Positron emission tomography/computed tomography for early treatment response evaluation in metastatic colon cancer

614

Background: Treatment options for metastatic colon cancer (mCC) are widening. We prospectively evaluated serial 2-deoxy-2-[18F]fluoro-D-glucose (FDG) positron emission tomography/ computed tomography (PET/CT) and measurements of tissue inhibitor of metalloproteinases type 1 (TIMP-1), carcinoembryonic antigen (CEA) and urokinase plasminogen activator receptor domain I [uPAR(I)] for early assessment of treatment response in mCC patients. Methods: Thirty-three mCC patients scheduled for first line chemotherapy with capecitabine, oxaliplatin (CAPOX) and bevacizumab participated; 27 were evaluated by PET/CT before treatment, after one and four treatment series. Morphological and metabolic response was independently assessed according to Response Evaluation Criteria In Solid Tumours (RECIST1.1) and EORTC PET criteria. Plasma TIMP-1, plasma uPAR(I) and serum CEA were determined. Results: Metabolic response after one treatment course predicted the ability of CAPOX and bevacizumab to induce morphological response after four treatment series with a sensitivity of 80 %, specificity of 69 % and an Odds Ratio of 13.9 [CI 1.9; 182]. Early metabolically stable or progressive disease was associated with shorter progression-free survival (PFS) (hazard ratio (HR) = 3.2 [CI 1.3; 7.8]). Biomarker levels at early evaluation were associated to shorter PFS (TIMP-1 per unit increase on a log-2 transformed ng/mL scale: HR = 2.23 [CI 1.20; 4.14]; uPAR(I) per 25 fmol/mL increase: HR = 1.36 [CI 1.03; 1.79]). Conclusions: This monocentric study demonstrated predictive value of early metabolic PET response and prognostic value of TIMP-1 and uPAR(I) levels in mCC treated with CAPOX and bevacizumab. Results support investigation of PET/CT, TIMP-1 and uPAR(I) guided early treatment adaptation in mCC.

PET/MR in oncology: an introduction with focus on MR and future perspectives for hybrid imaging

After more than 20 years of research, a fully integrated PET/MR scanner was launched in 2010 enabling simultaneous acquisition of PET and MR imaging. Currently, no clinical indication for combined PET/MR has been established, however the expectations are high. In this paper we will discuss some of the challenges inherent in this new technology, but focus on potential applications for simultaneous PET/MR in the field of oncology. Methods and tracers for use with the PET technology will be familiar to most readers of this journal; thus this paper aims to provide a short and basic introduction to a number of different MRI techniques, such as DWI-MR (diffusion weighted imaging MR), DCE-MR (dynamic contrast enhanced MR), MRS (MR spectroscopy) and MR for attenuation correction of PET. All MR techniques presented in this paper have shown promising results in the treatment of patients with solid tumors and could be applied together with PET increasing the amount of information about the tissues of interest. The potential clinical benefit of applying PET/MR in staging, radiotherapy planning and treatment evaluation in oncology, as well as the research perspectives for the use of PET/MR in the development of new tracers and drugs will be discussed.

Toll-like receptor 4 Asp299Gly polymorphism in respiratory syncytial virus epidemics

The respiratory syncytial virus (RSV) antigen serves as ligand for Toll-like receptor (TLR) 4 that is a transmembrane signaling receptor in macrophages and dendritic cells. According to current evidence single nucleotide polymorphism involving amino acid 299 influences the susceptibility to severe RSV infections. The Asp299Gly allele has been shown to influence the TLR4-mediated signaling causing conformational change in the extracellular domain that recognizes pathogen-associated molecular patterns. The aim was to study the association between the TLR4 Asp299Gly polymorphism and the susceptibility to severe RSV bronchiolitis in infants. Altogether 312 cases and 356 controls, selected on the basis place of residence, date of birth, gender, and gestation at birth, were studied. When adjusted for multiple dependent variables, no allele or genotype frequency difference was found between the cases and the controls. Post hoc analysis revealed that during the year 2000 epidemics, the Gly299Gly genotype associated with protection against severe RSV and during 2004 epidemics Gly299Gly genotype and 299Gly allele associated with severe RSV. To conclude, we could not confirm the association of the Gly299 allele with severe RSV. This is consistent with the evidence that the susceptibility to severe RSV infection is principally dependent on environmental and constitutional factors. We propose that the risk of severe RSV infection may additionally depend on the interaction between individual TLR4 genotype and the particular RSV group causing bronchiolitis.

Surfactant protein B polymorphism and respiratory distress syndrome in premature twins

Recent evidence suggests that the susceptibility to respiratory distress syndrome (RDS) is partly explained by genetic variation in the surfactant proteins (SP) SP-A and SP-B. The present study was designed to evaluate the concordance difference method and candidate gene analysis, in parallel, for the investigation of genetic susceptibility to RDS. We studied 100 same-sex twin pairs with established RDS in at least one twin. The difference in RDS concordance rates between the monozygotic (MZ) and dizygotic (DZ) twin pairs as evidence of a genetic influence was evaluated, and the SP-A and SP-B genes were investigated for potential associations with the susceptibility to RDS. The concordance rates of RDS were 54 and 44% in the MZ and DZ pairs, respectively. The concordance difference of 10% was not significant [95% confidence interval (CI) -0.1 to +0.3, P=0.32], suggesting a low hereditary impact. However, the SP-B Ile131Thr polymorphism was associated with RDS. The threonine allele was associated with an increased risk of RDS [odds ratio (OR) 2.2, 95% CI 1.4-3.5, P=0.0014]. This was particularly apparent in first-born male infants (OR 6.2, 95% CI 2.4-16.3, P<0.001). The degree of prematurity (<32 weeks OR 2.0, 95% CI 1.1-3.7, P=0.021) and birth order (second-born OR 3.1, 95% CI 1.3-7.4, P=0.009) were the clinical variables affecting the risk of RDS. An association between the SP-B Ile131Thr polymorphism and RDS was found. The threonine allele was associated with the risk of RDS, particularly in the first-born twin infants. The concordance difference between MZ and DZ twin pairs underestimates the genetic impact on the risk of RDS. The traditional twin concordance study is insufficient to evaluate genetic predisposition to RDS or other diseases that are confounded by the birth order or multiple pregnancy in itself.

Association between surfactant protein A gene locus and severe respiratory syncytial virus infection in infants

Respiratory syncytial virus (RSV) causes seasonal epidemics of bronchiolitis among susceptible infants. Surfactant protein A (SP-A), a lung C-type lectin involved in innate host defense, opsonizes RSV and enhances phagocytosis. The candidate gene approach was used to investigate association of SP-A polymorphism with susceptibility to severe RSV infection. Genotype analysis was done for 86 infants with severe RSV infection and 95 matched control subjects. A significant difference in the frequency of SP-A2 was observed. The SP-A2 allele 1A(3) was overrepresented in RSV-infected infants, compared with control subjects (5% vs. 0.5%; P =.006), whereas allele 1A was underrepresented (1% vs. 6%; P =.011). The allele pool in which lysine was amino acid 223 was overrepresented in infants with severe RSV infection (28% vs. 18%; P =.023), whereas the allele pool in which proline was amino acid 99 was underrepresented (5% vs. 16%; P =.001). These results indicate that a genetic association exists between SP-A gene locus and severe RSV infection.

Respiratory distress syndrome: evaluation of genetic susceptibility and protection by transmission disequilibrium test

Based on epidemiological data and genetic association studies, neonatal respiratory distress syndrome (RDS) is a complex disease with a multigenic background. The genes coding for surfactant proteins (SP) A and B have been assigned as the most likely genes in the etiology of RDS. The major factor predisposing to RDS is prematurity, and thus the phenotype of a very premature newborn infant that does not develop the disease can be regarded as hypernormal. Altogether 107 father-mother-offspring trios were divided into two sets according to the proband's phenotype, to evaluate familial segregation of candidate gene polymorphisms by the transmission disequilibrium test. A set of 76 trios were analyzed for transmission disequilibrium from parents to affected offspring. Another set of 31 trios were studied for allele transmission from parents to hypernormal offspring born very prematurely before the gestational age of 32 weeks. SP-A1-A2 haplotype 6A(2)-1A(0) showed significant excess transmission to affected infants and SP-A1 allele 6A(2) decreased transmission to the hypernormals. The present family study provides strong support for a direct or indirect role of the SP-A alleles as genetic predisposers to RDS in premature infants. The inclusion of parent-hypernormal offspring trios in transmission disequilibrium test is a useful approach to test for genetic protection against a disease.

Surfactant protein-A gene locus associated with recurrent otitis media

Surfactant protein-A, which plays a role in innate host defense in the lung, is also expressed in the Eustachian tube. We report that the frequency of specific surfactant protein-A haplotypes and genotypes differs between children with recurrent otitis media compared with a control population.

Optimality principles and flow orderliness at the branching points of cerebral arteries

BACKGROUND AND PURPOSE

The cerebral arteries present an optimum blood flow/vessel radius relation. However, branch angles may vary widely in the cerebral arteries because the parametric optimization of branch angles is irrelevant in terms of energy cost. The position of the flow divider in extracranial arteries has been suggested to be optimum in flow orderliness. No data exist on the flow divider of cerebral arteries. Thus, we hypothesized that in the cerebral arteries the apex of the bifurcations, which is known to be the site of maximum hemodynamic stress in a vascular network, may normally lie in a non-optimum position relative to the dividing flow streamline in the parent vessel, leading to disturbed laminar flow and increased vessel wall shear stress at the apical region despite the optimum blood flow/vessel radius relation. The objective of this study was to test our hypothesis.

METHODS

We measured the branch angles and diameters of parent and branch segments of the anterior cerebral artery system from lateral projections to minimize the measurement error on angiographs chosen at random from normal sets. The position of the apex of the bifurcations in relation to the ostium of the parent artery (gamma) and the ratio of the branch diameters (d2/d1) were compared. Optimum curves for these parameters were calculated by a mathematical model. In addition, the separation of flow streamlines according to gamma was calculated for each bifurcation and related to the division of flow required by each branch according to the optimum blood flow/vessel radius relation.

RESULTS

The data points on gamma and d2/d1 and the separation of flow according to gamma and the division of flow required by the branches were found to scatter around the optimum curves. However, a trend toward the theoretical optimum is discernible. The data points are suggested to be a random sample from a normal distribution around the optimum (.40 < P < .50).

CONCLUSIONS

The bifurcations of the cerebral arteries appear to be optimized to avoid increased hemodynamic stresses both globally and locally in the same manner as extracranial arteries.

Vascular dimensions of the cerebral arteries follow the principle of minimum work

BACKGROUND AND PURPOSE

The principle of minimum work is a parametric optimization model for the growth and adaptation of arterial trees. It establishes a balance between energy dissipation due to frictional resistance of laminar flow (shear stress) and the minimum volume of the vascular system, implying that the radius of the vessel is adjusted to the cube root of the volumetric flow. The purpose of this study is to verify whether the internal carotid artery system obeys the principle of minimum work.

METHODS

Measurements of the radius of parent and branch segments of the internal carotid, anterior, and middle cerebral arteries were performed on analog angiographs chosen at random from a set classified as normal. The branch angles were measured from lateral projections in bifurcations of the anterior cerebral artery. The relation of the calibers of parent and branch vessels was analyzed.

RESULTS

The area ratio of the bifurcations (N = 174) was 1.2 +/- 0.4 (mean +/- SD). The equation (r0)n = (r1)n + (r2)n was solved for n, resulting in n = 2.9 +/- 0.7 (mean +/- SD, N = 157). Optimum proportions between the radii of parent (r0) and branch (r1 and r2) vessels in the internal carotid artery system were verified in normal carotid angiographs up to four branch generations, according to the theoretical equation r0(3) = r1(3) + r2(3) (r = 0.989, N = 174). No clear correlation was found between the measured branch angles, the relative branch cross-sectional area, and the theoretical optimum angles.

CONCLUSIONS

This study demonstrates that the process of branching of the internal carotid artery system obeys the principle of minimum work, as the diameter exponent approximates 3. The principle of minimum work establishes strict functional relations between volumetric flow, flow velocity, and vessel radius. This model was extended to parametric optimization of branch angles, which has proved irrelevant in terms of functional optimization. Our results corroborate this finding. Shear stress-induced endothelial mediation seems to be the regulating mechanism for the maintenance of this optimum vessel design. The magnitude of wall shear stress is the same at every point in a vascular network obeying the principle of minimum work, because the flow rate influences the shear stress proportionally to the third power of the vessel radius. This observation has implications for understanding the remodeling of the cerebral vascular network in the presence of arteriovenous malformations and for the pathogenesis of saccular aneurysms.

Cerebral blood flow in experimental intracranial mass lesions. Part II: The postdecompression phase

Cerebral haemodynamics were evaluated after a period of cerebral compression produced by subarachnoid fluid infusion or inflation of an epidural balloon. Release of the compression resulted in a marked cerebral hyperperfusion which was generalized in the case of hydrostatically raised pressure but restricted to supratentorial structures after balloon compression. A rebound of intracranial pressure (ICP) occurred only after balloon compression, indicating that loss of vasomotor tone per se was not the primary reason for the rebound of ICP. In the balloon compression experiments the hyperaemia passed into a stage of hypoperfusion attributable in part to a reduction in cerebral perfusion pressure due to the rebound of ICP and in part to an increase in flow resistance probably related to external compression of the vascular bed by the accumulation of brain oedema. The observed flow changes, i.e. delayed hypoperfusion preceded by hyperaemia, were similar to those after temporary ischaemia, indicating that the rebound response is a non-specific postischaemic phenomenon.

Cerebral blood flow in experimental intracranial mass lesions. Part I: The compression phase

We have shown that a rebound of intracranial pressure (ICP) occurring after decompression of an intracranial mass lesion is a threshold phenomenon dependent upon the cerebral perfusion pressure (CPP) during compression and the duration of the compression. In the present study regional cerebral blood flow (rCBF) was measured during balloon compression of a degree critical for the development of a postdecompression rebound. The effects were compared with those of hydrostatically raised pressure which under similar conditions rarely produces a rebound of ICP. Disproportionately marked reductions in flow occurred in the hemisphere ipsilateral to the balloon, especially in white matter and in cortex adjacent to the balloon with flow values of, respectively, 1.1 +/- 0.9 and 6.4 +/- 3.4 ml 100 g-1 min-1. The differences in flow between balloon and hydrostatic compression were found to be due to an increased cerebrovascular resistance (CVR) caused by a direct compressive effect by the balloon overriding the generalized vasodilation which occurs in response to the raised ICP. Thus the increase in CVR attributable to compression by the balloon added to the reduction in CPP caused by the diffuse increase in ICP. As a consequence flow in large regions of the brain was reduced below the thresholds for structural infarction and for ischaemic damage to the blood-brain barrier.

Embolization of cerebral arteriovenous malformations with bucrylate. Experience in a first series of 29 patients

The experience with embolization of intracerebral arteriovenous malformations (AVMs) with bucrylate (isobutyl-2-cyanoacrylate) in 29 patients is reported. In 9 cases (31%) less than 1/3 of the AVM nidus was occluded, in 12 (41%) 1/3 to 2/3, in 4 (14%) more than 2/3, and total occlusion was only seen in 3 cases (10%). One patient was never embolized, owing to procedure complications. At follow-up angiography in 20 patients, partial revascularization was found in 11 AVMs and further occlusion in 2. Complications occurred in 11 cases (38%). Five patients (17%) suffered from hemorrhage: 2 died, one deteriorated severely and 2 recovered. Unintentional embolization or edema resulted in neurologic deficits in 6 patients (21%), permanent in 3 and reversible in 3. Symptomatic improvement was initially found in 13 patients (45%) but was stable only in 9. In 9 patients (38%) embolization was followed by elective surgery or irradiation. The best results were obtained in small and medium-sized AVMs (less than 6 cm) while there was a high risk of complications and an uncertain palliative effect in large AVMs.

Effects of continuously expanding intracranial lesions on vital physiological parameters. An experimental animal study

The work described in this report confirms and extends the results described in a preliminary communication (Löfgren, J. and Zwetnow, N.N., Acta Neurol. Scand. (1970, 625) which examined the effects in cats of an expanding mass, in the form of an intracranial supratentorial balloon, on vital physiological parameters. In the present study, particular emphasis was placed on the possible significance of the rate of expansion of the mass in the range usually encountered in the clinical situation of intracranial haemorrhages. Results from the experiments on 37 cats and 8 dogs showed that changes in vital parameters appeared when the balloon had reached a volume of about 5% of the intracranial volume (the "reaction volume") while respiratory arrest occurred at an intracranial volume of about 10% (the "apnoea volume"). Both threshold volumes were independent of the rate of expansion within the range used. Alterations in EEG, heart rate, respiratory rate and systemic arterial pressure usually occurred simultaneously with the development of a transtentorial pressure gradient. When respiratory arrest occurred, the cerebral perfusion pressure was markedly reduced, usually to a value of about 30 mm Hg, suggesting that brain tissue ischaemia is an important component in the lethal mechanism underlying intracranial expanding lesions. It is proposed that the volume load tolerance of the organism towards an expanding intracranial lesion, as expressed by the reaction volume and the apnoea volume, may represent a biologically useful parameter potentially suitable for quantitative evaluation of adverse agents and therapeutic procedures.

Traumatic intracranial hematomas: pathophysiological aspects on their course and treatment

Hematomas in head injuries as a general rule reach their definite size within minutes after the trauma, the bleeding being effectively checked by an interaction of an increased intracranial pressure and the natural hemostatic processes. In epidural hemorrhage the development of arteriovenous shunting in the epidural space may result in continuing bleeding. In special circumstances vascular injury may produce delayed hemorrhage related to increased transmural pressure in the vascular bed and the development of a hyperfibrinolysis syndrome. The clinical effect of a hematoma is quantitatively related to its volume, but modified to a considerable degree in the particular case by the size of the extraaxial space and the arterial blood pressure. Some implications for treatment are commented upon.

Regional cerebral blood flow and CSF pressures during the Cushing response induced by an infratentorial expanding mass

An experimental study was carried out in eight dogs to investigate whether the Cushing response (CR) during intracranial hypertension is due to pressure per se, tissue distortion, or ischemia in the brain stem. To minimize the effects of rostrocaudal displacement, intracranial pressure was raised by an expanding mass lesion located in the posterior fossa. Regional cerebral blood flow (rCBF) was measured with radioactive microspheres and compartmental cerebrospinal fluid (CSF) pressures were recorded during the CR which was induced by the continuous inflation at a constant rate of an infratentorial epidural rubber balloon in two groups of four dogs. In one group (A) rCBF was measured at the onset of the CR and in the other group (B) at the peak of the systemic blood pressure rise. In the animals of group A blood flow in the mesencephalon, pons and upper medulla oblongata was reduced from control values by 32%, 57% and 85% respectively. In group B blood flow in the same areas did not differ significantly from pre-inflation values. In contrast, the recorded balloon volume, which was assumed to be an index of mechanical distortion of the brain stem, varied considerably at the beginning of the blood pressure rise (from 2.5 to 4.7% of the calculated intracranial space). Similarly, CSF pressure in the posterior fossa at the onset of the CR also varied considerably (from 52 to 117 mmHg). Thus, the large quantitative variations meant that both absolute pressure and tissue distortion were poor predictors of the onset of the CR. The findings suggest that ischemia, rather than brain stem distortion per se or pressure by itself, is responsible for the initiation of the CR. The rise in blood pressure elicited during the CR seems capable of restoring blood flow in the brain stem back to control values.

Incidence and prevalence of primary biliary cirrhosis in a defined population in Sweden

The incidence and prevalence of antimitochondrial antibody-positive primary biliary cirrhosis (PBC) has been studied within a defined area in Sweden served by one hospital. During the period 1976-1983 the yearly incidence of PBC was 1.4/10(5) inhabitants, and on 31 December 1983 the prevalence was 12.8/10(5) inhabitants. The prevalence is the highest reported so far. At the time of diagnosis half of the patients were clinically asymptomatic. Two of the patients also had celiac disease with osteomalacia responding to a gluten-free diet. Gallstone disease occurred in 30% of the patients. Four patients died--two of liver-related complications, one of colonic carcinoma, and one of staphylococcal septicemia and endocarditis. One further patient, who is still alive, developed hypernephroma. Our results indicate that PBC is a fairly benign disease in most patients, with a slow progress during which they lead a fairly normal life.

Influence of blood pressure on tolerance to an intracranial expanding mass

In 3 groups of 4 dogs with normotensive, induced-hypotensive and induced-hypertensive blood pressure respectively, continuous expansion of an extradural supratentorial balloon led to respiratory arrest at inflation volumes which increased with increasing blood pressure. This positive correlation between the volume tolerance to an expanding lesion and blood pressure was also found in similar experiments on 4 hypotensive and 4 hypertensive cats. Monitoring cerebrospinal fluid pressures in the cerebral lateral ventricles, in the posterior fossa and in the spinal subarachnoid space showed that absolute pressures in the various compartments as well as the intercompartmental pressure gradients at the moment of respiratory arrest were increased in proportion to the level of the systemic arterial pressure in each case. These observations do not support current concepts that brain-stem distortion alone or that stimulation of baroreceptors in the posterior fossa are responsible for eliciting the Cushing response. The fact that the supratentorial perfusion pressure was the only parameter which did not differ significantly under the different experimental conditions suggests that the mechanism responsible for the respiratory arrest is local brain tissue ischemia, probably near the tentorial incisure. The magnitude of gain in volume tolerance, when mean arterial pressure was varied from 60 mmHg to 190 mmHg, was 87% suggesting that the blood pressure may have a critical role in an intracranial lesion. These findings have clinical implications.

Arterio-venous epidural shunting in epidural bleeding radiological and physiological characteristics. An experimental study in dogs

In order to test the possibility suggested in previous studies that the long bleeding time and the large bleeding volume observed in experimental epidural bleeding can be explained by the development of an arterio-venous shunt, water soluble X-ray contrast was injected into the epidural space in dogs during an epidural bleeding in progress. It was found that the contrast medium left the epidural space through diploic veins in the cranial bone to the neck veins. By draining off epidural blood the arterio-venous shunt counteracts the intracranial pressure tamponade developing in intradural bleeds and thus prolongs bleeding. Perfusion experiments showed the absorption capacity for saline to be about 20 times as large in the epidural space as in the CSF space. While there was no apparent absorption limit for blood in the epidural space the absorption capacity for blood of the subarachnoid space became progressively saturated, leading to a continuously increasing CSF outflow resistance and CSF steady-state pressure. A theory for the formation of epidural haematoma is proposed which in essence implies that the epidural shunt is a major determinant of the clinical outcome of an epidural bleeding.