Blood flow measurements with [(15)O]H2O and [18F]fluoride ion PET in porcine vertebrae.

A dual positron emission tomography (PET) tracer study with [18F]fluoride and the freely diffusible tracer [(15)O]H2O was performed to measure the capillary transport of [18F]fluoride and to evaluate the potential of [18F]fluoride ion PET to quantitate bone blood flow. Under the condition of a high predictable single-pass extraction fraction (E(F)) for [18F]fluoride, the [18F]fluoride ion influx transport constant (K1F), derived from kinetic [18F]fluoride ion PET measurements, can be used to estimate bone blood flow. Bone blood flow was measured in vertebral bodies by dynamic [(15)O]H2O PET during continuous ventilation with N2O, O2, and Isoflurane (FiO2 = 0.3) in seven adult mini pigs, followed by dynamic [18F]fluoride ion PET. The mean blood flow measured by [(15)O]H2O (FlowH2O) was 0.145 +/- 0.047 ml x minute(-1) x ml(-1) and the mean K1F was 0.118 +/- 0.031 ml x minute(-1) x ml(-1), respectively (mean +/- SD). Regional analysis showed excellent agreement between FlowH2O and K1F at low flow and a significant underestimation of flow by K1F relative to FlowH2O in regions of normal and elevated flow. The observed relationship between parameters followed the Renkin-Crone distribution. The permeability-surface product was determined as 0.25 minute(-1) for vertebral bodies consisting of a mixture of trabecular and cortical bone. We conclude that [18F]fluoride ion PET can be used to estimate bone blood flow in low and normal flow regions, as long as the flow dependency of the E(F) is taken into consideration. Above blood flow values of 0.2 to 0.35 ml x minute(-1) x ml(-1), the magnitude of K1F is increasingly independent on blood flow because diffusion limits tracer transport.

Diminished glucose transport and phosphorylation in Alzheimer's disease determined by dynamic FDG-PET.

UNLABELLED: Using dynamic [18F]fluorodeoxyglucose (FDG) and PET, kinetic rate constants that describe influx (K1) and efflux (k2) of FDG as well as phosphorylation (k3) and dephosphorylation (k4) were determined in patients with probable Alzheimer's disease and similarly aged normal controls. METHODS: The regional cerebral metabolic rate for glucose (CMRglu) was calculated from individually fitted rate constants in frontal, temporal, parietal and occipital cerebral cortex, caudate nucleus, putamen, thalamus and cerebellar cortex. Dynamic PET scans were obtained in normal controls (n = 10, mean age = 67) and Alzheimer's disease patients (n = 8, mean age = 67) for 60 min following injection of 10 mCi of FDG. RESULTS: The Alzheimer's disease group was characterized by decreases of the CMRglu ranging from 13.3% in the frontal to 40.9% in the parietal cortex, which achieved significance in all regions except the thalamus. K1 was significantly reduced in the parietal (p < 0.01) and temporal cortices (p < 0.05). Significant declines in k3 were found in the parietal (p < 0.005), temporal and occipital cortex, and in the putamen and cerebellum (p < 0.05). The rate constants k2 and k4 were unchanged in the Alzheimer's disease group. CONCLUSION: These data suggest that hypometabolism in Alzheimer's disease is related to reduced glucose phosphorylation activity as well as diminished glucose transport, particularly in the most metabolically affected areas of the brain, the parietal and temporal cortex.

Determination of regional rate constants from dynamic FDG-PET studies in Parkinson's disease.

UNLABELLED: Dynamic [18F]fluorodeoxyglucose (FDG) PET was used in Parkinson's disease patients and normal controls to determine kinetic rate constants for FDG. The goal was to assess whether the metabolic decreases observed in Parkinson's disease are associated with transport or phosphorylation processes or both. METHODS: Fluorine-18-FDG was administered to 18 Parkinson's disease and 15 normal control subjects. Dynamic PET scanning was performed for 1 h and rate constants were obtained by nonlinear, least-squares analysis. Regional glucose metabolic rate was calculated from the individually fitted rate constants and by two standard static scan analyses. RESULTS: Global CMRglu was decreased in Parkinson's disease (mean reduction 22%), reaching statistical significance in all regions investigated. K1 was significantly reduced in parietal cortex, temporal cortex and striatum while k3 was significantly reduced only in parietal cortex. The rate constant k2 was unchanged. CONCLUSION: K1, k3 and CMRglu all demonstrated greater deficits across the brain with progression of disease and development of dementia, particularly in the parietal an occipital cortex. This suggested that the metabolic disturbance may be a global dysfunction throughout the brain. Because altered rate constants are specifically taken into account, dynamic measurements has shown to provide higher sensitivity for detecting diminished glucose utilization in Parkinson's disease than static approaches.

Assessment of porcine bone metabolism by dynamic.

UNLABELLED: The aim of this study was to quantify regional bone blood flow and [(18)F]fluoride ion influx with [(18)F]fluoride ion PET and correlate the results with specific static and dynamic indices of bone metabolism in healthy pigs. METHODS: During continuous ventilation (fractional concentration of oxygen in inspired gas = 0.3), dynamic PET scans 120 min in duration were obtained for 9 mini pigs after intravenous injection of 10.0 +/- 1.2 MBq (mean +/- SD) of [(18)F]fluoride ion per kilogram of body weight. Iliac crest bone biopsies were performed immediately before the PET scan to determine static and dynamic indices of bone metabolism (i.e., the mineral apposition rate) by bone histomorphometry. Kinetic rate constants describing influx (K(1)) and efflux (k(2)) of [(18)F]fluoride as well as chemisorption and incorporation of [(18)F]fluoride (k(3)) and reverse transport (k(4)) were determined for 6 vertebral bodies in each animal. Blood flow estimates (f) were derived from K(1) values corrected for the permeability-surface area product using a previously derived correction algorithm. A rate constant describing the net forward transport rate of fluoride (K(i)) and the fluoride volume flux (K(flux)) derived from a 2-tissue-compartment model was calculated and compared with the results of Patlak graphic analysis (K(pat)). RESULTS: A significant correlation was found between mineral apposition rate and K(i) (P < 0.005), K(flux) (P < 0.01), K(pat), K(1), and f (P < 0.05). The values of f, K(i), K(flux), and K(pat) did not correlate significantly with other static or dynamic histomorphometric indices or with age, serum alkaline phosphatase, or parathyroid hormone levels. The values of f and K(i) correlated linearly (y = 0.023 + 0.32x; r(2) = 0.74; P < 0.001). CONCLUSION: PET bone studies using [(18)F]fluoride ion provide quantitative estimates of bone blood flow and metabolic activity that correlate with histomorphometric indices of bone formation in the normal bone tissue of the mini pig. Therefore, it seem reasonable to assume that [(18)F]fluoride ion PET can reduce the number of invasive bone biopsies, thus facilitating follow-up of patients with metabolic bone diseases.

Computer-assisted infusion and nutrition planning in an intensive care burn unit.

The paper describes a computer-assisted infusion and nutrition programme, running on an IBM-compatible PC/XT or PC/AT, for a surgical intensive care unit specializing in burn treatment. Using inputs of patient and laboratory data relevant to infusion planning, the programme generates a schedule for balanced enteral or parenteral nutrition of adult and adolescent patients from the age of 14 upwards. Potential side effects and metabolic complications in nutrition therapy are minimized. Graphics provide a rapid status check on individual parameters whenever required.

Dependency of the [18F]fluoromisonidazole uptake on oxygen delivery and tissue oxygenation in the porcine liver.

We have previously shown that the accumulation of fluorine-18-labeled fluoromisonidazole ([(18)F]FMISO) is inversely correlated to tissue oxygenation, allowing the quantification of porcine liver tissue hypoxia in vivo. We determined the activity from administered [(18)F]FMISO in relation to the hepatic oxygen availability and the partial pressure of oxygen in tissue (tPO(2)) to define a critical oxygen delivery on a regional basis. [(18)F]FMISO was injected 2 h after onset of regional liver hypoxia due to arterial occlusion of branches of the hepatic artery in 10 domestic pigs. During the experimental procedure the fractional concentration of inspired oxygen (FiO(2)) was set to 0.67 in group A ( N=5) and to 0.21 in group B ( N=5) animals. Immediately before sacrifice, the tPO(2) was determined in normal flow and flow-impaired liver segments. The standardized uptake values (SUV) for [(18)F]FMISO was calculated from 659 single tissue samples obtained 3 h after injection of approximately 10 MBq/kg body weight [(18)F]FMISO and was compared with the regional total hepatic oxygen delivery (DO(2)) calculated from the regional arterial and portal venous flow (based on (141)Ce- and (99m)Tc-microspheres measurements) and the oxygen content of the arterial and portal venous blood. In 121 tPO(2)-measured liver tissue samples, the mean DO(2) was significantly decreased in occluded liver tissue samples [group A: 0.063 (0.044-0.089); group B: 0.046 (0.032-0.066)] compared to normal flow segments [group A: 0.177 (0.124-0.252); group B: 0.179 (0.128-0.25) mL x min(-1) x g(-1); geometric mean (95% confidence limits); p < 0.01 in group A and p < 0.001 in group B]. The tPO(2) of occluded segments [group A: 5.1 (3.2-8.1); group B: 3.9 (2.4-6.2) mm Hg] was significantly decreased compared to normal flow segments [group A: 20.2 (12.6-32.5); group B: 22.4 (14.3-35.2) mm Hg; p < 0.01 in group A and p < 0.001 in group B]. Three hours after [(18)F]FMISO administration, the mean [(18)F]FMISO SUV determined in tPO(2)-measured occluded segments was significantly higher [group A: 4.08 (3.12-5.34), group B: 5.43 (4.14-7.13)] compared to normal liver tissue [group A: 1.57 (1.2-2.06), group B: 1.5 (1.16-1.93); p < 0.001 for both groups]. The [(18)F]FMISO SUV allowed prediction of the tPO(2) with satisfying accuracy in hypoxic regions using the exponential regression curve [[(18)F]FMISO=1.05+6.7((-0.117 tPO(2))); r(2)=0.75; p < 0.001]. In addition, regardless of ventilation conditions, a significant exponential relationship between the DO(2) and the [(18)F]FMISO SUV was found ( r(2)=0.39, p < 0.001). Our results suggest that the reduction of the oxygen delivery below the critical range of 0.1-0.11 mL x min(-1) x g(-1) regularly causes liver tissue hypoxia. The severity of hypoxia is reflected by the [(18)F]FMISO accumulation and allows the in vivo estimation of the tPO(2) in hypoxic regions.

Allogeneic cancellous bone graft and a Burch-Schneider ring for acetabular reconstruction in revision hip arthroplasty.

BACKGROUND: There is an ever-increasing number of failed hip arthroplasties associated with massive deficiency of acetabular bone stock consisting of a segmental or cavitary defect. This study was undertaken to evaluate the long-term results after use of morselized cryopreserved allogeneic bone graft and an antiprotrusio cage to treat such a deficiency. METHODS: From January 1, 1988, to January 1, 1994, forty-one patients (forty-one hips) with an acetabular defect classified as type IIl or IV according to the American Academy of Orthopaedic Surgeons system were operated on with use of a Burch-Schneider ring and morselized cryopreserved allogeneic cancellous bone graft. Thirty-eight patients (thirty-eight hips) were available for clinical and radiographic follow-up examinations at an average of 7.3 years (range, 4.2 to 9.4 years) after surgery. RESULTS: All measured clinical parameters had improved significantly by the time of the follow-up examination (p < 0.0001). Radiographs confirmed that none of the thirty-eight hips had any measurable migration or displacement of the acetabular component and that osseous consolidation occurred only within the grafted area in all patients. CONCLUSION: Acetabular reconstruction with use of morselized cryopreserved allogeneic cancellous bone graft and the Burch-Schneider ring can be highly successful in managing massive acetabular deficiencies in revision hip arthroplasty.

Use of Pseudomonas hyperimmunoglobulin to treat septic shock in burn cases.

The progress of 18 episodes of septic shock in nine patients with burn injuries after administration of a Pseudomonas immunoglobulin is presented. In nine instances the septic shock was treated successfully. The mean burn index of these nine patients was 96. In six of the nine patients the septic shock was accompanied by simultaneous inhalation trauma and in six by acute kidney failure. In four cases the sepsis was caused by P. aeruginosa and in five by staphylococci. Despite the different causative agents, successful treatment was possible in these cases. The mean burn index for the four patients who eventually died was 119; all patients in this group were suffering from an inhalation trauma and acute kidney failure requiring dialysis. In these cases even the use of Pseudomonas immunoglobulin had no decisive effect.

Hypoxia PET/CT imaging: implications for radiation oncology.

Hypoxia, a condition of reduced partial pressure of oxygen in tissue, is an important determinant of poor tumor response to radiation treatment. Many invasive and non-invasive methods and approaches have been investigated to detect tumor hypoxia for response prediction and to facilitate modulation of radiation treatment. In this review we discuss the biological consequences of tumor hypoxia, methods of measuring regional tumor hypoxia with positron emission tomography (PET) tracers and applications for radiation oncology.

Probe-guided localization of cancer deposits using [18F]fluorodeoxyglucose.

In recent years, several probes have been developed to allow for the intraoperative detection of tumour tissue using [18F]fluorodeoxyglucose (FDG). Detector designs include high-energy gamma and beta probes, as well as combination devices with background rejection capabilities. Some laboratory prototypes and commercialized systems have demonstrated reasonable sensitivities for 511 keV photons and /or b particles emitted from 18F for in vivo use. This review focuses on the ability of these devices to detect tumour deposits in the low-contrast environment of the operating room . Important technical and biological factors that influence tumour-to-background contrast are discussed and potential future applications and developments are highlighted. In addition, we evaluate the limited data on absorbed doses resulting from [18F] FDG administration immediately prior to surgery that indicate acceptable levels of radiation exposure to operating room personnel.

Tumour hypoxia imaging with [18F]FAZA PET in head and neck cancer patients: a pilot study.

PURPOSE: Hypoxia is an important negative prognostic factor for radiation treatment of head and neck cancer. This study was performed to evaluate the feasibility of use of (18)F-labelled fluoroazomycin arabinoside ([(18)F]FAZA) for clinical PET imaging of tumour hypoxia. METHODS: Eleven patients (age 59.6 +/- 9 years) with untreated advanced head and neck cancer were included. After injection of approximately 300 MBq of [(18)F]FAZA, a dynamic sequence up to 60 min was acquired on an ECAT HR+ PET scanner. In addition, approximately 2 and 4 h p.i., static whole-body PET (n = 5) or PET/CT (n = 6) imaging was performed. PET data were reconstructed iteratively (OSEM) and fused with CT images (either an external CT or the CT of integrated PET/CT). Standardised uptake values (SUVs) and tumour-to-muscle (T/M) ratios were calculated in tumour and normal tissues. Also, the tumour volume displaying a T/M ratio >1.5 was determined. RESULTS: Within the first 60 min of the dynamic sequence, the T/M ratio generally decreased, while generally increasing at later time points. At 2 h p.i., the tumour SUV(max) and SUV(mean) were found to be 2.3 +/- 0.5 (range 1.5-3.4) and 1.4 +/- 0.3 (range 1.0-2.1), respectively. The mean T/M ratio at 2 h p.i. was 2.0 +/- 0.3 (range 1.6-2.4). The tumour volume displaying a T/M ratio above 1.5 was highly variable. At 2 h p.i., [(18)F]FAZA organ distribution was determined as follows: kidney > gallbladder > liver > tumour > muscle > bone > brain > lung. CONCLUSION: [(18)F]FAZA PET imaging appears feasible in head and neck cancer patients, and the achieved image quality is adequate for clinical purposes. Based on our initial results, [(18)F]FAZA warrants further evaluation as a hypoxia PET tracer for imaging of cancer.

PET and PET/CT studies of tumor tissue oxygenation.

Hypoxia has been identified as a major adverse prognostic factor for tumor progression and for resistance to anticancer treatment. Various approaches have been evaluated to assess tumor hypoxia in vivo. PET imaging in particular has emerged as a promising non-invasive tool to accurately characterize tumor oxygenation, thus offering the potential to optimize and individualize a therapy for patients suffering from cancer. The current PET tracers and animal models for the study of tissue hypoxia including aspects of small animal PET imaging are reviewed in this paper. Special emphasis is placed on human PET studies assessing tumor hypoxia in patients with different tumor entities, various anticancer therapies (chemotherapy, radiation therapy, hypoxia targeting chemotherapy) as well as studies deriving prognostic factors and outcome data. Methodological advantages underpinning PET/CT in the imaging of hypoxia are discussed. The great promise of PET/CT is its potential as a single imaging modality for whole body staging providing both anatomical and biological information on the tumor as a whole. It allows a more precise estimation of the hypoxic tumor volume as well as comparisons on a voxel-by-voxel basis (parametric mapping). Finally, PET and PET/CT are discussed in the framework of individualized therapies with its special significance for intensity modulated radiation therapy and selective dose escalation in hypoxic tumor regions as well as more systemic approaches such as hypoxia-directed cytotoxins.

Prevalence of vertebral alterations and the effects of calcium and vitamin D supplementation on calcium metabolism and bone mineral density after gastrectomy.

BACKGROUND: Bone disease is common after gastrectomy, resulting in decreased bone mass and an increased risk of fracture. No proven therapy is currently available. METHODS: Serum markers of calcium metabolism in 98 patients after partial or total gastrectomy were compared with those in 30 age- and sex-matched healthy controls. Patients with disorders of calcium metabolism were investigated by conventional radiography and single-energy computed tomography of the spine. Forty patients participated in a 1-year follow-up study to investigate the effects of vitamin D and calcium supplementation on calcium metabolism and bone mineral density. RESULTS: Altered serum markers of calcium and phosphate metabolism were observed in 77 (79 per cent) of 98 patients. Sixty (79 per cent) of these had vertebral alterations. Vertebral fractures were detected in 22 patients, grade I vertebral deformities in 50 patients, grade II deformities in 22 patients and osteopenia (Z-score less than - 1) in 30 patients. Calcium and vitamin D supplementation resulted in an increase in 25-hydroxy-vitamin D (P < 0.001), 1,25-dihydroxy-vitamin D (P = 0.048) and osteocalcin (P = 0.045), whereas levels of parathyroid hormone were decreased (P = 0.007). Bone mineral density did not change over time. CONCLUSION: Disturbances of calcium and bone metabolism are common after gastrectomy. Calcium and vitamin D supplementation normalized levels of markers of calcium metabolism and might have prevented age-related bone mass loss, although it did not increase bone mineral density after 1 year.

[Receptor-binding capacity for estrogens and progesterone in the uterine cervix during the menstrual cycle and in the postmenopausal period]. / Die Rezeptor-Bindungs-kapazität für Ostrogene und Progesteron in der Cervix uteri während des Zyklus und in der Postmenopause.

In biochemical studies it was found that the binding capacity of cytoplasmatic estrogen and progesterone receptors in the uterine cervix undergo characteristic changes during the menstrual cycle. The highest estrogen binding values were observed by the eighth day, after which there was a significant drop. The highest progesterone binding values were around the twelfth day, followed by a significant drop after ovulation. In sexually mature subjects the estrogen receptors predominated in the mucosa and the progesterone receptors in the myometrium. Therefore, there is obviously a parallel to the receptor content in the corpus uteri. The maximum estrogen and progesterone binding capacities were in each case ascertained some days before the maximum E2 and Pr values were attained in the serum. Hence, the estrogen receptors have already built up in the uterine cervix before optimal functional activity, measured by the cervix score, has been attained. Anti-estrogens given at the beginning of the cycle can disturb this sequence. The high estrogen receptor content in the endometrium at the beginning of the cycle creates the necessary conditions for the explosive, proliferative gland growth around this time, even though the serum estrogen concentration is still relatively low. In the postmenopause the estrogen binding capacity in the uterine cervix was higher than during sexual maturity, while the reverse was the case with the progesterone binding capacity.

[Functional results after suture repair in ruptures of the long biceps tendon with special consideration of subacromial impingement]. / Funktionelle Behandlungsergebnisse nach Durchflechtungsnaht bei Rupturen der langen Bizepssehne. Unter besonderer Berücksichtigung eines subakromialen Impingements.

Operative treatment for ruptures of the long biceps tendon still is discussed controversially. In the present literature the keyhole-technique is recommended according to favourable biomechanical conditions. In recent years refixation to the short biceps tendon was preferred. Now it is supposed that this technique may provoke subacromial impingement considering the loss of depression function of the long biceps tendon to the humeral head. Between 1980 to 1991 83 patients with rupture of the long biceps tendon were treated operatively by refixation to the short head. 28 patients were investigated after an average follow-up of 6.5 years. Due to the criteria of the Constant-Score 85% of patients achieved very good, 15% good results. At our patients provocation of a subacromial impingement could not be observed. The subacromial space was not reduced in the postoperative x-ray control. Compared with the non-operated shoulder isokinetic determination of isometric maximal peak torque for elbow-flexion, shoulder-abduction and shoulder-flexion yield to almost identical results for the operated shoulder. Refixation to the short head can be advised for treatment of ruptures of the long biceps tendon due to the certain technique with a low complication rate and very good functional outcome.

Allogenic bone graft viability after hip revision arthroplasty assessed by dynamic [18F]fluoride ion positron emission tomography.

The biological fate of allogenic bone grafts in the acetabular cavity and their metabolic activity after acetabular augmentation is uncertain but is most important for the stability of hip implants after hip revision arthroplasty. The aim of this study was to quantify regional bone metabolism after hip replacement operations. Dynamic [18F]fluoride ion positron emission tomography (PET) was used to investigate the metabolic activity of acetabular allogenic bone grafts and genuine bone, either 3-6 weeks (short-term group, n = 9) or 5 months to 9 years (long-term group, n = 10) after hip revision arthroplasty. Applying a three-compartment model, the fluoride influx constant was calculated from individually fitted rate constants (Knlf) and by Patlak graphical analysis (Kpat). The results were compared with genuine cancellous and cortical acetabular bone of contralateral hips without surgical trauma (n = 7). In genuine cortical bone, Knlf was significantly increased in short- (+140.9%) and long-term (+100.0%) groups compared with contralateral hips. Allogenic bone grafts were characterised by a significantly increased Knlf in the short-term group (+190.9%) compared with contralateral hips, but decreased almost to the baseline levels of contralateral hips (+45.5%) in the long-term. Values of Knlf cor-related with the rate constant K1 in genuine (r = 0.89, P<0.001) and allogenic bone regions (r = 0.79, P<0.001), indicating a coupling between bone blood flow and bone metabolism in genuine bone as well as allogenic bone grafts. Kpat values were highly correlated with Knlf measurements in all regions. In conclusion, [18F]fluoride ion PET revealed the presence of an increased host bone formation in allogenic bone grafts early after hip revision arthroplasty. In contrast to genuine cortical bone, allogenic bone graft metabolism decreased over time, possibly due to a reduced ability to respond to the same extent as genuine bone to elevated metabolic demands after surgery.

Introducing fluorine-18 fluoromisonidazole positron emission tomography for the localisation and quantification of pig liver hypoxia.

Fluorine-18 labelled fluoromisonidazole ([18F]FMISO) has been shown to accumulate in hypoxic tissue in inverse proportion to tissue oxygenation. In order to evaluate the potential of [18F]FMISO as a possible positron emission tomography (PET) tracer for imaging of liver tissue hypoxia, we measured the [18F]FMISO uptake in 13 domestic pigs using dynamic PET scanning. Hypoxia was induced by segmental arterial hepatic occlusion. During the experimental procedure the fractional concentration of inspired oxygen (FiO2) was set to 0.67 in group A (n=6) and to 0.21 in group B (n=7) animals. Before and after arterial occlusion, the partial pressure of O2 in tissue (TPO2) and the arterial blood flow were determined in normal flow and flow-impaired liver segments. Standardised uptake values [SUV=kBq tissue (in g) / body weight (in kg) x injected dose (in kBq)] for [18F]FMISO were calculated from PET images obtained 3 hours after injection of about 10 MBq/kg body weight [18F]FMISO. Immediately before PET scanning, the mean arterial blood flow was significantly decreased in arterially occluded segments [group A: 0. 41 (0.32-0.52); group B: 0.24 (0.16-0.33) ml min-1 g-1] compared with normal flow segments [group A: 1.05 (0.76-1.46); group B: 1.14 (0.83-1.57) ml min-1 g-1; geometric mean (95% confidence limits); P<0.001 for both groups]. After PET scanning, the TPO2 of occluded segments (group A: 5.1 (4.1-6.4); group B: 3.5 (2.6-4.9) mmHg] was significantly decreased compared with normal flow segments [group A: 26.4 (21.2-33.0); group B: 18.2 (13.3-25.1) mmHg; P<0.001 for both groups]. During the 3-h PET scan, the mean [18F]FMISO SUV determined in occluded segments increased significantly to 3.84 (3.12-4.72) in group A and 5.7 (4.71-6.9) in group B, while the SUV remained unchanged in corresponding normal liver tissue [group A: 1.4 (1.14-1. 71); group B: 1.31 (1.09-1.57); P<0.001 for both groups]. Regardless of ventilation conditions, a significant inverse exponential relationship was found between the TPO2 and the [18F]FMISO SUV (r2=0. 88, P<0.001). Our results suggest that because tracer delivery to hypoxic tissues was maintained by the portal circulation, the [18F]FMISO accumulation in the liver was found to be directly related to the severity of tissue hypoxia. Thus, [18F]FMISO PET allows in vivo quantification of pig liver hypoxia using simple SUV analysis as long as tracer delivery is not critically reduced.