Positron Emission Tomography in Lymphoma: Comparison with Computed Tomography and Gallium-67 Single Photon Emission Computed Tomography

With the advent of positron emission tomography (PET), metabolic imaging has become a reality for tumor staging and monitoring response to therapy in lymphoma. Increased Fluorine-18 fluorodeoxyglucose ([¹⁸F]FDG) uptake in lymphomas has been well documented in the literature; it is based upon elevated glycolysis and longer residence time of FDG in malignant cells compared to most normal tissues. This suggests that in tumor staging, FDG-PET may be more sensitive and specific than the anatomic imaging modalities. Computed tomography (CT) is the standard imaging modality for the staging and restaging of lymphoma, and Gallium-67 (⁶⁷Ga) scintigraphy has played an important role in monitoring response to therapy and follow-up of patients. Published results suggest that FDG-PET is superior to ⁶⁷Ga imaging and may be equal or superior to CT for the detection of nodal as well as extranodal involvement in lymphoma.     

Positron Emission Tomography in Urology

Positron Emission Tomography has rapidly become available in many institutes throughout Europe during the last years. Also the clinical indications for PET have increased in this period, especially in the field of oncology and based on FDG PET. In this review paper an overview on the principles and an update on the developments of PET is given. Emphasis on the spectrum of current and newly developed radiopharmaceuticals in particular the possibilities on targeted imaging is discussed. Next we provide a brief summary of the current literature on the clinical results of PET in oncological urology (prostate, bladder, kidney, testicular and penile cancer) and non-oncological urology (neuroimaging in bladder dysfunction).     

Computed Tomography in Radiotherapy Treatment Planning

Computed tomography (CT) provides in creased accuracy in tumour localisation, patient ouline data and heterogeneity information. This makes the use of CT highly desirable in 2–dimensional treatment planning. Where 3–dimensional (3–D) planning is used computed tomography (or possibly MRI) is essential. Radiotherapy departments must include dedicated CT scanners if they are to attain acceptable accuracy in simulation and treatment planning. The use of modern accelerators and treatment planning systems will be downgraded in the absence of routine CT imaging in a Radiotherapy Department.     

Computerized Tomography in Dural Sinus Thrombosis

Thirteen young patients with DST are presented. The average age was 31.3 years. Seven patients presented with severe headaches. Six patients appeared to have no apparent cause for their thromboses while predisposing factors (polycythaemia, malignancy, posttrauma), were present in three. One patient was in her 1st trimester of pregnancy. Four patients had DVT while 2 of these patients also had pulmonary embolism. There was one death. Six patients had full recovery and six had mild residual hemiparesis. The prognosis is therefore good in this group of young patients with DST. Treatment should be directed at the primary cause. Where no cause can be found, treatment is aimed at the presenting symptoms. The role of CT is stressed. The presence of abnormal areas of hemorrhage or infarctions especially if they are parasagittal and/or bilateral should alert the radiologist to the diagnosis of DST. The empty delta sign, the cord sign, the dense vein sign as well as the presence of transcerebral medullary veins are highly specific. CT is therefore not only noninvasive but highly accurate and is the imaging procedure of choice. There is no need for angiography except in a selected few and CT has already replaced angiography. The role of MRI needs to be studied. It is entirely noninvasive and may when it becomes freely available, replace CT. So far, only three cases have been reported in the English literature. Signal void is a characteristic of flowing blood and a throm-bosed venous channel will show a shortening of the T1 signals. In addition, the paramagnetic properties of deoxyhaemoglobin and methaemoglobin may allow determination of the age of the thrombus (Macchi et al 1986). However, at the present state of the art, CT remains the first radiological screening procedure (Braun et al 1985).     

Computerised Tomography of Keratoconus

This case report shows that computerised tomography can effectively illustrate kerato-conus. The diagnosis in a patient with visual failure, headaches and “papilloedema” became apparent on CT scanning. The CT scan appearance of keratoconus is described.     

Computed Tomography in Carcinoma of the Larynx

CT scanning in the investigation of carcinoma of the larynx is compared with direct laryngoscopy and laryngectomy specimens. Scans of twenty-two patients studied on a GE 8800 scanner over a two-year period are retrospectively reviewed. CT scanning compares closely with direct laryngoscopy in ability to define the longitudinal extent of tumours and is superior in evaluating the soft tissues deep to the mucosal surface and in identifying cervical lymphadeno-pathy. Our findings agree with previous reports and we conclude that CT scanning is an imaging modality complementary to direct laryngoscopy and uniquely useful in characterizing the extent of carcinoma of the larynx in areas vital to planning of appropriate therapy.     

High Resolution Computed Tomography in Stapedial Otosclerosis

The value of high-resolution CT scanning in diagnosing stapedial otosclerosis and in influencing surgical planning was studied. 40 cases, consisting of patients of both genders, above the age of 14 years, with a clinical diagnosis of otosclerosis underwent HRCT of the temporal bones. Images were acquired in axial plane, with a bone algorithm, keeping slice thickness at 0.5 mm and intervals of 0.5 mm. Reconstruction of the volume data set was done to obtain overlapping slices in various planes, so as to obtain the best possible images of the footplate of stapes. The thickness of the footplate was measured and the site of lesion was noted in these images. On exploratory tympanotomy, the footplate was assessed and graded according to a visual scale. HRCT was able to diagnose stapedial otosclerosis in 85% ears. It was able to identify the presence of a thickened footplate correctly with a sensitivity of 85.3% (P value 0.16). It was able to correctly localize the site of otosclerotic focus in 85% cases (P value <0.01). Thus, an estimate of the thickness of the footplate likely to be encountered and thus the amount of drilling likely to be required to create a fenestra; and the likely site of maximum thickness could be made pre-operatively. This study also established the value of multislice CT on the acquisition of such data. This method obviates the requirement of difficult patient positioning, reduces scanning time; while greatly improving the sensitivity of the scanning.     

Positron Emission Tomography/Computed Tomography and Biomarkers for Early Treatment Response Evaluation in Metastatic Colon Cancer

Background.

Treatment options for metastatic colon cancer (mCC) are widening. We prospectively evaluated serial 2-deoxy-2-[18F]fluoro-d-glucose positron-emission tomography/computed tomography (PET/CT) and measurements of tissue inhibitor of metalloproteinases-1 (TIMP-1), carcinoembryonic antigen (CEA), and liberated domain I of urokinase plasminogen activator receptor (uPAR(I)) for early assessment of treatment response in mCC patients.

Methods.

Thirty-three mCC patients scheduled for first-line chemotherapy with capecitabine and oxaliplatin (CAPOX) and bevacizumab participated; 27 were evaluated by PET/CT before treatment, after one and four treatment series. Morphological and metabolic response was independently assessed according to Response Evaluation Criteria in Solid Tumors and European Organization for Research and Treatment of Cancer PET criteria. Plasma TIMP-1, plasma uPAR(I), and serum CEA were determined.

Results.

Metabolic response after one treatment course predicted the ability of CAPOX and bevacizumab to induce morphological response after four treatment series with a sensitivity of 80%, specificity of 69%, and odds ratio of 13.9 (95% confidence interval [CI] 1.9; 182). Early metabolically stable or progressive disease was associated with shorter progression-free survival (hazard ratio [HR] = 3.2 [CI 1.3; 7.8]). Biomarker levels at early evaluation were associated with shorter OS (TIMP-1 per unit increase on a log-2-transformed ng/mL scale: HR = 2.6 [CI 1.4; 4.9]; uPAR(I) per 25 fmol/mL increase: HR = 1.5 [CI 1.1; 2.1]).

Conclusion.

This monocentric study demonstrated predictive value of early metabolic PET response and prognostic value of TIMP-1 and uPAR(I) levels in mCC treated with CAPOX and bevacizumab. Results support investigation of PET/CT, TIMP-1, and uPAR(I) guided early treatment adaptation in mCC.     

Positron Emission Tomography/Computed Tomography Predictors of Overall Survival in Stage IIIC/IV Ovarian Cancer

OBJECTIVE: To evaluate the role of 2-deoxy-2-(F)fluoro-D-glucose (FDG) positron emission tomography/computed tomography (PET/CT) for selecting patients with extensive ovarian cancer (OC) for neoadjuvant chemotherapy by evaluating predictors of overall survival in patients with stage IIIC/IV OC. MATERIALS AND METHODS: From September 1, 2004, to November 20, 2011, 514 consecutive patients with a pelvic tumor underwent preoperative PET/CT; 179 patients had stage IIIC/IV OC. Patients' characteristics were collected from 153 patients with stage IIIC/IV OC who underwent primary surgery. In 152 patients with stage IIIC/IV OC, clinical predictors and PET/CT predictors of survival were evaluated. RESULTS: Median age was 64 years (range, 38-88 years); 87% (113) of the 153 patients had a performance status of less than 2; 55% (84) of the 153 patients had PET/CT stage III, and 45% (69) of the 153 patients had PET/CT stage IV. Using univariate analysis, incomplete debulking (P = 0.0001), pleural exudates (P = 0.001), postmenopausal state (P = 0.01), WHO performance status greater than 2 (P = 0.01), PET/CT stage IV (P = 0.01), and large bowel mesentery implants (P = 0.02) were statistically significant prognostic variables. Using multivariate Cox regression analysis, incomplete debulking was the only statistically significant independent prognostic variable (P = 0.0001). Median overall survival was significantly longer in the 53 patients with no residual tumor than in the 99 patients with residual tumor (33.3 vs 25.5 months; P = 0.0001) CONCLUSION: Suggested PET/CT criteria for referral of patients with advanced OC to neoadjuvant chemotherapy are PET/CT stage IV, pleural exudates, and PET-positive large bowel mesentery implants. Evaluation of selection criteria for neoadjuvant chemotherapy should be promoted in prospective clinical trials, with survival as the primary end point.     

Computerised Tomography of the Pancreas

Computerized Tomography has been performed in 70 patients with suspected pancreatic disease, and our early experience has been reviewed. Our results appear to confirm that pancreatic lesions can be clearly shown in the majority of patients. Provided that the patients are selected carefully, it seems likely that Computerized Tomography will have an important role in the demonstration and diagnosis of pancreatic disease in the future.