Selection of patients for resection of hepatic metastases: improved detection of extrahepatic disease with FDG pet.

A rapidly emerging clinical application of positron emission tomography (PET) is the detection of tumor tissue at whole-body studies performed with the glucose analogue 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG). High rates of recurrence after partial hepatic resection in patients with colorectal cancer liver metastases indicate that current presurgical imaging strategies are failing to show extrahepatic tumor deposits. Although FDG PET cannot match the anatomic resolution of conventional imaging techniques in the liver and the lungs, it is particularly useful for identification and characterization of extrahepatic disease. FDG PET can show foci of metastatic disease that may not be apparent at conventional anatomic imaging and can aid in the characterization of indeterminate soft-tissue masses. Several sources of benign and physiologic increased activity at FDG PET emphasize the need for careful correlation with findings of other imaging studies and clinical findings. FDG PET can improve the selection of patients for partial hepatic resection and thereby reduce the morbidity and mortality associated with inappropriate surgery.

Visual and semiquantitative analysis of 18F-fluorodeoxyglucose positron emission tomography using a partial-ring tomograph without attenuation correction to differentiate benign and malignant pulmonary nodules.

OBJECTIVE: Many studies have reported the use of attenuation-corrected positron emission tomography with 18F-fluorodeoxyglucose (FDG PET) with full-ring tomographs to differentiate between benign and malignant pulmonary nodules. We sought to evaluate FDG PET using a partial-ring tomograph without attenuation correction. METHODS: A retrospective review of PET images from 77 patients (range 38-84 years of age) with proven benign or malignant pulmonary nodules was undertaken. All images were obtained using a Siemens/CTI ECAT ART tomograph, without attenuation correction, after 185 MBq 18F-FDG was injected. Images were visually graded on a 5-point scale from "definitely malignant" to "definitely benign," and lesion-to-background (LB) ratios were calculated using region of interest analysis. Visual and semiquantitative analyses were compared using receiver operating characteristic analysis. RESULTS: Twenty lesions were benign and 57 were malignant. The mean LB ratio for benign lesions was 1.5 (range 1.0-5.7) and for malignant lesions 5.7 (range 1.2-14.1) (p < 0.001). The area under the ROC curve for LB ratio analysis was 0.95, and for visual analysis 0.91 (p = 0.39). The optimal cut-off ratio with LB ratio analysis was 1.8, giving a sensitivity of 95% and a specificity of 85%. For lesions thought to be "definitely malignant" on visual analysis, the sensitivity was 93% and the specificity 85%. Three proven infective lesions were rated as malignant by both techniques (LB ratio 2.6-5.7). CONCLUSIONS: FDG PET without attenuation correction is accurate for differentiating between benign and malignant lung nodules. Results using simple LB ratios without attenuation correction compare favourably with the published sensitivity and specificity for standard uptake ratios. Visual analysis is equally accurate.

Imaging features of primary and recurrent esophageal cancer at FDG PET.

Because of the poor prognosis for patients with esophageal cancer and the risks associated with surgical intervention, accurate staging is essential for optimal treatment planning. Positron emission tomography (PET) with 2-[fluorine-18]fluoro-2-deoxy-d-glucose (FDG) is a useful adjunct to more conventional imaging modalities in this setting. FDG PET is not an appropriate first-line diagnostic procedure in the detection of esophageal cancer and is not helpful in detecting local invasion by the primary tumor, and further studies are required to determine its efficacy in the detection of local nodal metastases. However, FDG PET is superior to anatomic imaging modalities in the ability to detect distant metastases. Metastases to the liver, lungs, and skeleton can readily be identified at FDG PET. In addition, FDG PET has proved valuable in determining the resectability of disease and allows scanning of a larger volume than is possible with computed tomography. Recurrent disease is readily diagnosed and differentiated from scar tissue with FDG PET. In addition, FDG PET may play a valuable role in the follow-up of patients who undergo chemotherapy and radiation therapy, allowing early changes in treatment for unresponsive tumors. The management of most patients with esophageal cancer can be improved with use of FDG PET.

FDG PET of recurrent or metastatic 131I-negative papillary thyroid carcinoma.

UNLABELLED: This study reports on the use of FDG PET in the follow-up of papillary thyroid cancer patients with negative findings on 131I total body scans and elevated levels of thyroglobulin after total thyroidectomy. METHODS: Eleven asymptomatic patients with previous papillary thyroid cancer, total thyroidectomy, 131I ablation, and treatment of all known metastases had negative findings on 131I total body scans after therapy but persisting elevations of thyroglobulin when not receiving thyroid hormone. All imaging before PET failed to show persisting tumor. FDG PET was performed on all patients while receiving full thyroid hormone replacement, except for the repeated scan of 1 patient (patient 6). After the PET scan, all patients were referred for supplementary CT, sonography, or biopsy of lesions in the neck. RESULTS: All 11 patients showed FDG uptake in the neck or upper mediastinum-in the initial scan in 10 and in a repeated scan in 1. Sonographically guided biopsy confirmed malignancy in 6, was nondiagnostic in 2, and showed normal findings in 1. In 2 patients, the sonographic results were normal and no biopsy was attempted. FDG imaging redirected the treatment of 7 patients, resulting in surgery and external beam radiotherapy in 3, surgery in 1, and external beam radiotherapy in 2. One patient declined further recommended surgery. The other 4 patients remain under observation. Surgical histopathology confirmed thyroid tumor in all 4 surgically treated patients. Retrospective review of the original histopathology slides showed no preponderance of aggressive histology. CONCLUSION: FDG PET is able to guide further evaluation of thyroid cancer patients who have elevated thyroglobulin levels and normal findings on 131I whole-body scanning.

Emerging role of PET in the diagnosis and staging of lung cancer.

Positron emission tomography (PET) with 18F-fluoro-2-deoxyglucose (FDG) has recently emerged as a practical and useful imaging modality in patients with lung cancer. Malignant tumours demonstrate increased uptake of FDG, a positron-emitting radiopharmaceutical. This increased FDG uptake in tumours can be seen using PET. FDG PET has much higher accuracy than other imaging modalities for the differentiation of benign and malignant lung nodules. The sensitivity of PET is 96% and the specificity 77% for diagnosing malignant nodules. PET is also more accurate than computed tomography (CT) for staging mediastinal nodal involvement (sensitivity 89%, specificity 94%). While CT relies on an arbitrary anatomical cutoff of 1 cm to diagnose malignant nodes, which may simply be enlarged due to inflammation, PET can accurately diagnose metastases in nodes smaller than 1 cm. Several studies have shown significantly better staging of distant metastases with FDG PET than with traditional techniques such as bone scanning. Differentiation of recurrent disease from scar tissue in the postoperative patient is often difficult with CT or magnetic resonance imaging. The low uptake of FDG in scar tissue allows reliable differentiation between scar tissue and a recurring tumour with PET. Early studies suggest a promising role for PET in the evaluation of response to chemotherapy. This may allow treatment to be changed after only one course of chemotherapy, instead of waiting for anatomical disease progression to become obvious clinically or with CT. Finally, significant improvements in cost effectiveness have been demonstrated when FDG PET is added to the preoperative work-up of patients with lung cancer.

Hepatic T2-weighted MRI: a prospective comparison of sequences, including breath-hold, half-Fourier turbo spin echo (HASTE).

The purpose of this study was to quantitatively compare the hepatic contrast characteristics of conventional spin-echo (CSE) and fast spin-echo (FSE) sequences with breath-hold T2-weighted images acquired with half-Fourier turbo spin echo (HASTE). Forty-five patients were examined with a phased-array surface coil. Nineteen patients had focal hepatic lesions, including eight malignant tumors, 10 cavernous hemangiomas, and one hepatic adenoma. Twenty-six patients had no focal hepatic lesions. T2-weighted images with comparable TE were acquired with CSE, FSE, and HASTE pulse sequences. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) for liver, spleen, and lesions were measured. FSE demonstrated significantly better quantitative performance than CSE for liver-spleen CNR (P .0084). No statistically significant difference was demonstrated between FSE and CSE for liver or spleen SNR. FSE demonstrated clear scan time and resolution advantages over CSE. HASTE performed significantly poorer than CSE and FSE for liver-spleen CNR (P < .0001), liver SNR (P = .0002 for CSE and P < .0001 for FSE), and spleen SNR (P < .0001). Optimized FSE images with a short echo train length performed comparably to CSE images of equivalent TE. Liver-lesion CNR was suppressed on HASTE images, suggesting that long echo train length FSE sequences could diminish solid lesion detection compared to CSE and short echo train length FSE.

Pulmonary deposition of salbutamol aerosol delivered by metered dose inhaler, jet nebulizer, and ultrasonic nebulizer in mechanically ventilated rabbits.

The deposition efficiency of three methods of aerosol delivery of salbutamol into lungs of ventilated rabbits was compared: 1) metered dose inhaler (MDI) with holding chamber (HC), 2) jet nebulizer (JN), and 3) ultrasonic (US) nebulizer. The latter system was tested using two different sized medication reservoirs, a large (20 mL) cup (US20) and a small (10 mL) cup (US10). After delivery of technetium-99m-labeled salbutamol aerosol, deposition in the lungs, trachea, and ventilator circuit were estimated by a gamma counter. Total pulmonary deposition [mean(SEM)] as a percentage of the prescribed drug was: MDI + HC 0.22(0.05)%; JN 0.48(0.05)%; US20 0.90(0.13)%; US10 3.05(0.49)%. Only the deposition from the US10 was statistically significantly higher than the other modes (p < 0.05). Dynamic scintigraphy showed that, among the nebulizers, the US10 continued to deliver medication for longer than either the JN or the US20. We conclude that the US10 appears to be more efficient in delivering aerosol to the lung in this rabbit model and merits further evaluation for clinical efficiency.

[18F]fluorodeoxyglucose uptake in neonatal acute lung injury measured by positron emission tomography.

The objective of this study was to evaluate positron emission tomography (PET) of [18F]fluorodexoyglucose (18FDG) uptake as a measure of neonatal acute lung injury. Inasmuch as intrapulmonary sequestration of neutrophils is a hallmark of acute lung injury, quantification of neutrophil activity using 18FDG may offer a novel, in vivo technique to examine the progression and resolution of this disease. Ten newborn piglets were studied: six received bronchoalveolar lavage followed by 4 h of high pressure ventilation of create acute lung injury. Four healthy piglets served as controls. 18FDG (0.8 mCi/kg; 29.6 MBq) was given i.v. and PET (ECAT 953/31, Siemens) was performed for 90 min. During PET, all animals were sedated, paralyzed, and ventilated to maintain normal blood gases. The time course of radioactivity in lung regions and in plasma was used to calculate the rate constant for the metabolic trapping of 18FDG in tissue according to the method of C. S. Patlak. Median 18FDG influx constants were significantly higher in injured piglets (0.0187 min-1) than in control piglets (0.0052 min-1) (p < 0.01). Moreover, consistent with the 18FDG uptake data, injured piglets had moderate to severe injury on lung histology whereas control piglets had only slight and focal histologic changes. We conclude that PET of 18FDG uptake is an accurate, readily repeatable in vivo measure of neonatal acute lung injury.

Efficiency of aerosol medication delivery from a metered dose inhaler versus jet nebulizer in infants with bronchopulmonary dysplasia.

The best means for optimal delivery of drugs into lungs of infants with bronchopulmonary dysplasia (BPD) is uncertain. We aimed to measure radio-aerosol deposition of salbutamol by jet nebulizer and metered dose inhalers (MDI) in ventilated and non-ventilated BPD infants. In a randomized, crossover sequence, salbutamol lung deposition was measured using an MDI (2 puffs or 200 micrograms) or sidestream jet nebulizer (5 minutes of nebulization with 100 micrograms/kg) in 10 ventilated (mean birthweight, 1,101 g) and 13 non-ventilated (mean birthweight, 1,093 g) prematurely born infants. Non-ventilated infants inhaled aerosol through a face mask, connected to a nebulizer or an MDI and spacer (Aerochamber). Ventilated infants received aerosol from an MDI + MV15 Aerochamber or a nebulizer inserted in the ventilator circuit. Lung deposition by both methods was low: mean (SEM) from the MDI was 0.67 (0.17)% of the actuated dose, and from the nebulizer it was 1.74 (0.21)% and 0.28 (0.04)% of the nebulized and initial reservoir doses, respectively. Corresponding figures for the ventilated infants were 0.98 (0.19)% from the MDI and 0.95 (0.23)% and 0.22 (0.08)% from the nebulizer. In both groups, and for both methods of delivery, there was marked inter-subject variability in lung deposition and a tendency for the aerosol to be distributed to the central lung regions.

Thrombin inhibitors reduce intrapulmonary accumulation of fibrinogen and procoagulant activity of bronchoalveolar lavage fluid during acute lung injury induced by pulmonary overdistention in newborn piglets.

We determined whether antithrombin (AT III) or hirudin (a specific thrombin inhibitor) reduce both the accumulation of fibrinogen in lung parenchyma and the procoagulant activity of bronchoalveolar lavage (BAL) fluid during acute lung injury induced by pulmonary overdistention. Newborn piglets were randomized to six-hourly infusions of AT III concentrate, a continuous infusion of recombinant hirudin, or no anticoagulant therapy. All animals were subjected to 24 h of identical mechanical ventilation at high peak pressures (3.9 kPa or 40 cm H2O). Tidal volumes were raised to a mean of 69 mL/kg in all three groups. Mean AT III levels in supplemented piglets (n = 22) were increased to 1.46 (SD 0.24) U/mL at 24 h, compared with 0.67 (SD 0.16) U/mL in controls (n = 23). The median activated partial thromboplastin time in animals receiving hirudin (n = 18) was prolonged to 53 s versus 34 s in untreated animals. The intrapulmonary accumulation of i.v. administered 125I-fibrinogen was reduced by AT III concentrate or hirudin, compared with untreated littermates (p = 0.003). The procoagulant activity of BAL fluid was also decreased by both thrombin inhibitors (p = 0.001). Intrapulmonary accumulation of fibrinogen and the procoagulant activity of BAL fluid were reduced by AT III or hirudin during lung injury caused by pulmonary overdistention. Future investigations should determine whether tangible clinical benefits result from this reduced potential for fibrin deposition in the injured lung.

Oscillating stereocontrol: a strategy for the synthesis of thermoplastic elastomeric polypropylene.

A strategy has been developed for the synthesis of thermoplastic elastomeric polypropylene based on the catalytic activity of the unbridged metallocene bis(2-phenylindenyl)zirconium dichloride [(2-PhInd)(2)ZrCl(2)]. This catalyst was designed to isomerize between achiral and chiral coordination geometries during the polymerization reaction to produce atactic-isotactic stereoblock polymers. The metallocene precursor (2-PhInd)(2)ZrCl(2) in the presence of methylaluminoxane polymerizes propylene to yield rubbery polypropylene. The isotacticity of the polymer, described by the isotactic pentad content, increases with increasing propylene pressure and decreasing polymerization temperature to produce polypropylenes with an isotactic pentad content ranging from 6.3 to 28.1 percent.

Tc-99m sulfur colloid demonstration of diffuse pulmonary interstitial extramedullary hematopoiesis in a patient with myelofibrosis. A case report and review of the literature.

A 60-year-old man with a myeloproliferative syndrome and extramedullary hematopoiesis had progressive respiratory and cardiac insufficiency during the previous 18 months, with advancing interstitial pulmonary disease on chest x-ray. During analysis of his respiratory disease, results of a transbronchial biopsy showed interstitial involvement with increased numbers of megakaryocytes and other panhematopoietic staining elements. Results of a bone marrow scan demonstrated diffuse replacement of pulmonary interstitium with bone marrow, as a component of known ongoing extramedullary hematopoiesis.

Isotope lung imaging.

The contribution of isotope imaging to the investigation of respiratory disease has been primarily limited to the detection of ventilation and perfusion abnormalities and the investigation of inflammation or cancer. In recent years, there has been a growing interest in the metabolic function of the lung and in measurements of alveolar capillary permeability in a variety of conditions. This review will deal with these newer applications of isotope techniques in the lung in addition to developments in ventilation-perfusion imaging.

Recurrent nerve palsy due to parathyroid cyst.

Cysts of the parathyroid gland are uncommon neck masses and difficult to diagnose. They can cause symptoms by endocrinological function or by pressure on surrounding structures. A case of recurrent nerve palsy due to a parathyroid cyst is presented. Aspiration of parathyroid cysts can be diagnostic and therapeutic in some cases.

Early adaptations in gas exchange, cardiac function and haematology to prolonged exercise training in man.

In order to determine the effect of short-term training on central adaptations, gas exchange and cardiac function were measured during a prolonged submaximal exercise challenge prior to and following 10-12 consecutive days of exercise. In addition, vascular volumes and selected haematological properties were also examined. The subjects, healthy males between the ages of 19 and 30 years of age, cycled for 2 h per day at approximately 59% of pre-training peak oxygen consumption (VO2) i.e., maximal oxygen consumption (VO2max). Following the training, VO2max (l.min-1) increased (P less than 0.05) by 4.3% (3.94, 0.11 vs 4.11, 0.11; mean, SE) whereas maximal exercise ventilation (VE,max) and maximal heart rate (fc,max) were unchanged. During submaximal exercise, VO2 was unaltered by the training whereas carbon dioxide production (VE) and respiratory exchange ratio were all reduced (P less than 0.05). The altered activity pattern failed to elicit adaptations in either submaximal exercise cardiac output or arteriovenous O2 difference. fc was reduced (P less than 0.05). Plasma volume (PV) as measured by 125I human serum albumin increased by 365 ml or 11.8%, while red cell volume (RCV) as measured by 51chromium-labelled red blood cells (RBC) was unaltered. The increase in PV was accompanied by reductions (P less than 0.05) in haematocrit, haemoglobin concentration (g.100 ml-1), and RBCs (10(6) mm-3). Collectively these changes suggest only minimal adaptations in maximal oxygen transport during the early period of prolonged exercise training. However, as evidenced by the changes during submaximal exercise, both the ventilatory and the cardiodynamic response were altered.(ABSTRACT TRUNCATED AT 250 WORDS)