Optimal scan time for evaluating pancreatic disease with positron emission tomography using F-18-fluorodeoxyglucose

OBJECTIVE: Image interpretation in positron emission tomography (PET) using F-18-fluoro-2-deoxy-D-glucose (FDG) is usually performed for images obtained at 1 h postinjection (PI) of FDG, but it remains unknown whether this is the optimal time for imaging patients with pancreatic disease. The aim of this study was to assess the optimal scan time for FDG-PET for patients suspected of having pancreatic cancer. PATIENTS AND METHODS: Forty-four patients with suspected pancreatic cancer underwent FDG-PET scans at both 1 h and 2 h PI. Tracer uptake in the pancreatic lesions and possible liver metastasis was interpreted qualitatively, using a 5-point grading system (0 = normal, 1 = probably normal, 2 = equivocal, 3 = probably abnormal, and 4 = definitely abnormal) by 4 nuclear medicine physicians independently, who were blind to all clinical information. Detection performance with each image was compared using receiver operating characteristic (ROC) analysis. An average score of the 4 readers for each patient was also defined as consensus average index (CAI) and compared between the two images. RESULTS: ROC results indicated no significant differences in detection performance (Averaged areas under ROC curves of 1 h vs. 2 h were 0.92 vs. 0.90 for primary tumor, and 0.81 vs. 0.85 for liver metastases). There were no significant differences in CAIs between 1 h and 2 h PI images in interpreting primary tumor and positive liver metastases, but a significant difference was observed for cases without liver metastases (p < 0.05). CONCLUSIONS: The certainty of excluding liver metastases was increased when the 2h image was used, although ROC analysis did not establish a difference between 1 h and 2 h imaging for differentiating malignant and benign lesions in primary pancreatic cancer or its liver metastases.     

Dosimetric Assessment of the Field Abutment Region in Head and Neck Treatments Using a Multileaf Collimator

BACKGROUND AND PURPOSE: The use of conventional asymmetric collimators for junctioning of abutted fields can lead to significant dose inhomogeneity, due to jaw misalignment. However, recent technologic advances enable us to fabricate much finer leafpositioning accuracy. Consequently, it is anticipated that the use of multileaf collimator (MLC) will potentially improve dose homogeneity at the junction of abutted fields. In this work, we evaluated the dose inhomogeneities at the match-plane in monoisocentric three-field head and neck setups, using MLC for field abutment. MATERIAL AND METHODS: To define either the anterior or the lateral fields, the MLC was used with either the longitudinal (0 degree angle) or the transverse (90 degree angle) settings. For 0 degree setting, each leaf moves in a direction perpendicular to the gantry rotation axis, hence the "tongue and groove" (T&G) design can effect matching-area dose at the side of the leaf (Figure 1a). For 90 degree setting, the rounded shape of the leaf produces its effect at the leaf end (Figure 1b). Four combinations of abutted anterior field and abutted lateral field defined by MLC, i.e., abutted using MLC side-by-side, side-by-end, end-by-side and end-by-end, were compared (Table 1). Dose inhomogeneity was measured at the junction of the two abutted fields with films in a solid water phantom (Figure 2). The effect of jaw settings as a backup diaphragm on the dose distribution was also studied. Reproducibility of the results was confirmed by repeated measurements over a 1-year period. RESULTS: Abutted fields using MLC side-by-side caused underdose of approximately 15% (Figure 3a). Abutted fields using MLC side-by-end produced > 10% overdose that could be improved to +/- 1% for 0.5 mm overlap of the leaf end from the lateral portals (Figure 4). When using end-by-side, an overdose of approximately 15% was observed. However, the dose improved to a homogeneous dose for 0.8 mm overlap of leaf end from the anterior portal (Figure 5). End-by-end showed an overdose of > 20% (Figure 3b). This overdose could be smoothed out by overlaps of both leaf ends by 0.8 mm from both lateral and anterior portals (Figure 6). The ideal jaw position was found to be at 1 mm away from the beam central axis in any combination (Table 2). CONCLUSION: The use of MLCs for photon field junction matching is appropriate and represents an alternative approach to the problem of field matching using the asymmetric jaws in head and neck treatments.     

Structural and functional characterization of gastric mucosa and central nervous system in histamine H2 receptor-null mice

To examine the physiological role of the histamine H(2) receptor, histamine H(2) receptor-null mice were generated by homologous recombination. Histamine H(2) receptor-null mice, which developed normally and were fertile and healthy into adulthood, exhibited markedly enlarged stomachs and marked hypergastrinemia. The former was due to hyperplasia of gastric gland cells (small-sized parietal cells, enterochromaffin-like cells and mucous neck cells which were rich in mucin), but not of gastric surface mucous cells, which were not increased in number as compared with those in wild-type mice despite the marked hypergastrinemia. Basal gastric pH was slightly but significantly higher in histamine H(2) receptor-null mice. Although carbachol but not gastrin induced in vivo gastric acid production in histamine H(2) receptor-null mice, gastric pH was elevated by both muscarinic M(3) and gastrin antagonists. Thus, both gastrin and muscarinic receptors appear to be directly involved in maintaining gastric pH in histamine H(2) receptor-null mice. Interestingly, gastric glands from wild-type mice treated with an extremely high dose of subcutaneous lansoprazole (10 mg/kg body weight) for 3 months were very similar to those from histamine H(2) receptor-null mice. Except for hyperplasia of gastric surface mucous cells, the findings for gastric glands from lansoprazole-treated wild-type mice were almost identical to those from gastric glands from histamine H(2) receptor-null mice. Therefore, it is possible that the abnormal gastric glands in histamine H(2) receptor-null mice are secondary to the severe impairment of gastric acid production, induced by the histamine H(2) receptor disruption causing marked hypergastrinemia. Analyses of the central nervous system (CNS) of histamine H(2) receptor-null mice revealed these mice to be different from wild-type mice in terms of spontaneous locomotor activity and higher thresholds for electrically induced convulsions. Taken together, these results suggest that (1) gastrin receptors are functional in parietal cells in histamine H(2) receptor-null mice, (2) abnormal gastric glands in histamine H(2) receptor-null mice may be secondary to severe impairment of gastric acid production and secretion and (3) histamine H(2) receptors are functional in the central nervous system.     

Pathophysiology and Treatment of Streptococcal Toxic Shock Syndrome

We have recently encountered three cases of streptococcal toxic shock syndrome, each of which had a different cause. All the patients had inflammation of soft tissue in the lower extremities, and developed shock and multiple organ failure immediately after the clinical visit. The inflammation of soft tissue was necrotising fasciitis in one case, myositis in one case, and phlegmon in one. In the first case the debridement was incomplete, which resulted in an extensive ulceration. Wary of repeating this experience, we made an early diagnosis and did a thorough debridement in the second case. The patient was ultimately discharged without complications. It is rare that a patient with extensive myositis survives without amputation of the extremity. The third patient responded well to early treatment with antibiotics.     

BD focalpoint slide profiler performance with atypical glandular cells on SurePath Papanicolaou smears

BACKGROUND:

The FocalPoint Slide Profiler is an automated cervical cytology screening system that is approved for primary screening. It identifies up to 25% of slides as requiring No Further Review. However, few studies have evaluated FocalPoint performance with glandular abnormalities.

METHODS:

Sixty‐six SurePath Papanicolaou (Pap) tests with a diagnosis of atypical glandular cells were identified. A total of 172 Pap tests with a diagnosis of “endometrial cells present” were included as controls. Follow‐up histology was abnormal if diagnosed as high‐grade squamous intraepithelial lesions, adenocarcinoma in situ, carcinoma, or complex endometrial hyperplasia. The FocalPoint software ranked each case into 1 of 7 categories: quintiles 1 (high risk) through 5 (low risk), No Further Review, and Process Review.

RESULTS:

A total of 215 slides were qualified for review; 38 (57.6%) atypical glandular cells cases were abnormal on follow‐up biopsy, and 27 (71.1%) atypical glandular cells with abnormal follow‐up qualified for review; no cases were classified No Further Review, and 9 (33%) were ranked in quintile 1. Twenty‐three (82.1%) atypical glandular cells with benign follow‐up were qualified for review; 3 (11%) cases were classified No Further Review, and 4 (17%) were ranked in quintile 1. There was a statistically significant difference between the ranking of benign atypical glandular cells cases, abnormal atypical glandular cells cases, and control cases (P = .03). However, when collapsed into No Further Review versus all other quintiles, the differences were not significant (P = .20).

CONCLUSIONS:

The FocalPoint Slide Profiler did not classify glandular lesions with abnormal follow‐up in the No Further Review category. However, these cases were not preferentially ranked in quintile 1. FocalPoint‐screened slides need to be carefully reviewed for glandular abnormalities, regardless of the quintile ranking. Cancer (Cancer Cytopathol) 2010. © 2010 American Cancer Society.     

Evaluation of the efficacy of a small CdTe gamma-camera for sentinel lymph node biopsy

We previously reported the basic performance of a prototype small cadmium telluride (CdTe) gamma-camera (SSGC) intended for use in radioguided surgeries. In this study, we sought to confirm the favorable previous results and to extend the preliminary findings to examine the efficacy of the SSGC in an animal study and a clinical setting for sentinel lymph node biopsy. METHODS: The prototype SSGC (1,024 pixels; field of view, 44.8 x 44.8 mm), equipped with a parallel-hole collimator, was used in both animal and clinical studies. 99mTc-phytate (18.5 MBq) was injected into the tongues and legs of 6 rabbits. In the clinical study, 74 MBq of 99mTc-phytate was injected into peritumoral regions in 8 patients with oral cancer. The detection of hot nodes by the SSGC was compared with that by a conventional scintillation gamma-camera (CGC). RESULTS: The SSGC detected 29 hot nodes in images of 6 rabbits after injection. The number of hot nodes was the same as the number seen in CGC studies, but the CGC required a longer acquisition time to produce comparable images. There were no differences between the SSGC and the CGC in terms of activity ratios and hot node-to-background ratios. The biodistribution of 99mTc-phytate in removed tissues was evaluated by contact radiography, and radioactivity was assayed with a gamma-well counter. The mean +/- SD radioactivity in specimens was 0.15% +/- 0.15%, with a range of 0.01%-0.62%. In the clinical study, the SSGC detected 30 hot nodes with a 5- to 60-s acquisition time at 4 h after injection. The SSGC documented all hot nodes depicted by the CGC at 4 h after injection. CONCLUSION: The SSGC showed significant potential for the detection of sentinel lymph nodes in lymphoscintigraphy. The results of the studies suggested that the SSGC facilitates the exploration of hot nodes in sentinel lymph node biopsy.     

Cardiac sympathetic nerve activity during kainic acid–induced limbic cortical seizures in rats

We sought to define changes in cardiac sympathetic nerve activity that occur during seizures. We studied kainic acid–induced limbic cortical seizures in urethane-anesthetized rats using cardiac sympathetic nerve, blood pressure, and electrocardiography (ECG) recordings. We studied changes in ventilation rate before and during seizures. Cardiac sympathetic nerve activity was increased during limbic cortical seizures. The modest increases were similar to changes induced by nitroprusside infusion. The normal relation of cardiac sympathetic nerve activity to ventilation rate was lost during seizure activity. Changes in cardiac sympathetic nerve activity caused by changes in ventilation rate became unpredictable, and could be extreme. We conclude that the modest changes in cardiac sympathetic nerve activity contribute to the predominantly parasympathetic effects on the heart during limbic cortical seizures and periods of asphyxia. Further, ventilation rate changes might be associated with large sudden increases or decreases in cardiac sympathetic outflow during seizures.