S Stroobants

Utility of Positron Emission Tomography for the Staging of Patients With Potentially Operable Esophageal Carcinoma

PURPOSE A prospective study of preoperative tumor-node-metastasis staging of patients with esophageal cancer (EC) was designed to compare the accuracy of 18-F-fluoro-deoxy-D-glucose (FDG) positron emission tomography (PET) with conventional noninvasive modalities. PATIENTS AND METHODS Seventy-four patients with carcinomas of the esophagus (n = 43) or gastroesophageal junction (n = 31) were studied. All patients underwent attenuation-corrected FDG-PET imaging, a spiral computed tomography (CT) scan, and an endoscopic ultrasound (EUS). RESULTS FDG-PET demonstrated increased activity in the primary tumor in 70 of 74 patients (sensitivity: 95%). False-negative PET images were found in four patients with T1 lesions. Thirty-four patients (46%) had stage IV disease. FDG-PET had a higher accuracy for diagnosing stage IV disease compared with the combination of CT and EUS (82% v 64%, respectively; P: =.004). FDG-PET had additional diagnostic value in 16 (22%) of 74 patients by upstaging 11 (15%) and downstaging five (7%) patients. Thirty-nine (53%) of the 74 patients underwent a 2- or 3-field lymphadenectomy in conjunction with primary curative esophagectomy. In these patients, tumoral involvement was found in 21 local and 35 regional or distant lymph nodes (LN). For local LN, the sensitivity of FDG-PET was lower than EUS (33% v 81%, respectively; P: =.027), but the specificity may have been higher (89% v 67%, respectively; P: = not significant [NS]). For the assessment of regional and distant LN involvement, compared with the combined use of CT and EUS, FDG-PET had a higher specificity (90% v 98%, respectively; P: =. 025) and a similar sensitivity (46% v 43%, respectively; P: = NS). CONCLUSION PET significantly improves the detection of stage IV disease in EC compared with the conventional staging modalities. PET improves diagnostic specificity for LN staging.

Lymph node staging in non-small-cell lung cancer with FDG-PET scan: a prospective study on 690 lymph node stations from 68 patients.

PURPOSE To compare the accuracy of computed tomography-(CT) scan and the radiolabeled glucose analog 18F-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) visually correlated with CT (PET + CT) in the locoregional lymph node (LN) staging of non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS Sixty-eight patients with potentially operable NSCLC underwent thoracic CT, PET, and invasive surgical staging (ISS). Imaging studies were read prospectively and blinded to the surgical and pathologic data. A five-point visual scale was used for the interpretation of LNs on PET. Afterwards, with knowledge of the pathology, the relationship between standardized uptake values (SUVs) and the presence of metastasis in LNs was explored in a receiver operating characteristic (ROC) analysis, and the likelihood ratios (LRs) for SUVs of LNs were determined. RESULTS ISS was available for 690 LN stations. CT correctly identified the nodal stage in 40 of 68 patients (59%), with understaging in 12 patients and overstaging in 16 patients. PET + CT was accurate in 59 patients (87%), with understaging in five patients and overstaging in four patients. In the detection of locally advanced disease (N2/N3), the sensitivity, specificity, and accuracy of CT were 75%, 63%, and 68%, respectively. For PET + CT, this was 93%, 95%, and 94% (P = .0004). In the ROC curve, the best SUV threshold to distinguish benign from malignant LNs was 4.40. The analysis with this SUV threshold was not superior to the use of a five-point visual scale. The LR of a SUV less than 3.5 in an LN was 0.152; for a SUV between 3.5 and 4.5, it was 3.157; and for a SUV greater than 4.5, it was 253.096. CONCLUSION PET + CT is significantly more accurate than CT alone in LN staging of NSCLC. A five-point visual scale is as accurate as the use of an SUV threshold for LNs in the distinction between benign and malignant nodes. The very high negative predictive value of mediastinal PET could reduce the need for mediastinal ISS in NSCLC substantially.

Clinical Value of [18F]fluoro-Deoxyglucose Positron Emission Tomography for Patients with Fever of Unknown Origin

We describe the diagnostic contribution of [ 18 F]fluoro-deoxyglucose (FDG) positron emission tomography (PET) scan in 58 consecutive cases of fever of unknown origin (FUO) and compare this new approach with gallium scintigraphy. This investigation was performed from March 1996 through October 1998 at Gasthuisberg University Hospital in Leuven, Belgium. A final diagnosis was established for 38 patients (64%). Forty-six FDG-PET scans (79%) were abnormal; 24 of these abnormal scans (41% of the total number of scans) were considered helpful in diagnosis, and 22 (38% of the total number) were considered noncontributory to the diagnosis. In a subgroup of 40 patients (69%), both FDG-PET and gallium scintigraphy were performed. FDG-PET scan and gallium scintigraphy were normal in 23% and 33% of these cases, respectively; helpful in diagnosis in 35% and 25%, respectively; and noncontributory in 42% each. All foci of abnormal gallium accumulation were also detected by use of an FDG-PET scan. We conclude that FDG-PET is a valuable second-step technique in patients with FUO because it yielded diagnostic information in 41% of the patients in whom the probability of a definite diagnosis was only 64%. FDG-PET scan compares favorably with gallium scintigraphy for this indication. Because of the quick results (within hours instead of days), FDG-PET scan may replace gallium scintigraphy as a radiopharmaceutical for the evaluation of patients with FUO.

Synthesis of well-ordered nanopores by anodizing aluminum foils in sulfuric acid

Well-ordered nanostructures were produced on industrial aluminum foils by one-, two-, and three-step anodizing processes performed in sulfuric acid at cell potentials between 15 and 25 V. Almost perfect triangular lattices of nanopores were obtained by the two- and three-step anodizing processes. It was found that the third step in the anodizing process neither significantly improves the ordering of the pores nor enlarges the size of the well-ordered domains. The effective growth rate of the oxide layer was calculated for various cell potentials and compared with literature data. The effect of the anodizing time on the ordering of pores and the size of the domains was established. The pore diameters and the interpore distances were evaluated for various cell potentials, too. Anodizing in sulfuric acid results in small pore sizes and interpore distances compared to the ones obtained by anodizing in phosphoric and oxalic acids.

The role of positron emission tomography with 18F-fluoro-2-deoxy-D-glucose in respiratory oncology

In the past 5 yrs, positron emission tomography (PET) with 18F-fluoro-2-deoxy-D-glucose (FDG) has become an important imaging modality in lung cancer patients. At this time, the indication of FDG-PET as a complimentary tool to computed tomography in the diagnosis and staging of nonsmall cell lung cancer has gradually gained more widespread acceptance and also reimbursement in many European countries. This review focuses on the data of FDG-PET in the diagnosis of lung nodules and masses, and in locoregional and extrathoracic staging of nonsmall cell lung cancer. Emphasis is put on the potential clinical implementation of the currently available FDG-PET data. The use of FDG-PET in these indications now needs further validation in large-scale multicentre randomized studies, focusing mainly on treatment outcome parameters, survival and cost-efficacy. Interesting findings with 18F-fluoro-2-deoxy-D-glucose-positron emission tomography have also been reported for the evaluation of response to radio- or chemotherapy, in radiotherapy planning, recurrence detection and assessment of prognosis. Finally, a whole new field of application of positron emission tomography in molecular biology, using new radiopharmaceuticals, is under extensive investigation.

18-FDG PET scan in the staging of recurrent melanoma: additional value and therapeutic impact

Staging of melanoma patients by means of whole body functional imaging in a single evaluation session using positron emission tomography (PET) with fluorine-18- labelled deoxy-d-glucose (FDG) as a metabolic tracer has created much interest over the last decade. After enthusiastic pilot studies, more attention has been paid to the false-negative and false-positive results of this technique than to its true therapeutic impact. This study aimed to evaluate (1) the sensitivity and specificity of this technique at a single lesion level compared with conventional screening procedures (CSP) – both of these accompanied by careful clinical examination; and (2) the additional value of the PET scan at the level of the individual patient and its therapeutic impact for different types of melanoma recurrence. A consecutive series of 100 PET scans performed on 84 melanoma patients with regional or distant recurrence according to CSP (89 PET scans) or suspicion of recurrence, i.e. inconclusive CSP (11 PET scans), were retrospectively analysed and compared with the CSP results. At the single lesion level, PET scan and CSP showed a sensitivity of 85 and 81%, a specificity of 90 and 87% and an accuracy of 88 and 84%, respectively. PET provided false-negative results for small skin metastases and brain involvement; false-positive results were associated with unrelated benign or malignant tumours and peripheral soft tissue and bone uptake. PET scan showed an additional value over and above CSP at the individual patients level by true upstaging in 10 cases, true downstaging in 24 cases and depiction of more lesions within the same stage of disease in 15 cases. The overall therapeutic impact reached 26%: 17 out of 71 (24%) cases with regional recurrence, one out of 18 cases (5.5%) with distant metastasis and eight out of 11 cases (73%) with suspicion of recurrence where CSP remained doubtful. However, in 19 cases comparison between CSP and PET resulted in discordant findings, suggesting upstaging in one area and downstaging at another site within the same patient. In conclusion, PET scan has an additional value in the staging of recurrent melanoma, providing it is accompanied by careful clinical examination and specific brain imaging. However, in the absence of evidence of metastasis or unrelated conditions at the same site on CSP, PET spots may represent false-positive images, which would falsely upgrade a patient to an incurable state, or they may be early true-positive findings, which will become evident during close follow-up.

Detection of extrapulmonary lesions with integrated PET/CT in the staging of lung cancer

The aim of the present study was to assess retrospectively the additional value of positron emission tomography (PET)/computed tomography (CT) in the detection of unexpected extrapulmonary lesions in the staging of patients with a malignant pulmonary lesion in comparison with CT and PET used alone. A total of 217 patients with a pathologically proven lung tumour underwent PET/CT. CT, PET and PET/CT were evaluated in the detection of extrapulmonary lesions. These abnormalities were compared with the final diagnosis obtained from the medical records and statistical analysis was carried out. In total, 108 lesions were clinically detected. PET/CT showed a sensitivity, specificity, positive and negative predictive values and accuracy of 100, 81, 71, 100 and 87%, respectively, for the detection of extrapulmonary lesions and 92, 98, 89, 98 and 97%, respectively, for the detection of malignant extrapulmonary lesions. PET/CT was significantly better than CT and PET used alone. Conventional staging work-up has a poor sensitivity in detecting second primary cancers or unexpected metastases. The detection of malignant extrapulmonary lesions is necessary for correct tumour staging. By combining both metabolic and anatomical information, positron emission tomography/computed tomography is able to depict more unexpected extrapulmonary lesions than computed tomography and positron emission tomography used alone, and positron emission tomography/computed tomography provides more additional information of malignancy or benignancy of lesions detected with one of the two imaging modalities alone.

Effect of Tensile Stress on Growth of Self-Organized Nanostructures on Anodized Aluminum

The effect of an applied tensile stress on the pore ordering during anodization of aluminum was studied. A regular arrangement of nanopores was observed at a relatively low external tensile stress. On the contrary, a high tensile stress completely destroys the pore arrangement on anodized surfaces. Under such conditions, huge holes and pits are formed on the surface. The arrangement of nanopores on samples anodized under applied stresses was examined by Fourier transform analysis and Delaunay triangulation and compared with nonstressed samples. The ordering of pores was found to be dependent on the applied tensile stress. The percent of defects in the triangular lattice increases with increasing applied tensile stress. This result suggests that the surface stress has to be taken into account in a future modeling of the growth of porous oxide layer on anodized aluminum.

Performance of MAP Reconstruction for Hot Lesion Detection in Whole-Body PET/CT: An Evaluation With Human and Numerical Observers

For positron emission tomography (PET) imaging, different reconstruction methods can be applied, including maximum likelihood (ML ) and maximum a posteriori (MAP) reconstruction. Postsmoothed ML images have approximately position and object independent spatial resolution, which is advantageous for (semi-) quantitative analysis. However, the complex object dependent smoothing obtained with MAP might yield improved noise characteristics, beneficial for lesion detection. In this contribution, MAP and postsmoothed ML are compared for hot spot detection by human observers and by the channelized Hotelling observer (CHO). The study design was based on the ldquomultiple alternative forced choicerdquo approach. For the MAP reconstruction, the relative difference prior was used. For postsmoothed ML, a Gaussian smoothing kernel was used. Both the human observers and the CHO performed slightly better on MAP images than on postsmoothed ML images. The average CHO performance was similar to the best human performance. The CHO was then applied to evaluate the performance of priors with reduced penalty for large differences. For these priors, a poorer detection performance was obtained.

FDG positron emission tomographic scintigraphy can reveal Castleman's disease as a cause of inflammation.

Asymptomatic patients with increased inflammatory findings pose a challenge to the clinician. As in patients with fever of unknown origin (FUO), these patients frequently undergo Ga-67 scintigraphy to localize the inflammatory focus. Recently, F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) has proved its clinical value in FUO. When FUO or inflammation is a result of large-vessel vasculitis, FDG-PET scintigraphy is clearly superior to Ga-67 scintigraphy. The authors report the abdominal localization by FDG-PET scan of Castiemans disease as a cause of inflammatory blood findings in an asymptomatic 33-year-old woman. Castiemans disease is a rare lymphoproliferative disorder with high interleukin-6 production and is possibly caused by human herpes virus type 8. Use of FDG-PET scanning should no longer be restricted to the work-up of neoplasms and should be included in cases of inflammatory conditions.