Causes of Hypoxemia in COVID-19 Acute Respiratory Distress Syndrome: A Combined Multiple Inert Gas Elimination Technique and Dual-energy Computed Tomography Study

BACKGROUND

Despite the fervent scientific effort, a state-of-the art assessment of the different causes of hypoxemia (shunt, ventilation-perfusion mismatch, and diffusion limitation) in COVID-19 acute respiratory distress syndrome (ARDS) is currently lacking. In this study, the authors hypothesized a multifactorial genesis of hypoxemia and aimed to measure the relative contribution of each of the different mechanism and their relationship with the distribution of tissue and blood within the lung.

METHODS

In this cross-sectional study, the authors prospectively enrolled 10 patients with COVID-19 ARDS who had been intubated for less than 7 days. The multiple inert gas elimination technique (MIGET) and a dual-energy computed tomography (DECT) were performed and quantitatively analyzed for both tissue and blood volume. Variables related to the respiratory mechanics and invasive hemodynamics (PiCCO [Getinge, Sweden]) were also recorded.

RESULTS

The sample (51 ± 15 yr; Pao2/Fio2, 172 ± 86 mmHg) had a mortality of 50%. The MIGET showed a shunt of 25 ± 16% and a dead space of 53 ± 11%. Ventilation and perfusion were mismatched (LogSD, Q, 0.86 ± 0.33). Unexpectedly, evidence of diffusion limitation or postpulmonary shunting was also found. In the well aerated regions, the blood volume was in excess compared to the tissue, while the opposite happened in the atelectasis. Shunt was proportional to the blood volume of the atelectasis (R2 = 0.70, P = 0.003). V˙A/Q˙T mismatch was correlated with the blood volume of the poorly aerated tissue (R2 = 0.54, P = 0.016). The overperfusion coefficient was related to Pao2/Fio2 (R2 = 0.66, P = 0.002), excess tissue mass (R2 = 0.84, P < 0.001), and Etco2/Paco2 (R2 = 0.63, P = 0.004).

CONCLUSIONS

These data support the hypothesis of a highly multifactorial genesis of hypoxemia. Moreover, recent evidence from post-mortem studies (i.e., opening of intrapulmonary bronchopulmonary anastomosis) may explain the findings regarding the postpulmonary shunting. The hyperperfusion might be related to the disease severity.

EDITOR’S PERSPECTIVE

Enhancing PSMA-uptake with androgen deprivation therapy - a new way to detect prostate cancer metastases?

Purpose:

⁶⁸Ga-PSMA PET/CT imaging is a promising modality for the staging of recurrent prostate cancer (PCa). Current evidence suggests limited diagnostic value of the ⁶⁸Ga-PSMA PET/CT in PSA-levels ≤0.3ng/mL. Experimental data have demonstrated an increase in PSMA-expression in PCa metastases by androgen deprivation in vitro. The aim of the current study was to investigate a possible enhancing effect of PSMA with low-dose androgen deprivation in patients with BCR and low PSA-levels.

Materials and Methods:

Five patients with PCa and BCR, following radical prostatectomy, underwent ⁶⁸Ga-PSMA PET/CT. A consecutive ⁶⁸Ga-PSMA PET/CT was performed 6 to 11 days after injection of 80mg of Degarelix (Firmagon^®). We recorded PSA and testosterone serum-levels and changes of PSMA-uptake in ⁶⁸Ga-PSMA PET/CT images. Results: Median PSA prior ⁶⁸Ga-PSMA PET/CT was 0.27ng/mL. All patients had a decrease in testosterone serum levels from median 2.95μg/l to 0.16μg/l following Degarelix injection. We observed an increase in the standardized uptake value (SUV) in PSMA-positive lymphogenous and osseous lesions in two patients following androgen deprivation. In another two patients, no PSMA positive signals were detected in either the first or the second scan.

Conclusion:

Our preliminary results of this feasibility assessment indicate a possible enhancing effect of PSMA-imaging induced by low-dose ADT. Despite several limitations and the small number of patients, this could be a new approach to improve staging by ⁶⁸Ga-PSMA PET/CT in PCa patients with BCR after primary therapy. Further prospective studies with larger number of patients are needed to validate our findings.

99mTc-Besilesomab-SPECT/CT in Infectious Endocarditis: Upgrade of a Forgotten Method?

Infective endocarditis displays a serious condition with high mortality rates. Establishing a reliable diagnosis can be challenging. This study evaluates granulocyte imaging with ^99mTc-Besilesomab-SPECT/CT in order to determine the clinical value of the method and its possible redefinition through the addition of hybrid imaging. The study comprises 26 consecutive patients with suspected infectious endocarditis or prosthetic valve infection that underwent ^99mTc-Besilesomab-SPECT/CT in our facility between December 2016 and September 2018. ^99mTc-Besilesomab-SPECT/CT images were reviewed by two independent and blinded observers and results were evaluated by transesophageal echocardiography (TEE) and blood culture results as well as by pathological, bacteriological, and clinical findings. Target-to-Background-Ratios were calculated for semi-quantitative analysis. 13/26 patients were in a post-surgical stage. ^99mTc-Besilesomab-SPECT/CT was positive in 6 cases. All 6 cases were true positive confirmed by pathological or clinical findings according to the modified Duke Criteria for infective endocarditis. Remaining 19/26 cases were true negative. Target-to-Background ratios were significantly higher in patients that were visually scored positive compared to negative cases. Inter-observer agreement was very good of deciding whether a scan was positive or negative. Sensitivity of ^99mTc-Besilesomab-SPECT/CT was 86–100% and specificity was 100%. ^99mTc-Besilesomab-SPECT/CT is a useful imaging method for the diagnosis of endocarditis, especially in difficult cases with prosthetic valves or cardiac devices and inconclusive findings in echocardiography. The added value of SPECT/CT was mainly finding and localizing increased uptake at a certain valve, prosthesis, or device cable.

Immunohistochemical detection of chemokine receptor 4 expression in chronic osteomyelitis confirms specific uptake in 68Ga-Pentixafor-PET/CT

Previous findings of our group showed the chemokine receptor CXCR4 as a suitable target in PET/CT-imaging of axial bone infections, early postoperative osteomyelitis and periprosthetic infections. The aim of this study was to verify specific uptake of ⁶⁸Ga-Pentixafor in chronic osteomyelitis.

METHODS

29 consecutive patients who underwent ⁶⁸Ga-Pentixafor-PET/CT with clinically suspected osteomyelitis were evaluated retrospectively. Bone tissues of 6 patients were available and evaluated by immunohistochemical staining for CXCR4 and autoradiography with ⁶⁸Ga-Pentixafor. Staining was performed with an anti-CXCR4 antibody. In order to detect lymphocytic infiltration and CXCR4-expressing lymphocytes double immunofluorescence with an anti-CD3 and anti-CXCR4 antibody was performed.

RESULTS

⁶⁸Ga-Pentixafor-PET/ CT was true positive in 16 and true negative in 13 patients. In available bone tissue samples, immunohistochemical staining of CXCR4 expression and autoradiography with ⁶⁸Ga-Pentixafor was highly positive. Double immunofluorescence was able to detect CXCR4-expressing T-lymphocytes within all bone samples while a control sample of noninfected tibial bone was negative for CXCR4.

CONCLUSION

⁶⁸Ga-Pentixafor-PET/CT specifically shows CXCR4-expressing immune cells in chronic osteomyelitis and is therefore a suitable method for imaging chronic infection of the skeleton.Der Chemokinrezeptor CXCR4 konnte in einer Pilotstudie unserer Arbeitsgruppe als geeignete Zielstruktur zur PET/CT-Bildgebung von frühen postoperativen und periprothetischen Osteomyelitiden sowie Osteomyelitiden im Stammskelett identifiziert werden. In dieser Studie haben wir untersucht, ob ⁶⁸Ga-Pentixafor spezifisch CXCR4-exprimierende Entzündungszellen in einer chronischen Osteomyelitis darstellen kann.

METHODEN

Es erfolgte eine retrospektive Auswertung von 29 Patienten mit klinischem Verdacht einer chronischen Osteomyelitis, die mittels ⁶⁸Ga-Pentixafor-PET/CT untersucht wurden. Hiervon lagen uns in 6 Fällen Knochengewebe zur immunhistochemischen und autoradiographischen Evaluation vor. Die Immunhistochemie wurde mit einem anti-CXCR4 Antikörper durchgeführt. Des Weiteren wurden ein anti-CD3 und der anti-CXCR4-Antikörper zur Detektion CXCR4-exprimierender Lymphozyten am Ort der Entzündung mittels Doppel- Immunfluoreszenz verwendet.

ERGEBNISSE

Die ⁶⁸Ga-Pentixafor-PET/CT war bei 16 Patienten richtig positiv und bei 13 Patienten richtig negativ. Die Färbungen der verfügbaren Knochenpräparate waren sowohl in der Immunhistochemie als auch in der Autoradiographie deutlich positiv. In der Immunfluoreszenz konnten zudem CXCR4-exprimierende Lymphozyten am Ort der Entzündung in allen Proben nachgewiesen werden. Die Kontrolle eines Präparats einer nicht infizierten distalen Tibia zeigte dagegen keine CXCR4-oder CD3-Expression.

FAZIT

Mit der ⁶⁸Ga-Pentixafor-PET/CT können spezifisch CXCR4-exprimierende Lymphozyten am Ort der Entzündung nachgewiesen werden. Die ⁶⁸Ga-Pentixafor-PET/CT stellt eine geeignete Methode in der Diagnostik chronischer Osteomyeltiden dar.

Reduced radioiodine uptake at increased iodine intake and 131I-induced release of “cold” iodine stored in the thyroid

Aim: The extent of urinary iodine excretion (UIE) provides information about iodine supply and release. In the present study we investigated correlations between UIE and radioiodine uptake (RIU) as well as effects of radioiodine therapy on UIE in patients with autonomous goitre. Patients, methods: In 197 consecutive patients with thyroid autonomy, UIE was measured twice during radioiodine test (RITe) and correlated with RIU. In 98 of these patients, thyroglobulin and thyroid volume (V) were determined prior to therapy. Individual changes in urinary iodine excretion (ΔUIE) and TG (ΔTG) could be investigated four weeks (4W) and six months (6M) after radioiodine therapy. Additionally, ΔV was determined 6M after therapy. ΔUIE, ΔTG and ΔV were correlated with target dose and target volume. Results: Patients with higher iodine excretion exhibited significantly lower thyroidal radioiodine uptake values. Twofold increased UIE prior to therapy decreased radioiodine uptake by 25%. Compared with pretherapeutic values, UIE and TG were significantly increased four weeks after radioiodine therapy (p <0.001). Median values of both parameters were found to be doubled. The product of target dose and target volume was not only correlated with a decrease of thyroid volume 6M after therapy, but also with an increase of UIE and TG in the early phase after therapy. Conclusions: It was confirmed that UIE during RITe is a measure for iodine intake and can be used to investigate the competition between stable iodine and radioiodine. The increase of UIE and TG four weeks after therapeutic administration of radioiodine can be explained by disintegrated thyroid follicles. The therapy-induced iodine release may be one important cause for the development of hyperthyroidism in some patients during the first weeks after radioiodine therapy. It may contribute to the known decrease of radioiodine uptake after preapplications of 131I in various thyroid diseases.

Diagnostic 123I and 131I activities and radioiodine therapy

Aim: Urinary iodine excretion (UIE) provides information about iodine supply and release. In the present study we investigated effects of the application of different radioiodine isotopes on UIE in patients with differentiated thyroid carcinoma (DTC). Patients, methods: In 91 consecutive patients with DTC UIE, measured as iodine/creatinine ratio, was determined before and after application of 123I and 131I for diagnostic or therapeutic purposes. Additionally, remnant volume (V) was determined prior to therapy. Group A consisted of 33 patients with supposed successful ablation of DTC. These patients received 370 MBq 131I for diagnostic use and served as controls. 58 patients (group B) with remnants, relapses and metastases received 370 MBq 123I for diagnostics prior to therapy with 1.5-22.2 GBq 131I. Factors influencing individual changes in urinary iodine excretion (ΔUIE) were investigated by using non-parametric tests. Results: In group A UIE did not change significantly after application of 131I. As well, UIE remained unchanged after diagnostic application of 123I in group B. In contrast, UIE increased significantly already 24 h after therapeutic application of 131I in this group. In patients with small remnants (V < 2.5 ml) a significant but only moderate increase of UIE could be observed (average increase: 47 μg I/g crea). In patients with larger remnants, with relapses or metastases increase of UIE values was significant and more pronounced. Conclusions: It was confirmed that UIE increased significantly during radioiodine therapy in patients with DTC and radioiodine-accumulating tissue. The increase of UIE after therapeutic administration of radioiodine can be explained by the disintegrated thyroid follicles in thyroid remnants. The radioiodine-induced iodine release may be one reason for thyroid “stunning” even after application of diagnostic amounts of 131I.

High energy probe for detecting lymph node metastases with 18F-FDG in patients with head and neck cancer

Aim of this study was to validate a newly developed high energy probe (positron emission probe, PEP) optimised for localising PET tracers in vivo. Patients and methods: Physical investigations included determination of full width at half maximum (FWHM) values at a distance of 1 cm and angular resolution using different point sources. Values obtained with the new probe were compared to those of a conventional gamma probe (CGP). Additionally, PET studies were performed in 36 patients (6 women, 30 men) with proven head and neck cancer and suspected lymph node metastases (Axis, Marconi/Philips) after administering 250–320 MBq 18F-FDG. Subsequent to PET investigations 18F-FDG uptake in cervical regions was measured using the PEP. PEP investigations were carried out bilaterally in 5 lymph node (LN) levels (Robbins’ classification of the neck). Results of probe studies were correlated with visual and semiquantitative PET evaluations, US and histological findings. Results: FWHM of the new probe was 7 mm (CGP 22 mm) at 662 keV (137Cs) and angular resolution resulted in 8° (CGP 60°). In 29 out of 36 patients LN metastases were suspected due to ultrasound investigations. After neck dissection, histology confirmed LN metastases in 21 patients. Sensitivity (sens.) of US amounted to 95% and specificity to 40%. In 18/21 patients LN metastases were detected by PET (sens. 86%). PET scans failed to diagnose the LN status correctly in 6/36 patients (accuracy 83%). Employing the PEP probe in 20/21 patients LN metastases were identified (sens. 95%), and LN status was determined accurately in 29/36 patients (accuracy 81%). Tumour/ background ratios of PEP measurement and results of semiquantitative PET analyses were comparable. Conclusions: PEP measurement is a promising method for preoperative planning of the extent of neck dissection in patients with head and neck cancer and further for radioguided localising PET tracer accumulation during surgery.

How reliable is secondary risk stratification with stimulated thyroglobulin in patients with differentiated thyroid carcinoma?

Objective: Primary risk factors in patients with differentiated thyroid carcinoma (DTC) are well established. In our institution, secondary risk stratification has been performed with stimulated Thyroglobulin (sTg; TSH > 30 mIU/l) within six months after primary therapy since 2001. In this study, we evaluated the predictive value of sTg for long-term disease- free survival (DFS). Patients, methods: Data of 202 consecutive patients with DTC were analyzed retrospectively. Median follow-up time was 6.4 years (12 months to 16.2 years). Patients were staged according to Union International Contre le Cancer (UICC) criteria. Primary risk stratification was carried out according to European Thyroid Association criteria. Initially, 134 patients (66%) were classified as low-risk and 68 patients (34%) as high-risk. The influence of established risk factors and sTg on DFS was analyzed at three different time points, up to 36 months after initial therapy. Results: In total, 169 (84%) of all patients remained in complete remission after surgery followed by radioiodine-therapy. Six patients (3%) developed tumour recurrence after initial complete remission. Primary risk factors for persistent disease were male sex, follicular or oncocytic tumour, primary tumour > 4 cm in diameter, initial lymph node involvement, initial metastatic disease and microscopic or macroscopic residual tumor. sTg ≤ 0.3 ng/ml measured within six months after initial therapy was a highly significant predictor (p ≤ 0.001) for lasting DFS, 99% of patients with sTg ≤ 0.3 ng/ml were in complete remission 36 months after initial therapy. Conclusions: A stimulated Tg ≤ 0.3 ng/ml within six months after initial therapy is a reliable predictor for long-term disease- free survival independent of primary risk stratification.

68Ga-Pentixafor PET/CT Imaging of Chemokine Receptor CXCR4 in Chronic Infection of the Bone: First Insights

Because of its role in infection and inflammatory processes, the chemokine receptor CXCR4 might be a potent target in imaging of infectious and inflammatory diseases. The aim of this pilot study was to determine whether the CXCR4 ligand ⁶⁸Ga-pentixafor is suitable for imaging chronic infection of the bone. Methods: The study comprised 14 patients with suspected infection of the skeleton who underwent ⁶⁸Ga-pentixafor PET/CT between April 2015 and February 2017 in our facility. ⁶⁸Ga-pentixafor PET/CT results were retrospectively evaluated against a histologic, bacteriologic, and clinical standard. The results were also compared with available bone scintigraphy, white blood cell scintigraphy, and ¹⁸F-FDG PET/CT results. Results:⁶⁸Ga-pentixafor PET/CT was positive in 9 of 14 patients. Diagnoses included osteitis or osteomyelitis of peripheral bone, osteomyelitis of the maxilla, and infected endoprostheses. Target-to-background ratios were 5.1-15 (mean, 8.7). Eight of 9 cases were true-positive as confirmed by pathology, bacteriology, or clinical observation. All negative cases were confirmed as true-negative by other imaging modalities and follow-up. Conclusion: Imaging of CXCR4 expression with ⁶⁸Ga-pentixafor PET/CT appears suitable for diagnosing chronic infection of the skeleton. The findings of this study reveal a possible diagnostic gain in suspected chronic infections that are difficult to diagnose by other imaging modalities.

18F-FDG-PET/CT in unexplained elevated inflammatory markers. Joining entities

The diagnostic strategy in patients with fever or inflammation of unknown origin remains a major clinical challenge. The aim of this study was to evaluate the role of ¹⁸F-FDG-PET/CT in patients with unexplained elevated C-reactive protein with or without fever. Contribution of ¹⁸F-FDG-PET/CT to the final diagnosis was evaluated. In addition we determined whether a differentiation between patients with or without fever is clinically reasonable.

PATIENTS, METHODS

We retrospectively analysed 72 consecutive patients with unexplained elevated C-reactive protein levels (above 8mg/l) that underwent ¹⁸F-FDG-PET/CT in our facility between 10/2009 and 11/2012. ¹⁸F-FDG-PET/CT was considered a so-called diagnostic scan when results decisively led to a final diagnosis and adequate therapy with a response of symptoms was initiated due to the PET/CT result.

RESULTS

In 60/72 patients (83%) a final diagnosis was established. Diagnoses included infections (58%), non-infectious inflammatory diseases (29%) and malignancies (8%). ¹⁸F-FDG-PET/CT was true positive in 47 cases (65%) and the diagnostic scan in 29 patients (40%). Sensitivity of ¹⁸F-FDG-PET/CT was 81% and specificity was 86%. Diagnostics, final diagnoses, ¹⁸F-FDG-PET/CT results, SUVmax, C-reactive protein levels and the diagnostic scan did not differ significantly between patients with fever and patients without fever.

CONCLUSION

¹⁸F-FDG-PET/CT is a useful method in the diagnostic workup of patients with inflammation of unknown origin. In our series there was no significant difference between patients with or without fever. Regarding ¹⁸F-FDG-PET/CT-imaging inflammation of unknown origin and unexplained fever can be joined to one entity.

See the unseen: Mesorectal lymph node metastases in prostate cancer

BACKGROUND

Our study is the first evaluation of nodal metastatic prostate cancer (PCa) to mesorectal lymph nodes (MLN) detected by (68) Ga-PSMA-PET/CT.

METHODS

We retrospectively analyzed 76 consecutive PCa patients who underwent (68) Ga-PSMA-PET/CT: 61 PCa patients with biochemical recurrence (BCR) after curative treatment and 15 high-risk PCa before primary therapy. We assessed PET-positive MLN, which are indicative for PCa.

RESULTS

We detected PET-positive lesions for PCa in (68) Ga-PSMA-PET/CT in 66 of 76 (87%) patients. Nodal disease was imaged in 47 of 66 (71%) patients. Indicative mesorectal nodal lesions for PCa were detected in 12 of 76 (15.8%) patients. The median number of PET-positive MLN was one per patient. Seven of twelve patients had recurrent PCa after radical prostatectomy with a median PSA value of 1.84 ng/ml (range 0.31-13). Five of twelve patients had untreated first diagnosed high-risk PCa with median PSA value of 90 ng/ml (range 4.6-93) at PET/CT, respectively. For all PET positive MLN a morphological correlate was found in CT (shortest diameter median 4 mm [range 4-21]; longest diameter median 7.5 mm [range 5-25]). After PET/CT, four patients with recurrent PCa received hormonal therapy, one patient was treated with directed radiation therapy of MLN, one patient received chemotherapy, and one patient was treated with pelvic lymph node dissection. Three high-risk PCa patients received hormonal therapy, and two patients were treated with adjuvant hormonal therapy after radical prostatectomy.

CONCLUSIONS

Detection and exact location of nodal metastasis for PCa is crucial for the choice of treatment and the patient's prognosis. (68) Ga-PSMA-PET/CT seems to improve the detection of nodal metastasis in PCa, especially concerning mesorectal lymph nodes.

Pelvic lymph node dissection for nodal oligometastatic prostate cancer detected by 68Ga-PSMA-positron emission tomography/computerized tomography

BACKGROUND

The first evaluation of pelvic extended lymph node dissection (pLND) in oligometastatic prostate cancer (PCa) detected by (68)Ga-PSMA PET/CT.

METHODS

Retrospective analysis of 35 PCa patients underwent (68)Ga-PSMA PET/CT affected by biochemical recurrence (BCR) after curative treatment (n = 23) or before primary therapy of high-risk PCa (n = 12). We performed pLND associated with pathologic imaging in 17 men with nodal oligometastatic PCa.

RESULTS

Indicative lesions for PCa in PET/CT were detected in 91.4% (32 of 35) of patients. Nodal, bone, visceral (pulmonary), and within the prostate suspected disease were detected in 72% (23 of 32), 16% (5 of 32), 6% (2 of 32), and 47% (15 of 32) of patients, respectively. Median serum PSA in patients with pathological radiotracer uptake in recurrent and high-risk PCa patients was 2.9 ng/ml (range 0.18-30) and 19.5 ng/ml (range 6-90), respectively. The median number of removed lymph nodes with pLND in recurrent and high-risk PCa was 10 (range 4-17) and 12 (range 8-29) per patient and the median number of positive lymph nodes was 1 (range 1-2) and 3 (2-3) per patient, respectively. In total, two false positive and one false-negative lymph node were found. Diagnostic accuracies per nodal lesion in total of 213 removed nodes: sensitivity, 94%; specificity, 99%; positive predictive value (PPV), 89%, and negative predictive value (NPV), 99.5%. After pLND, 53% (9 of 17) of patients received androgen deprivation therapy and/or radiation therapy and hormonal therapy, while 47% (8 of 17) of patients remained free of any post-surgery therapy. Follow-up PSA remained less than 0.2 ng/ml in 82% (14 of 17) of patients. After pLND, immediate BCR (PSA never measured less than 0.2 ng/ml) in 18% (3 of 17) of patients was recorded.

CONCLUSIONS

This represents the first study of pLND in the setting of nodal oligometastatic PCa detected by (68)Ga-PSMA PET/CT. The use of (68)Ga-PSMA PET/CT could be to improve the accuracy for the detection of nodal micrometastases. These promising findings need validation in larger studies.

Biphasic ⁶⁸Ga-PSMA-HBED-CC-PET/CT in patients with recurrent and high-risk prostate carcinoma

PURPOSE

Binding of (68)Ga-PSMA-HBED-CC ((68)Ga-PSMA) at prostate cancer (PC) cells increases over time. A biphasic protocol may help separating benign from tumor lesions. The aim of this study was the retrospective evaluation of a diagnostic incremental value of a dual-time point (biphasic) (68)Ga-PSMA-PET/CT in patients with prostate cancer.

METHODS

Retrospective analysis of 35 consecutive patients (49-78 years, median 71) with newly diagnosed PC (12/35) or recurrence of PC (23/35). PET/CT (Gemini TF16, Philips) was acquired 1 h and 3 h p. i. of 140-392 MBq (300 MBq median) (68)Ga-PSMA, followed by a diagnostic contrast CT. PET findings were correlated with histology or unequivocal CT findings. Semiquantitative PET data (SUVmax, SUV mean) were acquired and target-to-background-ratios (T/B-ratio) were calculated for benign and malign lesions for both time points. Size of lymph nodes (LN) on diagnostic CT was recorded. Statistical analysis was performed for assessment of significant changes of semiquantitative PET-parameters over time and for correlation of size and uptake of lymph nodes.

RESULTS

One hundred and four lesions were evaluated. Sixty lesions were referenced by histology or unequivocal CT findings, including eight (13.3 %) histopathologically benign lymph nodes, 12 (20 %) histopathologically lymph node metastases, 12 (20 %) primary tumors, three (5 %) local recurrences, and 25 (41.7 %) bone metastases. Forty-four lesions were axillary LN with normal CT-appearance. Benign lesions had significantly lower SUVmax and T/B-ratios compared with malignant findings. Malign lesions showed a significant increase of both parameters over time compared to benign findings. There was no correlation between LN size and SUVmax. The sensitivity, specificity, the positive predictive value and negative predictive value of PET/CT regarding pelvic LN was 94 %, 99 %, 89 %, and 99.5 %, respectively.

CONCLUSIONS

In contrast to benign tissues, the uptake of proven tumor lesions increases on (68)Ga-PSMA-PET/CT over time. A biphasic PET-study may lead to a better detection of tumor lesions in unequivocal findings.

Radioprotective effect of lidocaine on neurotransmitter agonist-induced secretion in irradiated salivary glands

Background

Previously we verified the radioprotective effect of lidocaine on the function and ultrastructure of salivary glands in rabbits. However, the underlying mechanism of lidocaine's radioprotective effect is unknown. We hypothesized that lidocaine, as a membrane stabilization agent, has a protective effect on intracellular neuroreceptor-mediated signaling and hence can help preserve the secretory function of salivary glands during radiotherapy.

Methods and Materials

Rabbits were irradiated with or without pretreatment with lidocaine before receiving fractionated radiation to a total dose of 35 Gy. Sialoscintigraphy and saliva total protein assay were performed before radiation and 1 week after the last radiation fraction. Isolated salivary gland acini were stimulated with either carbachol or adrenaline. Ca²⁺ influx in response to the stimulation with these agonists was measured using laser scanning confocal microscopy.

Results

The uptake of activity and the excretion fraction of the parotid glands were significantly reduced after radiation, but lidocaine had a protective effect. Saliva total protein concentration was not altered after radiation. For isolated acini, Ca²⁺ influx in response to stimulation with carbachol, but not adrenaline, was impaired after irradiation; lidocaine pretreatment attenuated this effect.

Conclusions

Lidocaine has a radioprotective effect on the capacity of muscarinic agonist-induced water secretion in irradiated salivary glands.

Patients with autoimmune thyroiditis. Prevalence of benign lymphadenopathy

The prevalence of cervical lymphadenopathy in autoimmune thyroiditis (AIT) patients is actually unknown. The aim of the study was the detailed retrospective evaluation of 6 index-patients with lymphadenopathy in Robbins level VI and a prospective study with high resolution ultrasound of lymphadenopathy in AIT patients compared with controls in all compartments of the neck, accessible to sonographic evaluation.

PATIENTS, METHODS

The retrospective study comprises six patients with AIT, evaluated for enlarged Robbins level VI-LN. We report the findings of fine-needle aspiration Cytology, clonal analysis, histology, and serological testing. The prospective study evaluated the prevalence of lymphadenopathy in 49 consecutive patients with AIT (group 1) and 49 consecutive patients with normal thyroids or nontoxic goiter (group 2).

RESULTS

In the retrospective study, cytology of paratracheal LN revealed reactive lymphoid hyperplasia in 5/6 of the cases and a centroblastic lymphoma in one patient. The presence of monoclonal lymphatic cells was excluded in 5/6 patients and proven in 1/6 patients. Actual viral-infections were ruled out. In the prospective study AIT-patients showed significantly more enlarged LN in Robbins level II-IV and VI compared to controls. We found no correlation between lymphadenopathy, age, thyroid volume and nodularity, or autoantibody levels. During follow-up in 34 group 1-patients, lymphadenopathy remained stable in 28 patients, and decreased in 6 patients.

CONCLUSION

Lymphadenopathy in Robbins level II-IV and VI is common in AIT-patients and most probably related to the autoimmune process.

Visualizing dopamine transporter integrity with iodine-123-FP-CIT SPECT in combination with high resolution MRI in the brain of the common marmoset monkey

Considerable progress has been made in small animal single photon emission computed tomography (SPECT) imaging in the field of Parkinson's disease. In preclinical research, there is an increasing demand for in vivo imaging techniques to apply to animal models. Here, we report the first protocol for dopamine transporter (DAT) SPECT in common marmosets using the radioligand ¹²³I-N-ω-fluoropropyl-2β-carbomethoxy-3β-{4-iodophenyl}nortropane (¹²³I-FP-CIT). Serial SPECT images were obtained on an upgraded clinical scanner to determine the distribution kinetics of ¹²³I-FP-CIT in the marmoset brain. After intravenous injection of approximately 60 MBq of the radiotracer ¹²³I-FP-CIT, stable and specific striatal uptake was observed for at least 4h. Analysis of plasma samples showed rapid disappearance of the radiotracer from blood plasma within a few minutes after application, with activity declining to 4.1% of the administered activity. Structural magnetic resonance imaging (MRI) at 400 μm resolution provided the details of the underlying anatomy. In a marmoset model of Parkinson's disease, which was generated by unilateral injections of 6-hydroxydopamine (6-OHDA) into the nigro-striatal projection pathway, complete loss of striatal DAT binding in combination with behavioral deficits was observed. The presented study demonstrates that ¹²³I-FP-CIT SPECT is a suitable tool to investigate DAT integrity in preclinical studies on common marmosets.

68Ga-markierte Peptide für klinische Studien

The AMG implies far-reaching implications for the synthesis of new radiopharmaceuticals for clinical trials. Aim, methods: As a part of the DFG-funded Clinical Research Group (KFO 179) a project designated „Immuno-PET for assessment of early response to radiochemotherapy of advanced rectal cancer“ was initiated. This trial is focused on a trivalent bispecific humanized monoclonal antibody, and a 68Ga-labeled peptide. Following the new regulatory framework we established a GMPcompliant cleanroom laboratory and applied for a manufacturing permission. Results: During the project constructural, personnel and organizational conditions for a successful application were established, including a quality management system. A GMP-conform cleanroom laboratory class C was constructed, equipped with a two-chamber lock. The actual manufacturing is performed in a closed system with subsequent sterile filtration. The manufacturing processes have been automatised and validated as well as the necessary quality controls. The manufacturing permission was granted after an official inspection. Conclusions: The new German Drug Act is considered as a break in the production practice of nuclear medicine. The early involvement and communication with the authorities avoids time-consuming and costly planning errors. It is much to be hoped that the new legal situation in Germany will not cause serious impairments in the realization of clinical trials in German nuclear medicine.

Novel Carcinoembryonic-Antigen-(CEA)-Specific Pretargeting System to Assess Tumor Cell Viability after Irradiation of Colorectal Cancer Cells

PURPOSE

To date, no valid imaging modality exists for early response prediction to neoadjuvant radiochemotherapy in carcinoembryonic-antigen-(CEA)-expressing rectal cancers (UICC stages II and III). It is hypothesized that the uptake of an anti-CEA antibody is directly related to the number of viable tumor cells and may be quantified by immuno-positron emission tomography (immuno-PET). Therefore, we evaluated a novel pretargeting system using TF2, a humanized bispecific trivalent monoclonal antibody (mAb), directed against CEA and the IMP-288-peptide, a hapten for binding radiometals for imaging. Uptake and kinetics of the pretargeting system were investigated in vitro prior to and after irradiation.

METHODS

TF2 was labeled with ¹³¹I and IMP-288 with ¹¹¹InCl₃. The colorectal cancer cell lines HT29, SW480, and T84 with known varying CEA expression were incubated (≤ 72 hours) with ¹³¹I-TF2 or the TF2-¹¹¹In-IMP-288 pretargeting system. Parallel cultures were irradiated with 2-10 Gy high-energy photons. Tracer uptake, proliferation, apoptosis, and CEA-RNA expression of cancer cells were investigated.

RESULTS

The uptake of tracers was dependent on CEA expression and cell count of the cell lines (uptake/10⁶ cells: 0.3% in HT29, 1.5% in SW480, and 14% in T84, p < 0.001). The TF2-¹¹¹In-IMP-288 pretargeting system showed a higher uptake after 4 and 72 hours compared to (131)I-TF2 in parallel cultures. Only in one cell line (SW480) an increased apoptosis after irradiation could be detected. Irradiation increased dose dependently both the specific uptake of ¹³¹I-TF2 and of the TF2-¹¹¹In-IMP-288 system (4-fold in HT29 and T84 after 10 Gy (72 hours), p < 0.001). These results were CEA-mRNA independent.

CONCLUSION

This novel pretargeting system allows the quantitative analysis of CEA-expressing colorectal cancer cells and represents a promising tool for evaluation of tumor cell viability after irradiation.

Targeting NCA-95 and other granulocyte antigens and receptors with radiolabeled monoclonal antibodies (Mabs)

During the last decade considerable effort has been made in the research for in vivo techniques of labeling neutrophils with peptides, labeled cytokines and (99m)Tc-labeled antigranulocyte monoclonal antibodies (AG-Mabs). In general the advantage of in vivo labeling is the simplicity of this approach compared with in vivo techniques. Three of these AG-Mabs have been evaluated in clinical studies: Besilesomab (Scintimun®), Sulesomab (Leucoscan®) and Fanolesomab (Leu-Tech®). White blood cells (WBCs) radiolabeled with AG-Mabs do not show the same behaviour as in vivo labeled white blood cells. Especially (99m)Tc-Sulesomab and (99m)Tc-Besilesomab image infectious foci mainly by non-specific extravasation with secondary binding to postmigratory leukocytes already present at the site of infection.

Radiolabeled cetuximab plus whole-brain irradiation (WBI) for the treatment of brain metastases from non-small cell lung cancer (NSCLC)

BACKGROUND AND PURPOSE

The addition of systemic drugs to whole-brain irradiation has not improved the survival of patients with multiple brain metastases, most likely because the agents did not readily cross the blood-brain barrier (BBB). Radiolabeling of cetuximab was performed to investigate whether this antibody crosses the BBB.

CASE REPORT

A patient with multiple brain lesions from non-small cell lung cancer was investigated. The largest metastasis (40 x 33 x 27 mm) was selected the reference lesion. On day 1, 200 mg/m(2) cetuximab (0.25% hot and 99.75% cold antibody) were given. On day 3, 200 mg/m(2) cetuximab (cold antibody) were given. Weekly doses of 250 mg/m(2) cetuximab were administered for 3 months.

RESULTS

The reference lesion showed enhancement of radiolabeled cetuximab ((123)I-Erbi) on scintigraphy; (123)I-Erbi crossed the BBB and accumulated in the lesion. The reference lesion measured 31 x 22 x 21 mm at 4 months. Enhancement of contrast medium was less pronounced.

CONCLUSION

This is the first demonstration of cetuximab crossing the BBB and accumulating in brain metastasis.

New approach for the synthesis of [18F]fluoroethyltyrosine for cancer imaging: simple, fast, and high yielding automated synthesis

O-(2-[(18)F]fluoroethyl)-L-tyrosine ([(18)F]FET) is one of the first (18)F-labeled amino acids for imaging amino acid metabolism in tumors. This tracer overcomes the disadvantages of [(18)F]fluorodeoxyglucose, [(18)F]FDG, and [(11)C]methionine, [(11)C]MET. Nevertheless, the various synthetic methods providing (18)F[FET] exhibit a big disadvantage concerning the necessity of two purification steps during the synthesis including HPLC purification, which causes difficulties in the automation, moderate yields, and long synthesis times >60 min. A new approach for the synthesis of [(18)F]FET is developed starting from 2-bromoethyl triflate as precursor. After optimization of the synthesis parameters including the distillation step of [(18)F]-FCH(2)CH(2)Br combined with the final purification of [(18)F]FET using a simple solid phase extraction instead of an HPLC run the synthesis [(18)F]FET could be significantly simplified, shortened, and improved. The radiochemical yield (RCY) was about 45% (not decay corrected and calculated relative to [(18)F]F(-) activity that was delivered from the cyclotron). Synthesis time was only 35 min from the end of bombardment (EOB) and the radiochemical purity was >99% at the end of synthesis (EOS). Thus, this simplified synthesis for [(18)F]FET offers a very good option for routine clinical use.

FDG-PET in patients with fever of unknown origin: the importance of diagnosing large vessel vasculitis

This review analyzes the impact of 2-[(18)F]fluoro-2-deoxy-D-glucose (FDG)-positron emission tomography (PET) in the diagnostic work-up of classic fever of unknown origin (FUO) according to the criteria first proposed by Petersorf in 1961 and later modified by Durack et al. in 1991. Algorithms currently used in this diagnostic process are not strictly evidence based up to now. FDG accumulates in malignant tissues, but also in inflammatory cells by the overexpression of facultative glucose transporter-isotypes (mainly GLUT-1 and GLUT-3) and by an overproduction of glycolytic enzymes. Therefore, this technique covers a broad spectrum of possible etiologies for FUO. Once imaged, these lesions can be further investigated by other (e.g. invasive) and more specific methods. Until now, four prospective studies using FDG-PET in patients with classic FUO, encompassing 167 patients in total are published. Three retrospective studies with 125 patients are also available. These studies are discussed and weighted according to the control of selection-bias that was performed. An interstudy-bias may also be present resulting from a considerable variability in causes of FUO. A low number of diagnostic scans in a study may sometimes be related to a high rate of fevers caused by miscellaneous disorders or to a high rate of undiagnosed patients. In these disease categories, focal pathologies that can be imaged with FDG-PET, are rare. A high number of diagnostic scans is always related to a high prevalence of patients with medium- and large-vessel vasculitis. Available data indicate that FDG-PET has the potential to play an important role as a second line procedure in the management of about 1/3 of patients with classic FUO. It is expected that hybrid imaging (PET/computed tomography [CT]; PET/magnetic resonance imaging [MRI]) will improve the diagnostic impact of FDG-PET further, but prospective data about the value of this methods are currently not available. The question as to how these new techniques can be implemented into an evidence based diagnostic algorithm, can only be resolved within a multidisciplinary setting, avoiding both selection- and interstudy-bias whenever possible.

Kinetics and organ distribution of allogeneic natural killer lymphocytes transfused into patients suffering from renal cell carcinoma

The transfusion of natural killer (NK) lymphocytes into patients suffering from malignant diseases is an approach of current interest in the field of immunotherapy. Little is known about the organ distribution, survival, and clearance of donor immune effector cells in cellular therapy, and no reports exist on these important parameters considering NK cells in particular or any other type of allogeneic lymphocytes in humans. In the context of a clinical Phase I/II study we examined the distribution of transfused allogeneic NK cells in patients suffering from renal cell carcinoma. The NK cells were ex vivo cultivated and activated before transfusion. To assess the circulation of the transfused cells in the peripheral blood, we used a nested PCR technique to detect HLA DRB1 alleles of the NK cell donors. Post-transfusion, all patients showed evidence of circulating donor cells for up to 3 days. After 7 days, all donor cells were cleared from the blood to undetectable levels. To assess organ distribution, (111)In-labeled NK cells were injected and monitored by whole-body scintiscans. A distribution to the whole body, with preference for liver, spleen, and bone marrow, was observed after a short initial uptake in the lungs. No activity was observed in lymphatic nodes. A total of 2/4 evaluable metastases showed a clear accumulation of transfused NK cells. The half-life corrected activity in all body compartments remained almost constant over the 6-day observation period in concordance with the absence of any excretion of radioactivity. This may indicate an extended survival of the transfused cells, despite their foreign nature, in the host organism.

Performance comparison of two dual-head coincidence cameras of the first and latest generation

This study compares the performance and image quality of two gamma camera based PET systems of the first and latest generation. We investigated two dual head coincidence gamma cameras (PRISM 2000XP and AXIS, manufactured in 1997 and 2001 by Picker/Philips) predominantly in accordance with the NEMA NU2-1994 and NU2-2001 protocols. All performance parameters except for spatial resolution and image quality were determined after measuring a standard cylinder over several half-life periods. Scatter and random fractions were evaluated with the sinogram technique. In order to determine spatial resolution and image quality we used phantoms as described in the NEMA NU2-2001 protocol. The efficiency of the new system was found to be increased. True count rate at activity levels used in clinical conditions is improved and scatter fraction is decreased substantially. Accordingly, improved spatial resolution and image quality were observed with the new system. Altogether, the AXIS represents a further approach to the performance of dedicated positron emission tomographs.

High energy probe for detecting lymph node metastases with 18F-FDG in patients with head and neck cancer

AIM

of this study was to validate a newly developed high energy probe (positron emission probe, PEP) optimised for localising PET tracers in vivo.

PATIENTS AND METHODS

Physical investigations included determination of full width at half maximum (FWHM) values at a distance of 1 cm and angular resolution using different point sources. Values obtained with the new probe were compared to those of a conventional gamma probe (CGP). Additionally, PET studies were performed in 36 patients (6 women, 30 men) with proven head and neck cancer and suspected lymph node metastases (Axis, Marconi/Philips) after administering 250-320 MBq (18)F-FDG. Subsequent to PET investigations (18)F-FDG uptake in cervical regions was measured using the PEP. PEP investigations were carried out bilaterally in 5 lymph node (LN) levels (Robbins' classification of the neck). Results of probe studies were correlated with visual and semiquantitative PET evaluations, US and histological findings.

RESULTS

FWHM of the new probe was 7 mm (CGP 22 mm) at 662 keV ((137)Cs) and angular resolution resulted in 8 degrees (CGP 60 degrees ). In 29 out of 36 patients LN metastases were suspected due to ultrasound investigations. After neck dissection, histology confirmed LN metastases in 21 patients. Sensitivity (sens.) of US amounted to 95% and specificity to 40%. In 18/21 patients LN metastases were detected by PET (sens. 86%). PET scans failed to diagnose the LN status correctly in 6/36 patients (accuracy 83%). Employing the PEP probe in 20/21 patients LN metastases were identified (sens. 95%), and LN status was determined accurately in 29/36 patients (accuracy 81%). Tumour/background ratios of PEP measurement and results of semiquantitative PET analyses were comparable.

CONCLUSIONS

PEP measurement is a promising method for preoperative planning of the extent of neck dissection in patients with head and neck cancer and further for radioguided localising PET tracer accumulation during surgery.

Increased Radioiodine Uptake of Thyroid Cell Cultures after External Irradiation

BACKGROUND

Radioiodine uptake (RIU) is one of the main prognostic factors for curative results of radioiodine therapy in patients with differentiated thyroid cancer. Some days after application of (131)I, the uptake of a subsequent administration of radioiodine was found to be reduced. In contrast, early after irradiation with high-energy photons glucose and amino acid uptake were observed to be increased. Effects of external irradiation on RIU of thyrocytes using high-energy photons have not been investigated so far.

MATERIAL AND METHODS

Two different cell lines (FRTL-5 and ML-1 cells) derived from thyroid tissue were studied in vitro. Cell lines were either incubated with (131)I only (controls) or additionally irradiated with single doses of 6 or 10 Gy of high-energy photons using a linear accelerator. Cell number and RIU were determined 24-96 h after (131)I application. RIU measurements were repeated after application of sodium perchlorate in excess to investigate specificity of the uptake. Statistical analyses were performed using non-parametric tests.

RESULTS

Incubation with radioiodine as well as irradiation with high-energy photons slowed down proliferation in investigated cell lines significantly. Irradiation with solely (131)I resulted in stable or slightly decreased iodide uptake. Compared to those cells, the RIU increased significantly in externally irradiated cells, i. e., additional irradiation with 10 Gy resulted in an almost threefold increase of RIU in FRTL-5 after 72 h. The increase of RIU after irradiation was dose-dependent in both cell lines and could be blocked by perchlorate excess.

CONCLUSION

It could be demonstrated that external irradiation increases RIU in thyroid cell cultures early after irradiation. The increase was dose-dependent and specific, as it could be blocked by perchlorate. This effect appears to be similar to the increase of other actively transported substances after irradiation with high-energy photons. Therefore, the results of this study may contribute to the knowledge of a generalized irradiation-induced mechanism which causes the activation of different cellular transporters. The clinical impact of these findings on combined therapy concepts has to be investigated in further experiments.

[Reduced radioiodine uptake at increased iodine intake and 131I-induced release of "cold" iodine stored in the thyroid]

AIM

The extent of urinary iodine excretion (UIE) provides information about iodine supply and release. In the present study we investigated correlations between UIE and radioiodine uptake (RIU) as well as effects of radioiodine therapy on UIE in patients with autonomous goitre.

PATIENTS, METHODS

In 197 consecutive patients with thyroid autonomy, UIE was measured twice during radioiodine test (RITe) and correlated with RIU. In 98 of these patients, thyroglobulin and thyroid volume (V) were determined prior to therapy. Individual changes in urinary iodine excretion (DeltaUIE) and TG (DeltaTG) could be investigated four weeks (4W) and six months (6M) after radioiodine therapy. Additionally, DeltaV was determined 6M after therapy. DeltaUIE, DeltaTG and DeltaV were correlated with target dose and target volume.

RESULTS

Patients with higher iodine excretion exhibited significantly lower thyroidal radioiodine uptake values. Twofold increased UIE prior to therapy decreased radioiodine uptake by 25%. Compared with pretherapeutic values, UIE and TG were significantly increased four weeks after radioiodine therapy (p < 0.001). Median values of both parameters were found to be doubled. The product of target dose and target volume was not only correlated with a decrease of thyroid volume 6M after therapy, but also with an increase of UIE and TG in the early phase after therapy.

CONCLUSIONS

It was confirmed that UIE during RITe is a measure for iodine intake and can be used to investigate the competition between stable iodine and radioiodine. The increase of UIE and TG four weeks after therapeutic administration of radioiodine can be explained by disintegrated thyroid follicles. The therapy-induced iodine release may be one important cause for the development of hyperthyroidism in some patients during the first weeks after radioiodine therapy. It may contribute to the known decrease of radioiodine uptake after preapplications of 131I in various thyroid diseases.

Diagnostic 123I and 131I activities and radioiodine therapy. Effects on urinary iodine excretion in patients with differentiated thyroid carcinoma

AIM

Urinary iodine excretion (UIE) provides information about iodine supply and release. In the present study we investigated effects of the application of different radioiodine isotopes on UIE in patients with differentiated thyroid carcinoma (DTC).

PATIENTS, METHODS

In 91 consecutive patients with DTC UIE, measured as iodine/creatinine ratio, was determined before and after application of 123I and 131I for diagnostic or therapeutic purposes. Additionally, remnant volume (V) was determined prior to therapy. Group A consisted of 33 patients with supposed successful ablation of DTC. These patients received 370 MBq 131I for diagnostic use and served as controls. 58 patients (group B) with remnants, relapses and metastases received 370 MBq 123I for diagnostics prior to therapy with 1.5-22.2 GBq 131I. Factors influencing individual changes in urinary iodine excretion (deltaUIE) were investigated by using non-parametric tests.

RESULTS

In group A UIE did not change significantly after application of 131I. As well, UIE remained unchanged after diagnostic application of 123I in group B. In contrast, UIE increased significantly already 24 h after therapeutic application of 131I in this group. In patients with small remnants (V < 2.5 ml) a significant but only moderate increase of UIE could be observed (average increase: 47 microg I/g crea). In patients with larger remnants, with relapses or metastases increase of UIE values was significant and more pronounced.

CONCLUSIONS

It was confirmed that UIE increased significantly during radioiodine therapy in patients with DTC and radioiodine-accumulating tissue. The increase of UIE after therapeutic administration of radioiodine can be explained by the disintegrated thyroid follicles in thyroid remnants. The radioiodine-induced iodine release may be one reason for thyroid "stunning" even after application of diagnostic amounts of 131I.

Monitoring of a new approach of immunotherapy with allogenic (111)In-labelled NK cells in patients with renal cell carcinoma

The transfusion of allogenic, in vitro expanded natural killer cells (NKC) is a novel therapy option in oncology. To date, however, the biodistribution and kinetics of allogenic NKC have not been investigated. Therefore, in this study three patients with renal cell carcinoma received 3-7 x 10(8) NKC labelled with indium-111 oxine with a tenfold excess of unlabelled cells during NKC therapy. Whole-body scintigrams were obtained (0.5-144 h) in the anterior and posterior views. Scintigrams were analysed using a region of interest technique, and single-photon emission tomography (SPET) studies of the abdomen were performed. Results were compared to those obtained with polymerase chain reaction (PCR) of the peripheral blood (determination of foreign DNA, nested PCR, limit of detection 0.01%). Shortly after transfusion of NKC, more than 50% of the activity was accumulated in the lungs. We observed redistribution effects from lungs to liver, spleen and bone marrow. No significant loss of activity could be detected. In two of four large metastases, tracer accumulation could be proven by SPET. As confirmed by scintigrams and PCR, the fraction of circulating transfused cells was low at all times. Long-term activity retention might be caused either by survival of the allogenic cells, as confirmed by PCR (up to 3 days p.i.), or by phagocytosis of labelled cellular fragments. However, PCR data and uptake in metastases indicated long survival of a portion of allogenic NKC. Such long survival and low retention of the cells in the lung are requirements for an effective immunotherapeutic approach.

Comparing Early to Middle Miocene floras and probable vegetation types of Oberdorf N Voitsberg (Austria), Bohemia (Czech Republic), and Wackersdorf (Germany)

The Early Miocene vegetation of western Styria, Austria, is reconstructed on the basis of detailed investigations of leaves and diaspores from the mining area Oberdorf N Voitsberg. In this paper, the flora and probable vegetation are compared with other assemblages of similar age from the Czech Republic and Germany to elucidate the diversity of wetland and mesophytic plant communities. The floristic composition and the vegetational units represented in Oberdorf are compared to the middle part of the Most Formation (M Most Fm), Cypris Shale, Mydlovary Formation (Mydlovary Fm) of Bohemia, and the Wackersdorf mining area of Bavaria. Among these sites, Oberdorf is extremely poor in hydrophytes and reed-like monocotyledons, indicating rare pond-like habitats as well as possibly more closed swamp forest conditions than, e.g. in the M Most Fm. In Oberdorf, relatively high pH-values in the lignite-forming swamps and the possible scarcity of acidic, nutrient-poor (sandy) soils have probably influenced the floristic composition of the azonal communities. The peat-forming associations in all regions share the abundance of Glyptostrobus europaeus. However, distinct differences in the accompanying elements, such as Taxodium dubium (present and abundant only in the M Most Fm) indicate even stronger floristic variability of Early(/Middle) Miocene peat-forming and riparian plant communities than previously expected. The virtual absence of Pinus, Engelhardia, Comptonia, and probably also of Quercus kubinyii/Quercus drymeja in the megafossil record of Oberdorf can possibly be explained by the edaphic conditions. The abundance of Sequoia abietina (absent in all the other compared sites), which we assign to riparian (and mesophytic) forests in Oberdorf, may have been favoured by rich alluvial soils.In the mesophytic associations, thermophilous elements of the Lauraceae, Mastixiaceae, Symplocaceae, and Rutaceae are diverse. Usually they include Trigonobalanopsis rhamnoides/Trigonobalanopsis exacantha, an evergreen Fagaceae. This assemblage type corresponds with the Younger Mastixioid Flora sensu Mai. The Younger Mastixioid Flora is best developed in Wackersdorf, less distinct in Oberdorf, and likely in the Cypris Shale and Mydlovary Fm. It is not traceable in the M Most Fm.

Chronic inborn erythrocytosis leads to cardiac dysfunction and premature death in mice overexpressing erythropoietin

The most common cause of an increase of the hematocrit is secondary to elevated erythropoietin levels. Erythrocytosis is assumed to cause higher blood viscosity that could put the cardiovascular system at hemodynamic and rheological risks. Secondary erythrocytosis results from tissue hypoxia, and one can hardly define what cardiovascular consequences are caused by chronic erythrocytosis or hypoxia. Herein, a novel transgenic (tg) mouse line is characterized that is erythrocytotic because of chronic overexpression of the human erythropoietin gene. These mice grow up well, reaching a hematocrit of about 0.80 in adulthood. Blood volume of adult tg mice was markedly increased by 75%. Unexpectedly, blood pressure was not elevated and cardiac output was not decreased. Still, the adult tg mice showed features of cardiac dysfunction with increased heart weight. In vivo, high-frequency echocardiography revealed marked ventricular dilatation that was confirmed by histologic examination. Furthermore, by transmission electron microscopy, a prominent intracellular edema of the cardiomyocytes was seen. Exercise performance of the tg mice was dramatically reduced, unmasking the severity of their compromised cardiovascular function. In addition, life expectancy of the tg mice was significantly reduced to 7.4 months. Our findings suggest that severe erythrocytosis per se results in cardiac dysfunction and markedly reduced life span.

Radioiodine therapy in Graves' hyperthyroidism: determination of individual optimum target dose

The aim of this study was to investigate the results of different volume-dependent target doses on clinical outcome 6 months after radioiodine therapy (RITh) and its correlation with post therapeutic thyroid volumes (Vpost) in patients with Graves' disease. This analysis was designed to determine factors improving the results of radioiodine therapy without increasing target doses generally, as has been recommended recently. We studied consecutive data from 102 patients with Graves' disease, who had initial radioiodine therapy between 1991 and 1995. The 131I activities were calculated according to the formula of Marinelli. In addition to the normal calculation individual target doses were adjusted to the thyroid volumes of each patient before therapy. For statistical evaluation, the patients were divided into three subgroups of comparable sample sizes: Group I included those with a thyroid volume <15 ml before therapy. Group II included those ranging from a 15-25 ml volume before therapy and group III included those with thyroid volumes >25 ml. Laboratory thyroid parameters and thyroid volumes were measured in those groups before and 6 months after therapy.

RESULTS

Analysis of all patients revealed a significantly higher rate of hypothyroidism (54%) and fewer cases of hyperthyroidism (15%) six months after therapy in cases with Vpost smaller than 8 ml. The median Vpost needed to achieve an optimum therapeutic success rate (rate of eu- or hypothyroidism) was smaller than 5 ml in group I and smaller than 10 ml in group II. Therapeutic success was associated with different target doses in each group, 150,220 and 260 Gy for groups I, II, and III respectively.

CONCLUSIONS

Post therapeutic thyroid volumes correlated significantly with clinical outcome six months after therapy. An adjustment of the target doses based on thyroid volumes before therapy will lead to an appropriate reduction of thyroid volumes. Thus, in the individual case clinical outcome could be improved without applying higher target doses in all patients. This would ensure a better utilization of limited resources in medical care e.g. through a shorter hospital stay.