Comparison of 2-dimensional and 3-dimensional acquisition for 18F-FDG PET oncology studies performed on an LSO-based scanner.

Three-dimensional (3D) PET acquisition has the potential to reduce image noise but the advantage of 3D PET for studies outside the brain has not been well established. To compare the performance of 2-dimensional (2D) and 3D acquisition for whole-body (18)F-FDG applications, a series of patient studies were performed using a lutetium oxyorthosilicate (LSO)-based tomograph. METHODS: Comparative 2D and 3D images were acquired for 27 oncology patients using an LSO-based tomograph. Data acquisition (350-650 keV, 6 ns) started 99 +/- 12 min (mean +/- SD) after injection of 624 +/- 76 MBq (18)F-FDG. Bias caused by tracer redistribution and decay was eliminated by acquiring dynamic data over a single-bed position using a protocol that alternated between septa-in and septa-out modes (2D, 3D, 2D, 3D, 2D, 3D). Frames were combined to form 8 statistically independent sinograms: four 2D replicates (105 s) and four 3D replicates (90 s). The different frame durations in 2D and 3D compensated for the different number of overlapping bed positions required for an 85-cm whole-body study. Images were reconstructed with either 2D or fully 3D ordered-subsets expectation maximization (2 iterations and 8 subsets; 2D 6-mm gaussian, 3D 5- and 6-mm gaussian). Image target-to-background ratio was assessed by dividing the lesion maximum by the mean within a neighboring background region. Image noise was assessed by applying background regions of interest to the replicate images and calculating the within-patient coefficient of variation. RESULTS: The difference in target-to-background ratio between the 2D and 3D images, when they were filtered with 6-mm and 5-mm gaussian filters, respectively, was not highly statistically significant (P = 0.16). The mean ratio of 3D to 2D image values was 0.94 with 95% limits of agreement of 0.63-1.41. The within-patient coefficients of variation for the 2D and 3D images were 13% +/- 15% and 9% +/- 10%, respectively (P = 0.0005). CONCLUSION: Under conditions of matched target to-to-background ratios, the 3D mode was found to produce images with significantly less variability than the 2D mode. These data provide support for the use of 3D acquisition with LSO detectors to reduce scan times in whole-body (18)F-FDG applications.     

Benign intracranial hypertension and recombinant growth hormone therapy in Australia and New Zealand

Benign intracranial hypertension (BIH) is reported in three children from Australia and one from New Zealand, who were being treated with recombinant human growth hormone (rhGH). Three males and one female, aged between 10.5 and 14.2 y, developed intracranial hypertension within 2 weeks to 3 months of starting treatment. A national database, OZGROW, has been prospectively collecting data on all 3332 children treated with rhGH in Australia and New Zealand from January 1986 to 1996. The incidence of BIH in children treated with growth hormone (GH) is small, 1.2 per 1000 cases overall, but appears to be greater with biochemical GHD (<10IUml ^-1), i.e. 6.5/1000 (3 in 465 cases), relative risk 18.4, 95% confidence interval 1.9-176.1, than in all other children on the database. The incidence in patients with Turner's syndrome was 2.3/1000 (1 in 428 cases). No cases in patients with partial GHD (10–20 IUml ^-1) or chronic renal failure were identified. Possible causative mechanisms are discussed. The authors'practice is now to start GH replacement at less than the usual recommended dose of 14IUm-² week^-1 in those children considered to be at high risk of developing BIH. Ophthalmological evaluation is recommended for children before and during the first few months following commencement of rhGH therapy and is mandatory in the event of peripheral or facial oedema, persistent headaches, vomiting or visual symptoms. The absence of papilledema does not exclude the diagnosis.     

Hemoperitoneum secondary to rupture of cystic artery pseudoaneurysm

BACKGROUND:Spontaneous hemoperitoneum of hepato- biliary origin is commonly due to hemorrhage from a liver tumor.It is rarely caused by spontaneous rupture of aneurysm in visceral arteries. METHODS:We report an unusual case of hemoperitoneum caused by rupture of cystic artery pseudoaneurysm,and also outline the approach to its management through surgical and radiological methods. RESULTS:In our patient,the pseudoanurysm was initially treated with percutaneous thrombin injection.However this method of treatment failed after initial success.The pseudoanurysm was finally obliterated successfully using microcoil embolization. CONCLUSIONS:The mainstay of treatment of cystic artery pseudoaneurysm is cholecystectomy and ligation of the aneurysm.Recent publications showed success in using microcoil embolisation.In this case we also outline the use of percutaneous thrombin injection as a definitive treatment method and discuss its success or failure as a new method of treatment.     

Philanthotoxin blocks quisqualate-, AMPA- and kainate-, but not NMDA-, induced excitation of rat brainstem neurones in vivo.

1. The effect of electrophoretic ejection of philanthotoxin (the polyamine toxin, from the Egyptian digger wasp) was tested on responses of brainstem and spinal neurones in the pentobarbitone-anaesthetized rat to excitatory amino acids. 2. Philanthotoxin caused a dose-dependent reduction of responses to quisqualate, alpha-amino-3-hydroxy-5-phenyl-4-isoxazolepropionate (AMPA) and kainate with little effect on those to N-methyl-D-aspartate (NMDA). 3. The time-course of this antagonist action was slow. In particular the rate of recovery was dependent on frequency of ejection of the agonist. This agonist-dependent recovery suggests that philanthotoxin has a channel blocking mode of action on mammalian central neurones.     

Successful outcome after resection of lung, liver and diaphragm for locally advanced lung cancer.

A 63-year-old man presented with a 2 month history of intermittent right subcostal and shoulder tip pain. Preoperative imaging confirmed a locally advanced right lower lobe lung tumour involving the diaphragm and liver. Bronchoscopic biopsy confirmed squamous cell carcinoma and mediastinoscopy was negative. The patient underwent a right bilobectomy with resection of the right hemi-diaphragm and a right hemi-hepatectomy. His postoperative recovery was satisfactory and he remains well 18 months after the surgery. We believe that in selected cases, patients with locally advanced lung tumours invading the liver may have a survival advantage following resection.     

Pharmacological characterization of non-NMDA subtypes of glutamate receptor in the neonatal rat hemisected spinal cord in vitro.

1. A grease-gap technique was used to record depolarizing responses to alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionate (AMPA), kainate and N-methyl-D-aspartate (NMDA) in the hemisected spinal cord of the neonatal rat. The pharmacology of non-NMDA subtypes of glutamate receptor was investigated with the novel quinoxalinedione, 2,3-dihydroxy-6-nitro-7-sulphamoyl-benzo (F)-quinoxaline (NBQX) and with a series of barbiturates. 2. NBQX antagonized AMPA- and kainate-, but not NMDA- induced depolarizations. The near parallel shifts of the major part of the dose-response curves for AMPA and kainate by NBQX gave pA2 values (+/- s.e.) of 6.7 +/- 0.2 and 6.8 +/- 0.2 respectively, consistent with a common site of action for these two agonists. 3. Below the 50% level at which these pA2 values were calculated, however, an NBQX-resistant plateau was seen within the kainate, but not the AMPA, dose-response curve. 4. In decreasing order of potency, methohexitone, secobarbitone, thiopentone, pentobarbitone and phenobarbitone preferentially reduced kainate-, rather than AMPA- and NMDA-, induced depolarizations. Methohexitone was also the most selective with IC50S against kainate, AMPA and NMDA of 31 +/- 7, 172 +/- 47 and greater than 200 microM respectively. 5. The NBQX-resistant plateau seen within the kainate dose-response curve was reduced by methohexitone. Kainate antagonism by methohexitone was not reduced by 50 microM picrotoxin. 6. We conclude that, while mixed agonist actions may hamper demonstration of antagonist selectivity, depolarizations induced by the non-NMDA ionotropic agonists, AMPA and kainate, are mediated in part via distinct receptors.