements were performed in uncorrected (NAC) and attenuation-corrected (AC) images. Furthermore, the ROI measurements were also performed in AC scans in which SPECT and CT images had been misaligned by 1 cm in one dimension beforehand (ACX, ACY, ACZ).

RESULTS

After AC, DPD uptake ratios differed significantly from the NAC values in all regions studied ranging from 32% for the left facet joint to 39% for the vertebral body. AC using misaligned pairs of patient data sets led to a significant change of whole-slice uptake ratios whose differences ranged from 3,5 to 25%. For ACX, the average left-to-right ratio of the facet joints was by 8% and for the superior iliacal spines by 31% lower than the values determined for the matched images (p < 0.05).

CONCLUSIONS

AC significantly affects DPD uptake ratios. Furthermore, misalignment between SPECT and CT may introduce significant errors in quantification, potentially also affecting left-to-right ratios. Therefore, at clinical evaluation of attenuation-corrected scans special attention should be given to possible misalignments between SPECT and CT.

Anatomical accuracy of interactive and automated rigid registration between X-ray CT and FDG-PET

AIM

Comparison of anatomical accuracy of software-based interactive (IRR) and automated rigid registration (ARR) of separately acquired CT and FDG-PET data sets.

PATIENTS, METHODS

Independently acquired PET and helical CT data from 22 tumour patients were registered manually using the Syngo advanced Fusion VC20H tool. IRR was performed separately for the thorax and the abdomen using physiological FDG uptake in several organs as a reference. In addition, ARR was performed with the commercially available software tool Mirada 7D on all of the patients. For both methods, the distances between the representation of 53 malignant lesions on PET and CT were measured in X-, Y-, and Z-direction with reference to a common coordinate system (X-, Y-, Z-distances).

RESULTS

The percentage of lesions misregistered by less than 1.5 cm was in X-direction 91% for IRR and 89% for ARR; in Y-direction 85% and 68%; in Z-direction 72% and 51%, respectively. The average X-, Y- and Z-distances for IRR ranged from 0.58 +/- 0.55 cm (X-direction) to 1.17 +/- 1.66 cm (Z-direction). For ARR, the average X-, Y- and Z-distances varied between 0.66 +/- 0.61 cm (X-direction) and 1.81 +/- 1.37 cm (Z-direction). Mixed effects analysis of the absolute X-, Y- and Z-distances revealed a significantly better alignment for IRR compared to ARR in Z-direction (p < 0.01). Lesion size and localization either in thorax or abdomen had no significant influence on the accuracy of registration.

CONCLUSION

For the majority of malignant lesions, manual image registration with the possibility to separately align different body segments was more accurate than the automated approach. Current software for ARR does not reach the anatomical accuracy reported for PET/CT hybrid scanners.

Trafficking of Shiga toxin/Shiga-like toxin-1 in human glomerular microvascular endothelial cells and human mesangial cells

This study has determined the intracellular transport route of Shiga-like toxin (Stx) and the highly related Shiga toxin in human glomerular microvascular endothelial cells (GMVECs) and mesangial cells. In addition, the effect of tumor necrosis factor-alpha (TNF-alpha), which contributes to the pathogenesis of hemolytic-uremic syndrome, was evaluated more profound. Establishing the transport route will provide better understanding of the cytotoxic effect of Stx on renal cells. For our studies, we used receptor-binding B-subunit (StxB), which is identical between Shiga toxin and Stx-1. The transport route of StxB was studied by immunofluorescence microscopy and biochemical assays that allow quantitative analysis of retrograde transport from plasma membrane to Golgi apparatus and endoplasmic reticulum (ER). In both cell types, StxB was detergent-resistant membrane associated and followed the retrograde route. TNF-alpha upregulated Gb3 expression in mesangial cells and GMVECs, without affecting the efficiency of StxB transport to the ER. In conclusion, our study shows that in human GMVECs and mesangial cells, StxB follows the retrograde route to the Golgi apparatus and the ER. TNF-alpha treatment increases the amount of cell-associated StxB, but not retrograde transport as such, making it likely that the strong TNF-alpha-induced sensitization of mesangial cells and GMVECs for the toxic action of Stx is not due to a direct effect on the intracellular trafficking of the toxin.

Antithrombin deficiency and its relationship to severe burns

Antithrombin (AT) is an important endogenous anticoagulant and exhibits marked anti-inflammatory properties. To evaluate the incidence of AT deficiency in severe burn and its correlation to the variables of the abbreviated burn severity index (ABSI), length of hospital stay (LOS) and mortality we collected data on the substitution of human plasma-derived AT concentrate in 201 consecutive patients suffering from severe burn. One hundred and eight patients (54%) developed AT deficiency during their hospitalisation and, according to our institutional practice, received substitution therapy by continuous infusion to maintain physiological plasma activity (70-120%). The mean administered dose served as a measure of AT deficiency. The percentage of patients in an AT deficient state was highest within the first 5 days after injury. It was 26% on day 1 and between 38% and 41% on days 2-5 and thereafter decreased constantly over time. A multiple regression analysis between the dependent variable mean administered dose of AT concentrate and the independent variables age, total body surface area burned (TBSA), gender, inhalation injury (INHAL), full thickness burn (FTB), LOS and mortality was performed. Age, gender and FTB showed no significant influence on the development of AT deficiency. Increasing TBSA and INHAL clearly increase the risk of developing AT deficiency (p-values 0.0001 and 0.037). The analysis also identified AT deficiency as an independent predictor of LOS and mortality (p-values 0.036 and 0.003). Development of AT deficiency is a frequent event after burn with significant correlation to TBSA and INHAL, increased mortality rates and longer hospital stays.

Retrospective interactive rigid fusion of (18)F-FDG-PET and CT. Additional diagnostic information in melanoma patients

AIM

This study investigates whether interactive rigid fusion of routine PET and CT data improves localization, detection and characterization of lesions compared to separate reading. For this purpose, routine PET and CT scans of patients with metastases from malignant melanoma were used.

PATIENTS, METHODS

In 34 patients with histologically confirmed malignant melanoma, FDG-PET and spiral CT were performed using clinical standard protocols. For all of these patients, gold standard was available. Clinical and radiological follow-up identified 82 lesions as definitely pathological. Two board-certified nuclear medicine physicians and two board-certified radiologists analyzed PET and CT images independently from each other. For each patient up to 32 anatomical regions (24 lymph node regions, 8 extranodular regions) were systematically classified. Discordant areas were interactively analyzed in manually and rigidly registered images using a commercially available fusion tool. No side-by-side reading was performed.

RESULTS

Image fusion disclosed that the evaluation of the PET images alone led to a mislocalization in 26 of 91 focally FDG enhancing lesions. The overall sensitivities of PET, CT, and image fusion were 85, 88, and 94%, respectively; the overall specificities of PET, CT and image fusion were 98, 95 and 100%, respectively. Image fusion exhibited statistically significant higher specificity values as compared with CT. Ten definitely malignant sites were false-negative in CT, but could be detected by PET. On the other hand, twelve metastases were false-negative in PET, but could be detected by CT. These included two lesions, which had a clear correlate on the PET image when the fused images were evaluated. On the whole, registration of the PET and CT images yielded additional diagnostic information in 44% of the definitely malignant lesions.

CONCLUSION

Retrospective image fusion of independently obtained PET and CT data is particularly valuable in exactly localizing foci of abnormal FDG uptake and improves the detection of metastases of malignant melanoma.

[Anatomical accuracy of lesion localization. Retrospective interactive rigid image registration between 18F-FDG-PET and X-ray CT]

The aim of this study was to evaluate the anatomical accuracy and reproducibility of retrospective interactive rigid image registration (RIR) between routinely archived X-ray computer tomography (CT) and positron emission tomography performed with 18F-deoxyglucose (FDG-PET) in oncological patients.

METHODS

Two observers registered PET and CT data obtained in 37 patients using a commercially available image fusion tool. RIR was performed separately for the thorax and the abdomen using physiological FDG uptake in several organs as a reference. One observer performed the procedure twice (O1a and O1b), another person once (O2). For 94 malignant lesions, clearly visible in CT and PET, the signed and absolute distances between their representation on PET and CT were measured in X-, Y-, and Z-direction with reference to a coordinate system centered in the CT representation of each lesion (X-, Y-, Z-distances).

RESULTS

The mean differences of the signed and absolute distances between O1a, O1b, and O2 did not exceed 3 mm in any dimension. The absolute X-, Y-, and Z-distances ranged between 0.57 +/- 0.58 cm for O1a (X-direction) and 1.12 +/- 1.28 cm for O2 (Z-direction). When averaging the absolute distances measured by O1a, O1b, and O2, the percentage of lesions misregistered by less than 1.5 cm was 91% for the X-, 88% for the Y-, and 77% for the Z-direction. The larger error of fusion determined for the remaining lesions was caused by non-rigid body transformations due to differences in breathing, arm position, or bowel movements between the two examinations. Mixed effects analysis of the signed and absolute X-, Y-, and Z-distances disclosed a significantly greater misalignment in the thorax than in the abdomen as well as axially than transaxially.

CONCLUSION

The anatomical inaccuracy of RIR can be expected to be <1.5 cm for the majority of neoplastic foci. Errors of alignment are bigger in the thorax and in Z-direction, due to non-rigid body transformations caused, e.g., by breathing.

Attenuation correction of SPECT images based on separately performed CT: Effect on the measurement of regional uptake values

AIM

A new software approach uses separately acquired CT images for attenuation correction after retrospective fusion with the SPECT data. This study evaluates the effect of this CT-based attenuation correction on indium-111-pentetreotide-SPECT images.

METHODS

Indium-111-pentetreotide-SPECT imaging using a dual-head gamma camera e.cam (Siemens Medical Solutions, Erlangen, Germany) as well as separate spiral computed tomography (CT) was performed in 13 patients. After fusion of SPECT and CT data, the bilinear attenuation coefficients were calculated for each pixel in the CT image volume using their Hounsfield unit values and attenuation-corrected images were reconstructed iteratively (OSEM 2D). Regions of interest (ROIs) were drawn on 24 suspicious foci and background, and target to background ratios were calculated for corrected (TBAC) and uncorrected (TBNAC) images. The shortest distance from the centre of the lesion to the surface of the body (DS) was measured on the corresponding CT slice. Furthermore, ROIs were drawn over the rim and the centre of the liver. Ratios of hepatic count rates for corrected (LRAC) and uncorrected (LRNAC) images were also compared.

RESULTS

In lesions located more centrally, TBAC was up to 52% higher, whereas in peripherally located lesions, TBAC was up to 63% lower than TBNAC. The TBAC/TBNAC quotient was linearly correlated with DS. In the liver, attenuation correction resulted in a 35% increase of LRAC compared with LRNAC.

CONCLUSIONS

Attenuation correction of SPECT images performed by separately acquired CT data is quick and simple. It improves the contrast between target and background for lesions located more centrally in the body and improves homogeneity of the visualisation of tracer uptake in the liver.

[CT and MRI of the petrous bone]

Diseases of the petrous bone should now be diagnosed by means of high-resolution multislice spiral computed tomography (MSCT) and/or magnetic resonance imaging (MRI). The first step in the process of diagnosis, however, must be conventional X-ray photographs (according to Schüller, Mayer, Stenvers) for screening purposes, because of the high cost of the other procedures mentioned. Because of the excellent imaging of bone structures with MSCT, this technique is especially suitable for the diagnosis both of acquired pathologies and of congenital abnormalities of the external auditory meatus, the middle ear and the mastoid, of trauma-induced pathologies of the entire petrous bone, and of osteogenic diseases. MRI is the method of choice for examination of the labyrinthine system, the interior auditory meatus and the cerebellopontine angle because it gives much the best depiction of soft tissue. Sometimes when questions remain unsolved after computed tomography (CT) examination of the middle ear MRI can be applied to complement CT, and it can yield additional information. Lesions affecting the apex of the petrous pyramid should be examined by MRI. High-resolution CT through the bone window and thin-layer MRI are both components of the presurgical diagnosis before cochlear implant (CI) surgery. For postoperative monitoring a conventional transorbital X-ray of the petrous bone is sufficient; CT is indicated only in complicated cases, and MRI is absolutely contraindicated after CI.

[Indications and diagnostic sensitivity of CT and MRI in the otorhinolaryngology field]

Of all malignant tumors, 4-5% affect the head and neck region. Computed tomography (CT) and magnetic resonance imaging (MRI) provide the means for us to determine the precise extent and depth of infiltration of space-occupying lesions, detect submucosal growth, stage lymph nodes preoperatively, and thus facilitate better preoperative planning. Thinner collimations of sections and shorter examination times are possible with modern multilayer spiral CT. Two-dimensional and three-dimensional images can be calculated from the volume specifications to assess the skull base (coronal and sagittal sections) and the midline crossover of tumors as well as staging of lymph nodes (coronal section). Examination of laryngeal and hypopharyngeal function as well as determination of tumor perfusion are also possible. Detection of tumors that do not absorb any contrast medium (approximately 15%) is more difficult with CT. In addition to providing a high degree of tissue contrast, MRI makes it possible to directly acquire images in any number of planes. In contrast to CT, metallic artefacts hardly come into play. Infiltration of the dura and the cerebrum can be depicted better with MRI than with CT. The long examination time with MRI carries the risk of movement artefacts. In the head and neck region, it is important to suppress fat in T2-weighted sequences and in T1-weighted sequences after administration of contrast media. Inflammations in the head and neck region are only exceptionally clarified with CT or MRI. It is imperative that CT be performed before functional endoscopic operations of the paranasal sinuses. Further indications for CT and MRI in cases of inflammation are the diagnosis of retrotonsillar and parapharyngeal abscesses and ensuing complications as well as the diagnosis of osteomyelitis. Since conventional sialography is contraindicated in acute inflammation in sialolithiasis, magnetic resonance sialography can be employed.

Estradiol, testosterone, dehydroepiandrosterone and androstenedione: novel derivatives and enantiomers. Interactions with rat liver microsomal cytochrome P450 and antioxidant/radical scavenger activities in vitro

Interactions of 27 steroids, among them 17 derivatives such as ethers, sulfates and amidosulfonates derived from 17 beta- and 17 alpha-estradiol, from testosterone and alpha- and beta-dihydrotesosterone and from dehydroepiandrosterone with rat liver microsomal cytochromes P450 (P450) were investigated in vitro by assessing binding to P450 and effects on P450 mediated monooxygenase functions as measured by different model reactions: ethoxyresorufin O-deethylation (EROD), ethoxycoumarin O-deethylation (ECOD) and ethylmorphine N-demethylation (EMND). With the exception of 17 alpha-estradiol-3-dimethylamidosulfonate, estrone, its -3-methylether and -3-amidosulfonate and testosterone, all other steroids displayed type I or reverse type I binding to P450. All steroids inhibited EROD activity in micromolar concentrations. An additional strong inhibition of ECOD and EMND activities was only demonstrated for the androgens and progestins. Estriol, estrone and mestranol displayed less inhibitory actions on the model reactions than estradiol. No major differences in comparison to the parent compounds were noted with the other derivatives. The only exceptions were 17 beta-(8,9-dehydro-14 alpha,15 alpha-methylene)estradiol, which displayed stronger effects than estradiol, and dehydroepiandrosterone-3-sulfate, which was less effective than dehydroepiandrosterone. Possible antioxidant properties of the steroids were examined by the stimulated lipid peroxidation (LPO), H2O2 production, and lucigenin (LC) and luminol (LM) amplified chemiluminescence (CL) using rat liver microsomes. Additionally, the influence on rat whole blood chemiluminescence (WB-CL) was assessed. All the estrogens, but not their methylethers and amidosulfonates inhibited LPO in micromolar concentrations. The effects on the other oxidase model reactions or on WB-CL were less distinct. Only ethinylestradiol and 17 beta-(8,9-dehydro-14 alpha,15 alpha-methylene)estradiol displayed a strong inhibitory action on all model reactions. With the exception of dehydroepiandrosterone-3-sulfate, which in general had only weak effects, the androgen and progestin derivatives, in contrast, strongly decreased H2O2 formation and LM- and LC-CL, but were mostly ineffective on LPO and WB-CL.

Studies on modified estrogens: towards the synthesis of novel 14,15-cyclopropa[a]estra-1,3,5(10),8-tetraenes

To improve the ratio of non-hormonal to hormonal activity, estrogens 3 and 4 were modified at various molecule positions. Isomerization of the 14 alpha,15 alpha-methylene bridge, controlled 3-methoxy group cleavage with respect to the 14 alpha,15 alpha-methylene bridge stereochemistry, reduction of the 8-double bond, and substitution of the oxyfunctionality at C-17 by a methylene and a difluoromethylene moiety were in the focus. As a result of in vivo and in vitro tests, compounds 27 and 29 were selected as potential follow-up candidates of lead 3.

Asbestos and man-made vitreous fibers as risk factors for diffuse malignant mesothelioma: results from a German hospital-based case-control study

BACKGROUND

This study examines the role of occupational factors in the development of diffuse malignant mesothelioma with special emphasis on the dose-response relationship for asbestos and on the exposure to man-made vitreous fibers (MMVFs).

METHODS

One hundred and twenty-five male cases, diagnosed by a panel of pathologists, were personally interviewed concerning their occupational and smoking history. The same number of population controls (matched for sex, age and region of residence) underwent similar interviews by trained interviewers. Odds ratios (OR) were calculated for an expert-based exposure index using conditional logistic regression.

RESULTS

Exposure to asbestos shows the expected sharp gradient with an OR of about 45 for a cumulative exposure > 1.5 fiber years (arithmetic mean 16 fiber years). A significant OR was calculated even for the lowest exposure category "> 0 - < or = 0.15 fiber years". Although the mean cumulative exposure to MMVF is roughly 10% of the exposure to asbestos, an increased OR is observed in an ever/never evaluation. This observation is heavily hampered by methodical problems. A corresponding case-control study was performed using a lung tissue fiber analysis in addition to interviews. Both interviews and the lung tissue analysis yielded similar OR levels between the reference and the maximum exposure intervals.

CONCLUSIONS

Despite a possible influence as a result of selection and information bias, our results confirm the previously reported observation of a distinct dose-response relationship even at levels of cumulative exposure below 1 fiber year. Moreover, the study confirms that asbestos is a relevant confounder for MMVF. A causal relationship between exposure to MMVF and mesothelioma could neither be detected nor excluded, as in other studies.

Antiatherogenic effects of 17 beta-estradiol and 17 alpha-estradiol and its derivative J811 in cholesterol-fed rabbits with thyroid inhibition

OBJECTIVE

The aim of this study was to investigate the antiatherogenic effects of 17 beta-estradiol and 17 alpha-estradiol and its derivative J811 (estra-1,3,5(10),8-tetraene-3, 17 alpha-diol), having a non-feminizing effect and high antioxidant potential, in male rabbits.

EXPERIMENTAL DESIGN

Male White-Russian rabbits weighing 2.1-2.6 kg were fed either a standard or a high-cholesterol (200 mg/kg) diet, with thyroid function-inhibiting thiouracil (20 mg/kg) combined with cholic acid (40 mg/kg) administered daily in sunflower oil for 3 months. During the last month of the study, estrogens were administered by gavage at a dose of 0.02 or 0.1 mg/kg.

RESULTS AND CONCLUSIONS

All three estrogens exerted remarkable antiatherosclerotic effects. Decreases in serum and aortic-wall lipid parameters and the index of atherogenicity were dependent on estrogen dose. Morphological evaluation of the aortic wall (height of plaques, size of plaque relative to aortic half-circumference) showed only weak therapeutic effects with all three estrogens. It is an open question whether the treatment period was too short to reverse the above changes. On the other hand, the data clearly suggest that 17 alpha-estradiol and J811 offer new perspectives for the prevention of atherosclerosis in men, which is similar to that found with 17 beta-estradiol in women.

Influence of sexual steroids on cell functions of PMNL in the gingival sulcus

Clinical experience confirms the influence of sexual steroids on the periodont under several clinical conditions. The mechanisms of the noticed effects are not all completely understood. In this paper, phagocytes from gingival crevice fluid of 39 patients with different forms of periodontitis and 18 healthy persons without periodontal disease were examined. Phagocytic activity was assessed in vitro. Simultaneously to phagocytic examination, 17 beta-estradiol or dienogest were added to the samples in different concentrations, in order to see whether a difference existed between phagocytosis in the presence or absence of sexual steroids. Phagocytosis was significantly reduced in patients with periodontitis. It was found that phagocytosis was raised significantly by 13% in the group with periodontal disease under the influence of 17 beta-estradiol. The administration of dienogest did not change the phagocytosis capacity significantly. In the healthy group, neither addition of 17 beta-estradiol nor addition of dienogest caused any difference.

Influence of subchronic administration of oestrone-3-O-sulphamate on oestrone sulphatase activity in liver, spleen and white blood cells of ovariectomized rats

Inhibition of oestrone sulphatase followed by oestrogen removal from tumour cells may be a new form of endocrine therapy of breast cancer in women. We investigated the inhibitory effect of the subchronic administration of oestrone-3-O-sulphamate (EMATE), a steroid sulphatase inhibitor, to ovariectomized rats, to evaluate this method for testing new nonsteroidal inhibitors. EMATE in DMSO was administered both orally and subcutaneously (s.c.) for 7 days at doses of 0.5 and 2.5 mg/kg. In addition the rats were injected s.c. with 0.5 mg oestrone sulphate/kg 26 and 2 h before decapitation under ether anaesthesia. Oestrone sulphatase activity (ESA) was measured radiometrically using [3H]oestrone sulphate as substrate for desulphuration in white blood cells, liver homogenate, microsomes and spleen homogenate. ESA in liver microsomes was found to be nearly 40 times higher than in white blood cells while in spleen ESA was nearly half of that found in liver homogenates and white blood cells. ESA can be inhibited by EMATE down to 50-1.5% of control activity depending on the dose and administration route. The inhibition was in the order, liver homogenate < spleen < liver microsomes < white blood cells, and was more pronounced after s.c. administration of the inhibitor than after oral administration. Ovariectomy was found to be not necessary for oestrone sulphatase-inhibiting studies. Two sequential s.c. injections of oestrone sulphate enhanced the enzyme activities significantly in liver and white blood cells, but not in spleen. In conclusion, white blood cells and liver microsomes of intact female rats can be used for ESA-inhibiting studies. Sulphate-conjugated oestrone can induce oestrone sulphatase in vivo in liver and white blood cells thereby enhancing oestrogen supply in the peripheral organs.

Lung cancer and exposure to man-made vitreous fibers: results from a pooled case-control study in Germany

BACKGROUND

To investigate the association between lung cancer and occupational exposure to man-made vitreous fibers (MMVF), a pooled analysis of two case-control studies was conducted in the years 1988-1994.

METHODS

The case series consisted of 3498 males who were histologically or cytologically verified primary lung cancer cases. 3541 male population controls were drawn at random from the general population and matched to cases by sex, age, and place of residence. To examine the relationship between MMVF and lung cancer we asked all study subjects who worked for at least 6 months as construction and installation workers whether they ever installed or removed insulations and what kind of insulation material they used.

RESULTS

Some 304 (8.7%) cases and 170 (4.8%) controls reported to have insulated with glass wool or mineral wool mats. Coded as ever/never exposed, the odds ratio was 1.48 (95% CI: 1.17-1.88), adjusted for smoking and asbestos. To be sure to exclude any confounding effect of asbestos, we tried to identify those cases and controls who insulated with glass wool or mineral wool mats only and never reported any asbestos exposure. For this group we calculated an odds ratio of 1.56 (95% CI: 0.92-2.65), after adjustment for smoking. An elevated risk was also estimated on the basis of an expert rating which was done for a subgroup of cases and controls. Ever exposure to MMVF (but not to asbestos) in this subgroup yielded an odds ratio of 1.30 (95% CI: 0.82-2.07).

CONCLUSIONS

Our study provides some indication for an excess risk of man-made vitreous fibers. This result also persists after adjustment for smoking and asbestos.

Positron emission tomography using [(18)F]Fluorodeoxyglucose for monitoring primary chemotherapy in breast cancer

PURPOSE

To address the role of positron emission tomography (PET) using [(18)F]fluorodeoxyglucose (FDG) to monitor primary (neoadjuvant) chemotherapy in patients with locally advanced breast cancer.

PATIENTS AND METHODS

Quantification of regional FDG uptake of the breast acquired after the first and second courses of chemotherapy was compared with the baseline scan in 22 patients with a total of 24 breast carcinomas. To evaluate the predictive value of PET imaging, histopathologic response after completion of chemotherapy classified as gross residual disease (GRD) or minimal residual disease (MRD) served as the gold standard.

RESULTS

Significant differences in tracer uptake between nonresponding tumors (GRD) and responding lesions (MRD) were observed (P <.05) as early as after the first course of chemotherapy. Tracer uptake showed little change in tumors with GRD found later in pathologic analysis but decreased sharply to the background level in most tumors with MRD. After the first course, all responders were correctly identified (sensitivity 100%, specificity 85%) by a standardized uptake value decrease below 55% of the baseline scan. At this threshold, histopathologic response could be predicted with an accuracy of 88% and 91% after the first and second courses of therapy, respectively.

CONCLUSION

This study demonstrates that in patients with advanced breast cancer undergoing primary chemotherapy, FDG-PET differentiates responders from nonresponders early in the course of therapy. This may help improve patient management by avoiding ineffective chemotherapy and supporting the decision to continue dose-intensive preoperative chemotherapy in responding patients.

Stimulation and scavestrogen-induced inhibition of reactive oxygen species generated by rat sertoli cells

The ability of Sertoli cells harvested from 18-day-old Sprague-Dawley rats to generate reactive oxygen species (ROS) occurs under unstimulated and stimulated conditions. Thus, the generation of ROS and its regulation by stimulating and inhibiting compounds was determined as a lucigenin-dependent chemiluminescence reaction. According to the data, ROS generation was influenced by different cell preparation conditions--stimulating substances such as PMA, FMLP, C5a, A23187, and scavestrogens characterized by antioxidant, radical-scavenging properties. The mechanical homogenization during cell preparation procedures leads to an increase of ROS generation. ROS generation of Sertoli cells was followed by elected substances in the following rank order of efficacy: PMA > FMLP > or = C5a > Ca-ionophore A23187. The registered inhibiting effects of the scavestrogens J811 and J861 were significant. The measured CL counts decreased at 72 and 77%, respectively, of control experiments done without scavestrogens. The generation of reactive oxygen species in Sertoli cells and especially the increase in oxygen free radicals and their effects on cellular structures of spermatids are directly involved in inducing morphological alterations. Sertoli cells play an important role in spermatogenesis. The measurements of ROS may have clinical relevance in the evaluation of infertility.

Progression of burn wound depth by systemical application of a vasoconstrictor: an experimental study with a new rabbit model

The final depth of a necrosis resulting from burn trauma is determined within 3 days. The zone of stasis has the potential for complete regeneration or there may be ischemic influences that lead to necrosis. In our model, we examined the dermal influence of vasoconstrictors with reference to the development of burn necrosis. On the backs of New Zealand white rabbits (4.0-4.5 kg) standardized lesions were made with a heated aluminum stamp at 80 degrees C, 14 s in duration. The lesions were intradermal, whereby the border zone of the coagulated tissue was found in the middle two quarters of the dermis in 100% of untreated animals after 72 h. For dermal vasoconstriction epinephrine in a dose of 0.5 microg/kg/min was used. There were two groups of seven animals each. One group received epinephrine and the dosage was dependent on the clinical state of the animal. Several cycles were administered within a 3-day period. The reduction of skin perfusion was documented by Laser-Doppler-flowmetry. After 3 days, the skin with the lesions was excised and using a hematoxylin dye, a histological examination followed. The parameter used to determine the efficacy was the thickness of the uncoagulated part of the excised dermis. Over a period of 48 h, an average of 2.3 epinephrine cycles of average of 88 min per animal in duration resulted in an average reduction of skin diffusion of 41%. The uncoagulated part of the dermis in the epinephrine group was 28.6% average; in the control group, this was 43.5%. The statistical analysis revealed significant differences with a p-value of 0.0312 (significant, when value is less than 0.05). The test results indicate that temporary reduction of skin perfusion through external administration of vasocontrictors may lead to progression of burn necrosis in our animal model. Clinically, this result indicates that for patients with burn injuries and systemic inflammatory response syndrome who have insufficient volume therapy, the administration of vasocontrictors may produce similar results in the injured area.

Radical scavenging compound J 811 inhibits hydrogen peroxide-induced death of cerebellar granule cells

Oxidative stress is considered to be an important pathophysiological condition to promote cell death in a broad variety of disorders, such as cardiovascular and neurodegenerative diseases. Scavestrogens, structurally derived from estradiol, are potent radical scavengers and inhibitors of iron-induced cell damage in vitro. In this study the potential cytoprotective effects of the so-called scavestrogen estra-1,3,5(10),8-tetraene-3,17alpha-diol, J 811, was tested using rat cerebellar granule cells (CGCs) exposed to 25 or 50 microM hydrogen peroxide (H2O2). H2O2-induced apoptotic cell death was detected by the appearance of high molecular weight DNA fragments and nuclear condensation. The addition of J 811 before or shortly after the exposure to H2O2 prevented CGC apoptosis in a dose-dependent manner. The estrogen receptor antagonist ICI 182.780 failed to prevent the protective effect of J 811, suggesting that the latter is not dependent on estrogen receptor activation. The lack of protection against apoptosis caused by colchicine suggests that J 811 is neither interfering with the activation of caspase-3, nor acting downstream of caspase-3. Therefore, the protective effect observed against H2O2 seems to be upstream caspases activation, pointing to a scavenging action of J 811. Thus the scavestrogen J 811 is a powerful antioxidant able to interfere with radical-mediated cell death and is potentially useful in diseases where reactive oxygen species are involved.

18F-FDG PET studies in patients with extratemporal and temporal epilepsy: evaluation of an observer-independent analysis

The aim of this study was to evaluate an observer-independent analysis of 18F-fluorodeoxyglucose (FDG) PET studies in patients with temporal or extratemporal epilepsy.

METHODS

Twenty-seven patients with temporal epilepsy and 22 patients with extratemporal epilepsy were included in the study. All patients with temporal epilepsy and 7 patients with extratemporal epilepsy underwent surgical treatment. In patients who showed significant postoperative improvement (temporal, n = 23; extratemporal, n = 6), the epileptogenic focus was assumed to be located in the area of surgical resection. In extratemporal epilepsy patients who did not undergo surgery, the focus localization was determined using a combination of semiology, ictal and interictal electroencephalography, [99mTc]ethyl cysteinate dimer SPECT, MRI and [11C]flumazenil PET. Visual analysis was performed by two experienced and two less experienced blinded observers using sagittal, axial and coronal images. In the automated analysis after anatomic standardization and generation of three-dimensional stereotactic surface projections (SSPs), a pixelwise comparison of 18F-FDG uptake with an age-matched reference database (n = 20) was performed, resulting in z score images. Pixels with the maximum deviation were detected, summarized and attached to one of 20 predefined surface regions of interest. For comparison with 18F-FDG PET and MR images, three-dimensional overlay images were generated.

RESULTS

In patients with temporal epilepsy, the sensitivity was comparable for visual and observer-independent analysis (three-dimensional SSP 86%, experienced observers 86%-90%, less experienced observers 77%-86%). In patients with extratemporal epilepsy, three-dimensional SSP showed a significantly higher sensitivity in detecting the epileptogenic focus (67%) than did visual analysis (experienced 33%-38%, each less experienced 19%). In temporal lobe epilepsy, there was moderate to good agreement between the localization found with three-dimensional SSP and the different observers. In patients with extratemporal epilepsy, there was a high interobserver variability and only a weak agreement between the localization found with three-dimensional SSP and the different observers. Although three-dimensional SSP detected multiple lesions more often than visual analysis, the determination of the highest deviation from the reference database allowed the identification of the epileptogenic focus with a higher accuracy than subjective criteria, especially in extratemporal epilepsy.

CONCLUSION

Three-dimensional SSP increases sensitivity and reduces observer variability of the analysis of 18F-FDG PET images in patients with extratemporal epilepsy and is, therefore, a useful tool in the evaluation of this patient group. The benefit of this analytical approach in patients with temporal epilepsy is less apparent.

Controlled prospective study of positron emission tomography using the glucose analogue [18f]fluorodeoxyglucose in the evaluation of pulmonary nodules

BACKGROUND

Positron emission tomography (PET) is a new imaging technique which, by measuring focal metabolic activities, can make a qualitative statement (benign or malignant) about a tumour. PET has been described in many studies to provide a high diagnostic accuracy for the evaluation of pulmonary coin lesions. However, these studies were not always supported by histological confirmation of the results. In a controlled prospective study, it was investigated whether the diagnostic accuracy of PET is sufficiently high to allow omission of diagnostic thoracotomy or thoracoscopy in the case of a negative finding.

METHODS

A PET scan was carried out before operation using [18F]fluorodeoxyglucose (FDG) in 50 patients with pulmonary coin lesions (diameter 30 mm or less). All of these lesions were completely removed thoracoscopically or by a formal thoracotomy and were examined histologically. Using the histology results, the diagnostic accuracy of the PET procedure with regard to a benign or malignant diagnosis was evaluated and compared with that of computed tomography (CT). Results From a total of 54 coin lesions (four of the 50 patients had two lesions) there were 31 malignant (19 primary bronchial carcinomas, 12 metastases) and 23 benign diagnoses. With the PET procedure 28 of 31 malignant and 19 of 23 benign lesions were classified correctly (sensitivity 90 per cent, specificity 83 per cent). False negatives included two bronchial carcinomas and one metastasis. CT had a sensitivity of 100 per cent and specificity of 52 per cent.

CONCLUSION

FDG PET cannot generally be considered as a replacement for diagnostic thoracoscopy or thoracotomy at the present time. However, by combining FDG PET with radiological follow-up, clinical applications may evolve in patients at low risk for a malignant tumour or at high risk for surgical complications.

Scavestrogens protect IMR 32 cells from oxidative stress-induced cell death

Oxidative stress is considered an important pathophysiological mechanism contributing to promote cell death in a broad variety of diseases including cardiovascular and neurodegenerative disorders. The so-called scavestrogens J811 and J861, structurally derived from 17alpha-estradiol, are potent radical scavengers and inhibitors of iron-induced cell damage in vitro. In this study the potential cytoprotective effects of the scavestrogens J811 and J861 against Fenton reagent-induced cell damage (50 microM FeSO4 plus 200 microM H2O2) were compared with those of 17alpha- and 17beta-estradiol. Cell viability studies using Trypan blue staining showed that estradiols and scavestrogens at concentrations ranging from 0.1 to 10 microM are able to protect IMR 32 neuroblastoma cells from Fenton-mediated death. In addition, these compounds decreased lipid peroxidation measured as thiobarbituric acid reactive substances and renormalize oxidative stress-increased intracellular glutathione levels. When given 6 h after the toxic stimulus, J811 and J861 rescued 60% of cells, whereas 17alpha- and 17beta-estradiol were ineffective. These results suggest that the scavestrogens J811 and J861 are powerful antioxidants capable of interfering with radical-mediated cell death in diseases known to be aggravated by reactive oxygen species. Such compounds may be useful in the development of novel treatments for stroke or neurodegenerative disorders.

Positron emission tomography in non-Hodgkin's lymphoma: assessment of chemotherapy with fluorodeoxyglucose

Positron emission tomography (PET) using F-18 fluorodeoxyglucose (FDG) was performed in non-Hodgkin's lymphoma (NHL), which is known to be highly responsive to chemotherapy, but also yields variable treatment results to answer the following questions: (1) What is the extent and time course of changes in FDG utilization in response to chemotherapy? (2) Are the changes of FDG uptake at early time points of chemotherapy predictive for therapy outcome? (3) Which quantitative FDG parameter provides the most sensitive measures of initial tumor response? Dynamic PET scans were performed in 11 patients at baseline and 1 and 6 weeks after initiation of chemotherapy. Based on attenuation corrected images acquired 30 to 60 minutes postinjection, standardized uptake values (SUV) were determined. Arterial input functions were estimated from vascular F-18 activity and the metabolic rates for FDG (MRFDG) were calculated using Patlak analysis. Before chemotherapy, high FDG uptake was found in all lesions (SUV[max] 13.3 +/- 4.2). Seven days after initiation of chemotherapy, tumor FDG uptake decreased 60% (SUV[max]). A further decrease of 42% was seen at day 42 resulting in a total decrease of 79% from baseline to day 42. During a follow-up of 16.0 +/- 4.2 months, six of the 11 patients continued to show complete remission. Seven days after initiation of chemotherapy, this group of patients displayed significantly lower mean MRFDG than the group of patients with relapse. At day 42, all parameters of FDG uptake showed a significant difference for both patient groups. The relative change of MRFDG from baseline to day 42, as well as from day 7 to day 42, was significantly larger as compared with SUV parameters. Standard chemotherapy of patients with NHL causes rapid decrease of tumor FDG uptake as early as 7 days after treatment, which continues to decline during therapy, indicating the sensitivity of metabolic signals to chemotherapeutic interventions. FDG uptake at 42 days after therapy was superior in prediction of long-term outcome over day 7 parameters. Dynamic data acquisition combined with Patlak analysis of FDG kinetics may provide superior information in therapy monitoring.

Scavestrogen sulfamates: correlation between estrone sulfatase inhibiting and antioxidant effects

In the present study estrone sulfatase (steryl-sulfatase; EC 3.1.6.2) and phenylsulfatase (arylsulfatase B; EC 3.1.6.1) inhibiting as well as antioxidant effects exerted by ring B,C unsaturated sulfamates of estrone (J 1025), 17 beta-estradiol (J 1054, J 1059, J 1067), and 17 alpha-estradiol (J 1051, J 1064, J 1065) were examined as compared with their parent compounds, J 994, J 995, and J 1050, using six different in vitro models: (i) estrone sulfatase activity in human placental microsomes, (ii) phenylsulfatase activity isolated from Helix pomatia, (iii) Fenton reaction driven lipid peroxidation in rat synaptosomes, (iv) Fe(II)-chelating activities, (v) formation of superoxide anion radicals, and (vi) total antioxidative activities. Ring B,C unsaturated estrogen (so-called scavestrogen) sulfamates were found to act as potent inhibitors of the following enzyme activities and generated radicals: estrone sulfatase, phenylsulfatase, lipid peroxyl, and superoxide anion. In addition, scavestrogen sulfamates were able to influence the iron redox chemistry and total antioxidative activities. These findings indicate that relatively minor modifications in the chemical structure of classical steroid sulfamates can preserve or enhance their estrone sulfatase inhibiting properties and, simultaneously, amplify their antioxidant capacity to a great extent. Taken together, our data suggest that scavestrogen sulfamates such as J 1025, J 1051, or J 1054 (17 beta-dihydroequilenin sulfamate) may serve as a very promising basis for the development of steroid-derived estrone sulfate-sulfatase inhibitors characterized by promising estrone sulfatase inhibiting activities in combination with a "good" antioxidant potency.

Novel estrogens and their radical scavenging effects, iron-chelating, and total antioxidative activities: 17 alpha-substituted analogs of delta 9(11)-dehydro-17 beta-estradiol

Antioxidant effects of N,N-dimethyl-p-toluidine, p-cresol, and p-(hydroxy)thioanisol 17 alpha-substituted analogs of 17 beta-estradiol and their delta 9(11)-dehydro homologs were investigated using four different in vitro models: rat synaptosomal lipid peroxidation induced by Fenton's reagent, Fe(II)-chelating activities, the formation of superoxide anion radicals, and total antioxidative activity. Whereas the classical estrogen 17 beta-estradiol as well as selected phenolic compounds was only moderately inhibiting iron-dependent lipid peroxidation and stimulating total antioxidative activity, besides delta 9(11)-dehydro-17 beta-estradiol (J 1213), novel estrogens such as C-17-oriented side chain analogs of 17 beta-estradiol (J 843, J 872, and J 897) and delta 9(11)-dehydro homologs (J 844, J 864, and J 898) directly altered the iron redox chemistry and diminished the formation of superoxide anion radicals generated by a xanthine/xanthine oxidase-dependent luminescence reaction to a great extent. These results suggest that definite modifications in the chemical structure of 17 beta-estradiol, e.g., the introduction of a delta 9(11)-double bond and/or p-cresol as well as p-(hydroxy)thioanisol C-17 substitution, may result in substantial changes in their antioxidant behavior. These compounds may be drug candidates for treating pathologies related to free radical formation.

Ventilation perfusion scintigraphy and lung function testing to assess metal stent efficacy

Stent implantation in malignant bronchial stenoses is a highly effective method of providing symptomatic relief by restoring bronchial patency. Whether an improvement in ventilatory conditions is paralleled by an increase in blood flow and gas exchange has not yet been determined.

METHODS

Fourteen patients with malignant, high-grade obstruction of bronchi who had metal stent implantation were investigated. Before the intervention and again 8 days afterward, both quantitative technegas ventilation and 99mTc-MAA perfusion scans (V/Q scans) and lung function tests were performed.

RESULTS

Stent implantation was successful in all patients, with a significant reduction in the degree of bronchial stenosis (pre-stent: 93% +/- 1.5%; post-stent: 16% +/- 3.5%). After stent implantation, ventilation scintigraphy revealed an improvement in tracer deposition by 65% (pre-stent: 37% +/- 8%; post-stent: 61% +/- 6%; p < 0.05) within the affected lung. A complementary increase of 71% by perfusion scintigraphy was obtained (pre-stent: 27% +/- 4%; post-stent: 46% +/- 5%; p < 0.01%). Based on scintigraphic criteria, stenting was successful in 93% (n = 13) of all patients. Lung function studies performed after the intervention showed significant improvement in vital capacity (VC, p < 0.01), forced expiratory volume in 1 sec (FEV1, p < 0.05), peak expiratory flow (PEF, p < 0.05), arterial oxygen (PaO2, p < 0.05) and carbon dioxide (PaCO2, p < 0.05) tension, and oxygen saturation (p < 0.05).

CONCLUSION

Stenting of malignant high-grade bronchial obstructions leads to an increase in bronchial patency and in activity distribution of both ventilation and perfusion scintigraphy of the affected lung, accompanied by significant improvement in lung function parameters.

Breast imaging with fluorine-18-FDG PET: quantitative image analysis

This study evaluated various quantitative criteria for analysis of breast imaging with PET using the radiolabeled glucose analog 18F-fluorodeoxyglucose (FDG).

METHODS

In a prospective study, 73 patients with abnormal mammography or palpable breast masses scheduled for biopsy were investigated with PET. A total of 97 breast tumors were evaluated by histology, including 46 benign and 51 malignant tumors. Using a whole-body PET scanner, attenuation-corrected images were acquired between 40 and 60 min after tracer injection. For Patlak analysis, dynamic data acquisition was obtained in 24 patients. To differentiate between benign and malignant breast tumors, receiver operating characteristic curves were calculated using incrementally increasing threshold values for tumor/ nontumor ratios based on average and maximum activity values per region of interest, standardized uptake values (corrected for partial volume effect, normalized to blood glucose, partial volume effect and blood glucose, using the lean body mass as well as the body surface area) and calculating the FDG influx rate (K) assessed by Patlak analysis.

RESULTS

Quantification of FDG uptake in breast tumors provided objective criteria for differentiation between benign and malignant tissue with similar diagnostic accuracy as compared with visual analysis. Applying correction for partial volume effect and normalization by blood glucose yielded the highest diagnostic accuracy.

CONCLUSIONS

These quantitative methods provided accurate evaluation of PET data for differentiating benign from malignant breast tumors. Quantitative assessment is recommended to complement visual image interpretation with the potential benefit of reduced interobserver variability.