Six versus eight doses of rituximab in patients with aggressive B cell lymphoma receiving six cycles of CHOP: results from the "Positron Emission Tomography-Guided Therapy of Aggressive Non-Hodgkin Lymphomas" (PETAL) trial.

Standard first-line treatment of aggressive B cell lymphoma comprises six or eight cycles of cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) plus eight doses of rituximab (R). Whether adding two doses of rituximab to six cycles of R-CHOP is of therapeutic benefit has not been systematically investigated. The Positron Emission Tomography-Guided Therapy of Aggressive Non-Hodgkin Lymphomas (PETAL) trial investigated the ability of [18F]-fluorodesoxyglucose PET scanning to guide treatment in aggressive non-Hodgkin lymphomas. Patients with B cell lymphomas and a negative interim scan received six cycles of R-CHOP with or without two extra doses of rituximab. For reasons related to trial design, only about a third underwent randomization between the two options. Combining randomized and non-randomized patients enabled subgroup analyses for diffuse large B cell lymphoma (DLBCL; n = 544), primary mediastinal B cell lymphoma (PMBCL; n = 37), and follicular lymphoma (FL) grade 3 (n = 35). With a median follow-up of 52 months, increasing the number of rituximab administrations failed to improve outcome. A non-significant trend for improved event-free survival was seen in DLBCL high-risk patients, as defined by the International Prognostic Index, while inferior survival was observed in female patients below the age of 60 years. Long-term outcome in PMBCL was excellent. Differences between FL grade 3a and FL grade 3b were not apparent. The results were confirmed in a Cox proportional hazard regression model and a propensity score matching analysis. In conclusion, adding two doses of rituximab to six cycles of R-CHOP did not improve outcome in patients with aggressive B cell lymphomas and a fast metabolic treatment response.

Skin cancer induced by natural UV-radiation as an occupational disease­requirements for its notification and recognition.

In Germany over 2.5 million employees have an increased risk of skin cancer due to their occupational exposure to natural UV-irradiation. The medical consultation board "Occupational diseases" of the Ministry of Labor and Social affairs has investigated the association between occupational UV-irradiation and skin cancer risk and recommends to add the following new occupational disease into the appendix1 of the German ordinance on occupational diseases: "Squamous cell carcinoma and multiple actinic keratosis due to natural UV-irradiation". In this article we report in the view of the German Society of Occupational and Environmental Dermatology (ABD) and the German Statutory accident insurance (DGUV), whose criteria have to be fulfilled for the notification and recognition of an occupational skin cancer due to natural UV-irradiation.

[Correlative imaging in cardiology. Principles and clinical application]. / Korrelative Bildgebung in der Kardiologie. Theoretische Ansätze und klinische Anwendung.

Technical progress has engendered a broad spectrum of methods to image cardiac structure, function, and metabolism. Frequently, the imaging tools available provide complementary information. Therefore, methods to integrate image information from different modalities into one common coordinate system are increasingly receiving attention also in cardiology. Currently available technology includes software-based image fusion as well as hardware-based registration of datasets. The latter capitalizes on so-called hybrid cameras combining detectors of different modalities in one gantry. Hardware-based image fusion is, to date, anatomically more accurate than the software-based methodology. However, the anatomic accuracy of both approaches is still far from perfect. This is, in particular, due to artifacts caused by respiratory movements also affecting the heart. The clinical potential of correlative imaging of the heart includes an improvement of accuracy in diagnosing hemodynamically significant coronary artery disease using single-photon emission computed tomography (SPECT). This is due to the possibility to correct myocardial scintigraphy for attenuation artifacts using registered X-ray computerized tomographic (CT) images. The visualization of coronary anatomy and myocardial perfusion in one imaging session using hybrid systems combining CT with positron emission tomography (PET) or SPECT is also an interesting option. Nevertheless, larger clinical trials investigating its usefulness are still missing. The possibility to match structure with radioactivity concentration is essential for approaches to image the molecular composition of atherosclerotic plaques and their stability.

SPECT-guided CT for evaluating foci of increased bone metabolism classified as indeterminate on SPECT in cancer patients.

UNLABELLED: Hybrid cameras combining SPECT and spiral CT offer the opportunity to obtain a diagnostic-quality CT image of scintigraphically suggestive lesions that directly correlates with the SPECT image. The field of view of the CT scan can be adapted on the basis of the SPECT findings ("SPECT-guided CT"). The aim of the present study was to investigate the value of SPECT-guided CT in the assessment of foci of increased bone metabolism classified as indeterminate on SPECT. METHODS: Of 272 consecutively examined patients with histologically confirmed malignancy who underwent bone scintigraphy, 112 (41%) required further workup by SPECT because a definite diagnosis could not be established using whole-body planar scintigraphy alone. In 57 of these patients, SPECT was accompanied by inline CT over the body region of interest; the remaining 55 subjects underwent only stand-alone SPECT for logistic reasons. The 57 SPECT/CT studies were retrospectively evaluated by readers who were unaware of the clinical pretest probability and the findings on the planar scans. In total, 52 lesions in 44 patients were rated as indeterminate on the SPECT images. Afterwards, the corresponding SPECT/CT images were analyzed and the findings previously rated as indeterminate were classified either as definitely benign, indeterminate, or definitely malignant. RESULTS: Of the 52 indeterminate findings on SPECT, 33 (63%) could be correlated with benign findings on CT. These findings involved mostly osteochondrosis, spondylosis, and spondylarthrosis of the spine. Fifteen lesions (29%) could be correlated with osteolysis or sclerotic metastases on CT. Even after analysis of the SPECT/CT images, 4 lesions (8%) remained indeterminate. These lesions were in the ribs and the scapula. CONCLUSION: SPECT-guided CT was able to clarify more than 90% of SPECT findings classified as indeterminate in an analysis that was masked as to clinical pretest probability and the planar scan findings. Further studies carefully addressing the cost efficiency of this new technology and its actual clinical value are encouraged by this observation.

Anatomical accuracy of hybrid SPECT/spiral CT in the lower spine.

AIM: The anatomical accuracy of hardware-based registration of skeletal single photon emission computed tomography (SPECT) and X-ray computerized tomography (CT) has as yet not been studied. The aim of this study was to evaluate this variable in the lower spine for a newly introduced hybrid SPECT/spiral-CT camera. METHODS: In 22 patients referred for degenerative joint disease or tumours, whole-body bone scintigraphy including hybrid SPECT/spiral CT of the lower spine was performed. Subsequent analyses were performed on these pairs of images as well as on data sets obtained after using a rigid automated fusion procedure in addition. Two observers independently measured the distances between the visually determined centres of gravity of the CT and SPECT representation of the fourth and fifth lumbar vertebral body in the X-, Y- and Z-directions (X-, Y- and Z-distances). RESULTS: The distances determined by the two observers for the two vertebral bodies correlated significantly and were averaged for further analysis. For hybrid SPECT/spiral CT without consecutive automated registration, the mean X-, Y- and Z-distances were 1.6+/-1.9 mm, 1.7+/-1.3 mm and 0.9+/-0.5 mm, respectively. Additional automated registration lowered these values to 1.2+/-0.9 mm, 1.1+/-0.7 mm and 0.8+/-0.4 mm, respectively. The difference for the Y-distance proved statistically significant (P<0.05). Additional automated registration significantly reduced the number of subjects in whom at least one of the distances determined was greater than the SPECT pixel size of 4.6 mm from 14% (n=3) to 0% (P<0.05). CONCLUSION: Hardware-based fusion between skeletal SPECT and CT offers a nearly perfect data match in the lower spine. The additional use of a tool for automated rigid registration has the potential to reduce the error of alignment even further and may be useful in patients with reduced compliance leading to movements between the two examinations.

Isotropic reconstruction of SPECT data using OSEM3D: correlation with CT.

RATIONALE AND OBJECTIVES: A statistical based iterative single-photon emission-computed tomography (SPECT) reconstruction algorithm (OSEM) modeling the depth-dependent collimator response in three dimensions has recently been introduced (OSEM3D). The aim of this study was to evaluate the axial shape fidelity of OSEM3D in comparison to OSEM, not taking this variable into account (OSEM2D). MATERIALS AND METHODS: SPECT and separate spiral CT were performed in a phantom containing spheres filled with In-111. In-111-pentetreotide-SPECT and separate spiral-CT imaging were also performed in 22 patients with neuroendocrine tumors. Using window settings adapting the transversal size of the SPECT hot spots to that on CT and the 50% isocontour as boundary, the three-dimensional extensions (dx, dy, dz) of the SPECT representation of the structures under study were measured. These variables were also determined for CT. Furthermore, an index of eccentricity was calculated by averaging the ratios between dz and dx and dz and dy (IE). For isotropically imaged spheres, IE is 1. RESULTS: For OSEM2D, IE was significantly different from 1 in the phantom data (P < .05); this was not the case for OSEM3D and CT. This finding was accounted for by a significantly greater dz on the OSEM2D-SPECT images. In the patient data, dz was by approximately 15.5% greater for OSEM2D than for the other two modalities (P < .05). CONCLUSIONS: The use of OSEM3D avoids deformation of hot SPECT lesions in z-direction. This may be of particular importance in SPECT/CT hybrid imaging capitalizing on the exact match of both modalities.

SPECT/Spiral-CT hybrid imaging in unclear foci of increased bone metabolism: a case report.

In bone scintigraphy, the differentiation between degenerative processes and bone metastases is still difficult. Therefore, additional radiological studies are regularly needed after bone scintigraphy. The now introduced hybrid-cameras combining single-photon emission computed tomography (SPECT) and spiral-CT are unique in the sense that they offer the opportunity to correlate the functional information with morphology in one session. We herein present two patients in whom this technological setup allowed a definite diagnosis in scintigraphically unclear vertebral lesions. In a patient with breast cancer, hypermetabolic lesions were clearly correlated with osteolyses. In another patient with synovial carcinoma, spondylosis and spondylarthrosis caused focal tracer uptake in the lumbar spine. In addition to an improved diagnostic accuracy, SPECT/Spiral-CT will considerably abbreviate the diagnostic process.

Single-detector helical CT in PET-CT: assessment of image quality.

OBJECTIVE: CT in positron emission tomography (PET)-CT imaging is often performed as a single scan from the base of the skull to the groin, potentially resulting in degradation of the quality of CT scans depending on the position of the patient's arms and mode of breathing and the use and timing of IV contrast injection. The aim of our study was to assess the impact of artifacts on the diagnostic quality of CT scans using a single-detector helical CT scanner in PET-CT imaging. MATERIALS AND METHODS: Two radiologists retrospectively evaluated the diagnostic image quality of CT scans obtained with PET-CT in 81 patients with lymphoma. The severity of the artifacts related to the position of the patient's arms beside the body, the influence of breathing motion, and the presence of contrast material in the upper thoracic veins were ranked using a 4-point scale. RESULTS: Performing CT with the patient's arms positioned beside the body resulted in streak artifacts, predominantly in the upper abdomen, that were graded as mild in 22%, moderate in 40%, and severe in 38% of the scans. A patient's weight significantly correlated with the degree of severity of the artifacts (p < 0.05). Shallow breathing by the patient during scanning caused blurring and double-imaging, again predominantly in the upper abdomen, that were graded as mild in 23%, moderate in 49%, or severe in 28% of the scans. In 84% of the CT scans obtained with IV contrast material, the image quality of the upper thoracic region was moderately (27%) or severely (57%) degraded by streak artifacts from highly concentrated contrast material in the upper thoracic veins. CONCLUSION: The use of a single-detector CT scanner in whole-body PET-CT decreases the image quality of CT scans because of streak artifacts that occur predominantly in scans of the upper abdomen. Scanning with the patient's arms raised eliminates the streak artifacts in scans of the abdominal region. With the new generation of PET-CT devices equipped with MDCT scanners, breathing motion artifacts can be expected to be eliminated if protocols for breath-hold CT are applied. Reversing the direction of CT scanning allows one to avoid imaging the thoracic region at a time when undiluted IV contrast material is still present in the upper thoracic veins.

Positron Emission Tomography in Diagnosis and Therapy Monitoring of Patients with Lymphoma.

In contrast to conventional imaging modalities, positron emission tomography using fluorodeoxyglucose detects malignant tumors by their increased glucose metabolism. In patients with Hodgkin's disease or non-Hodgkin's lymphoma, FDG-PET imaging has been shown to sensitively identify enhanced tracer uptake in involved lymph nodes and infiltrated tissue. This brief review will summarize the currently available information on staging of lymphoma patients in comparison with other imaging modalities. In addition, FDG PET imaging has been suggested for differentiation of viable residual or recurrent tumor and scar after tumor therapy. One of the most promising applications of PET in the future will be the metabolic evaluation of early response to tumor therapy. It is hypothesized that changes in tumor metabolism occur before significant decrease of tumor mass. Early assessment of chemotherapy might help to avoid the toxicity of an ineffective therapy. In summary, the results concerning various clinical applications of PET imaging are encouraging for further prospective trials to document the advantage of PET in diagnosis and therapy of lymphoma patients as compared to conventional strategies.