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Objective: To evaluate the impact of 18F-fluoro-deoxy-glucose positron emission tomography after standard diagnostic workup in patients with advanced head and neck squamous cell carcinoma on staging and radiation treatment planning. Study Design: Prospective controlled study. Methods: Forty-eight patients (42 men and 6 women; mean age, 61 y; age range, 35-85 y) with histologically confirmed, advanced-stage (any T, N> or =N2 or T> or =T3, any N) mucosal head and neck squamous cell carcinoma underwent positron emission tomography. The routine workup consisting of physical examination, panendoscopy, chest x-ray film, and contrast-enhanced high-resolution helical computed tomography scan (HRCT) was used for comparison. End points were the extent of lymph node disease, distant metastases, and second primary tumors. Results: In 41 of 48 patients (85%) the lymph node findings between HRCT and positron emission tomography were concordant. In three patients positron emission tomography led to an upstaging of the tumor in its N category, and in four patients positron emission tomography underestimated lymph node involvement. Positron emission tomography revealed more difficulties in delineating lymph node metastases adjacent to the primary tumor than did HRCT, but was superior for the detection of distant and contralateral lymph node metastases. Positron emission tomography suggested distant metastatic lesions in 6 of 48 patients (13%). Cytological workup confirmed distant metastases in two (4%) and second primary tumors in another two patients (4%). Positron emission tomography results were false-positive in two (4%) patients because of inflammatory changes. Conclusions: Whole-body PET is able to assess lymph node involvement, distant metastases, and second primaries in a single study. Even after a routine clinical staging, positron emission tomography leads to a change of treatment in approximately 8% of patients. [ABSTRACT FROM AUTHOR]

Objectives/hypothesis: To evaluate imaging findings using positron emission tomography (PET) and 18F-fluorodeoxyglucose (FDG) in mucosal malignant melanoma (MMM) of the head and neck. Study Design: Retrospective evaluation. Methods: Eighteen PET examinations were performed for initial staging and/or follow-up in 10 patients with MMM. Medical records of 6 male and 4 female patients (age range, 43--81 y; mean, 67 y) were reviewed retrospectively with regard to the patients' history, symptoms, and clinical course. Primary melanoma elsewhere in the body was excluded at the time of diagnosis. Results: All MMM were visible in staging PET examinations, but FDG uptake depended on lesion size and anatomic site. Big lesions with a nodular growth, as seen in pathologic specimens, were better visible compared with lesions with a more superficial spread within the mucous membranes. Lesions in the anterior part of the nasal cavity were more difficult to detect than those in the posterior sinonasal complex because of possible interference with nonspecific uptake in muscles of the mouth and pronounced appearance of the skin when imaging was performed using filtered back projection without attenuation correction. Conclusion: We found that MMM of the head and neck can be visualized using FDG PET. Furthermore, locoregional and distant metastases can be evaluated much like those of cutaneous malignant melanoma. Therefore, PET may be suitable for the staging and/or restaging of these patients. Further studies have to elucidate the potential role of FDG PET in patient management. [ABSTRACT FROM AUTHOR]

Background: Previous studies have shown that application of relatively low 131 I-Iodine activities can successfully be used to treat patients with Graves' disease (GD). We assessed treatment outcome in the long-term follow-up of our GD patients and influencing factors., Methods: We evaluated 521 GD patients in this retrospective clinical single-center study. In all patients we performed scintigraphy and thyroid uptake measurement after 4 and 24 hours using 10 MBq 123 I and calculated administered activity using Marinellis' formula. Treatment was done according to national regulations. Minimal routine clinical evaluation of all patients was available after 6 weeks and after 3, 6 and 12 months. Success of treatment was defined as euthyroid state or hypothyroidism 6 months after therapy., Results: We usually applied relatively low 131 I activities. Three hundred seven patients (58.9%) became hypothyroid within 21 years of follow-up. One hundred thirty-nine patients (26.7%) became euthyroid and stayed euthyroid until the end of follow-up. We found a plateau after 7 years of initial therapy with only a few patients becoming hypothyroid after that time and identified 75 patients (14.4%) with persistent hyperthyroidism or recurrence., Conclusions: Treatment with relatively low 131 I activities produce favorable responses as shown in previous works. We found a high proportion of patients with long-term euthyroid state. Application of low activities reduces radiation burden of patients and, depending on radiation protection legislation, may lead to shortened hospital stay and reduced costs. Therefore, we feel that application of higher activities to treat GD patients as recommended in several current guidelines should be reconsidered.

Objectives: To compare pain relief after CT-guided lumbar epidural steroid injections (ESI) using particulate (triamcinolone) and non-particulate (dexamethasone) steroids, and to explore factors affecting the effectiveness of both steroid types., Methods: This retrospective observational study included 806 patients with lumbar radiculopathy and corresponding MRI or CT abnormalities of the lumbar spine, who were matched using the propensity score method, yielding two cohorts of 209 patients each. Pain intensity was evaluated prior to the procedure using a pain numerical rating scale (NRS) with range 0-10. Reevaluation took place 1 day and 4 weeks post-injection. Logistic regression analysis and cubic splines applied to generalized additive models were implemented to assess the differences in pain reduction after ESI in the analyzed patient groups., Results: Four weeks post-injection, the overall chance of ≥ 50% pain reduction was lower in the dexamethasone group than that in the triamcinolone group (odds ratio [OR] = 0.55; p < 0.012). In the dexamethasone cohort, the intensity of baseline pain and the presence of a herniated intervertebral disc in the infiltrated segment were both significant and independent predictors of ≥ 50% pain relief. Patients with baseline NRS score ≥ 7 points had markedly less chance of ≥ 50% pain relief than patients with NRS score < 7 (OR = 0.53; p < 0.032), whereas disc herniation increased the chances more than twofold (OR = 2.29; p < 0.044). There was no significant correlation between the effectiveness of triamcinolone and any analyzed concomitant variables., Conclusions: Triamcinolone was superior for lumbar radiculopathy of severe intensity. For mild to moderate pain, no benefit of using triamcinolone over dexamethasone was found. The effectiveness of dexamethasone was lower for stenotic spinal lesions than for disc herniation., Key Points: • Triamcinolone is superior to dexamethasone for epidural treatment of severe lumbar radiculopathy. • For mild to moderate pain, dexamethasone could be equally effective. • Dexamethasone reduces pain caused by disc herniation much better than it does to pain caused by fixed stenotic spinal lesions.

Objectives: To compare the impact of unenhanced and contrast-enhanced multi-detector computed tomography (MDCT) for the detection of urinary stones and urinary obstruction in patients with suspected renal colic., Methods: 95 patients with suspected renal colic underwent a three-phase MDCT for evaluation of the urinary tract. The unenhanced scan and the multiphase examination were reviewed retrospectively by two radiologists for the characterization of urinary stones and signs of obstruction. Results of unenhanced MDCT were compared with those obtained during the second review of the entire multiphase examination., Results: Overall diagnosis of urinary stones revealed an accuracy of 97.0% for unenhanced, and 98.9% for multiphase MDCT with a significant difference between both protocols (mixed-effects logistic regression: odds ratio 3.3; p=0.019). With 3 versus 15 false positive ratings, multiphase MDCT was superior to unenhanced MDCT for the diagnosis of urinary stones. There was no significant difference in detecting signs of obstruction. Inter-reader agreement for overall stone detection was excellent on both unenhanced (kappa 0.84) and multiphase (kappa 0.88) MDCT., Conclusion: Contrast-enhanced multiphase MDCT offers distinct advantages compared to an unenhanced approach for the assessment of urinary stone disease, and therefore should be considered as a complementary examination for patients with inconclusive findings., (Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.)

Background: A spontaneous pneumothorax appears to be rarely seen in patients with an azygos lobe, although this normal variant is incidentally found on CT and chest X-ray. The displacement of the azygos vein from the azygos lobe to the paramediastinal position indicates previous pneumothorax., Methods: We report two patients (a 59 and a 27-year-old female) where the finding of an azygos lobe without an azygos vein proved to be a sign of previous iatrogenic pneumothorax., Conclusions: Documentation of an azygos lobe without azygos vein is highly suggestive of a previous pneumothorax. This observation may indicate an iatrogenic cause, because of the possible protective effect of an azygos lobe to the occurrence of spontaneous pneumothorax.

This retrospective study aimed to describe the differences between image readings done with combined positron emission tomography/computed tomography (PET/CT) and PET read together with contrast-enhanced CT (ceCT) in patients with squamous cell carcinoma of the head and neck. In 46 patients, no differences were found between the two readings for assessing infiltration of adjacent structures (P=.63), transgression of the midline (P=.67), lymph node involvement (P=.32), and T- and N stage. PET/CT and PET read together with ceCT have comparable diagnostic yield.

Aims: To prospectively investigate the diagnostic accuracy of dual-source computed tomography coronary angiography (CTCA) to diagnose coronary stenoses in relation to body mass index (BMI), Agatston score (AS), and heart rate (HR) as compared with catheter coronary angiography (CCA)., Methods and Results: Hundred and fifty consecutive patients (47 female, mean age 62.9 +/- 12.1 years) underwent dual-source CTCA without HR control. Patients were divided into subgroups depending on the median of their BMI (26.0 kg/m2), AS (194), and HR (66 b.p.m.). CCA was considered the standard of reference. Mean BMI was 26.5 +/- 4.2 kg/m2 (range 18.3-39.1 kg/m2), mean AS was 309 +/- 408 (range 0-4387), and HR was 68.5 +/- 12.6 b.p.m. (range 35-102 b.p.m.). Diagnostic image quality was found in 98.1% of all segments (2020/2059). Considering not-evaluative segments at CTCA as false-positive, overall per-patient sensitivity, specificity, positive, and negative predictive value were 96.6%, 86.8%, 82.6%, and 97.5%, respectively. High HR did not deteriorate diagnostic accuracy of CTCA. High BMI and AS were associated with a decrease in per-patient specificity to 84.1% and 77.8%, respectively, while sensitivity and negative predictive value remained high., Conclusion: Dual-source CTCA provides high diagnostic accuracy irrespective of the HR and serves as a modality to rule-out coronary artery stenoses even in patients with high BMI and AS.

Aim: The aim of this study was to assess the frequency of indeterminate (18)F-fluorodeoxyglucose (FDG) accumulations on positron emission tomography (PET) and PET/computed tomography (CT) images in patients with pelvic pathologies., Methods: We retrospectively evaluated 536 focal FDG accumulations of 166 PET/CT examinations. A consensus reading of PET/CT images, clinical data, and other imaging tests was the standard of reference to assess sensitivities and specificities of PET and PET/CT. Frequencies of indeterminate findings and intraobserver agreement were evaluated., Conclusion: PET/CT improves the anatomic delineation and the correct assignment of physiologic and pathologic uptake.

Purpose: To define the best threshold for tumor volume delineation of the (18) fluoro-2-deoxy-glucose positron emission tomography ((18)FDG-PET) signal for radiotherapy treatment planning of intensity-modulated radiotherapy (IMRT) in head and neck cancer., Methods and Materials: In 25 patients with head-and-neck cancer, CT-based gross tumor volume (GTV(CT)) was delineated. After PET-CT image fusion, window level (L) was adapted to best fit the GTV(CT), and GTV(PET) was delineated. Tumor maximum (S) and background uptake (B) were measured, and the threshold of the background-subtracted tumor maximum uptake (THR) was used for PET signal segmentation. Gross tumor volumes were expanded to planning target volumes (PTVs) and analyzed., Results: The mean value of S was 40 kBq/mL, S/B ratio was 16, and THR was 26%. The THR correlated with S (r = -0.752), but no correlation between THR and the S/B ratio was seen (r = -0.382). In 77% of cases, S was >30 kBq/mL, and in 23% it was 30% +/- 1.6% kBq/mL and 40% in tumors with S

This study assessed the ability of quantitative ultrasound (QUS) and digital X-ray radiogrammetry (DXR) to identify osteopenia and osteoporosis in patients with knee osteoarthritis (OA). One hundred and sixty-one patients with painful knee OA (81 men, 80 women; age 62.6+/-9.2 years, range 40-82 years) were included in this cross-sectional study and underwent dual-energy X-ray absorptiometry (DXA) of both hips and the lumbar spine, QUS of the phalanges and calcanei of both hands and heels, and DXR using radiographs of both hands. Unpaired t-test, Mann-Whitney U test, ROC analysis and Spearman's rank correlation were used for comparisons and correlation of methods. Using DXA as the reference standard, we defined a low bone mineral density (BMD) as a T-score < or =-1.0 at the lumbar spine or proximal femur. In contrast to phalangeal or calcaneal QUS, DXR was able to discriminate patients with a low BMD at the lumbar spine (p<0.0001) or hips (p<0.0001). ROC analysis showed that DXR had an acceptable predictive power in identifying OA patients a low hip BMD (sensitivity 70%, specificity 71%). Therefore, DXR used as a screening tool could help in identifying patients with knee OA for DXA.

Objective: In a phase I/II clinical study, we investigated tumor targeting in patients with head and neck squamous cell carcinomas (SCC), using an antibody directed against the extra-domain-B of fibronectin (EDB), a marker of angiogenesis and tissue remodeling., Study Design and Setting: Five patients with SCC were injected with the 123-iodine-radiolabeled L19(scFv)2 antibody and underwent scintigraphic detection with single photon emission tomography with computerized tomography (SPECT/CT). In addition, 18F-fluorodeoxyglucose (18FDG) positron emission tomography with computerized tomography (PET/CT) was performed., Results: Successful targeting of the primary tumor could be achieved in 4 of 5 patients and was comparable to PET imaging. No side effects were observed., Conclusions: Tumor targeting with the L19(scFv)2 antibody is also feasible for head and neck SCC., Significance: These results may serve as a base for future therapeutical applications in human beings, with modified versions of the L19(scFv)2 antibody, designed to selectively deliver bioactive molecules into malignant tumors.

In patients with a neck metastasis from an unknown primary with non-squamous cell cancer (non-SCC) histology, the primary is often located outside the head and neck area. We retrospectively evaluated 326 patient records and found 14 patients with non-SCC neck lymph node metastasis from an unknown primary undergoing whole body F-18-fluorodeoxyglucose (FDG) positron emission tomography (PET) with or without coregistered computed tomography (PET/CT). The PET or PET/CT findings were verified by pathological work-up, additional imaging tests, and clinical follow-up. PET detected pathological FDG uptake suspicious for the primary in eight patients. PET or PET/CT findings were true positive in seven patients, true negative in 4, false positive in 1, and false negative in two patients. In one patient PET/CT revealed a synchronous ovarian carcinoma. The results suggest that whole body imaging with FDG PET and PET/CT can be useful to identify unknown primaries of non-SCC origin. However, the work-up of patients undergoing PET or PET/CT in our study was very heterogeneous and the primary was more likely found in patients without extensive imaging before PET scanning. Further studies should evaluate if the histology of a neck nodal metastasis should influence the choice of the imaging method and the role of PET and PET/CT imaging for the work up of patients with a non-SCC neck lymph node metastasis of an unknown primary.

Unlabelled: PURPOSE OF REPORT: F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) can be used to image synovitis in patients with rheumatoid arthritis (RA). The aim of this study was to evaluate if a simple scoring system based on visual assessment of FDG joint uptake correlates with the clinical assessment of patients with RA undergoing antiinflammatory treatment., Materials and Methods: Seven patients with active RA underwent whole-body FDG PET and clinical assessment before and after treatment with the antitumor necrosis factor alpha antibody (infliximab). A PET total joint score, ie, the sum of all scores based on FDG uptake intensity between zero and 4 in 28 joints, was correlated with a total joint score based on the clinical disease activity in the same joints using a Spearman rank correlation., Results: The PET based total joint score was similarly high before onset as was the clinical total joint score. The decrease of FDG joint uptake in the follow-up PET scans correlated significantly with the clinical assessment. Additionally, synovial FDG uptake was found in extraarticular sites such as tendon sheaths and bursae., Conclusions: Visual assessment of FDG uptake shows a significant correlation with clinical evaluation of disease activity in patients with RA undergoing antiinflammatory treatment.

Background: Contrast-enhanced computed tomography (CT) and magnetic resonance imaging (MRI) are the standard imaging techniques to evaluate patients with carcinoma in the sinus/nasal area and orbit. The use of positron emission tomography (PET) with (18)F-fluorodeoxyglucose (FDG) in such patients is as yet less well established., Purpose: The aim of this study was to assess the clinical impact of PET co-registered with CT (PET/CT)., Patients: Evaluation of 21 consecutive patients., Methods: A retrospective analysis of the whole body PET/CT studies was done. Images were assessed visually without knowing the results of the other imaging technique. Histology and clinical follow-up served to verify lesions. The clinical impact on therapy was assessed together with the physician in charge., Results: All patients underwent PET/CT and CT or MRI for staging (n=9 scans) and restaging (n=17 scans) without treatment between the examinations. PET/CT changed the treatment protocol in 2 patients at staging and in 7 at re-staging. Distant metastases were found in 5 and a secondary tumour in 1 patient., Conclusions: Whole body PET/CT adds clinically important information to CT or MRI, thus, influencing treatment.

Osteoarthritis (OA) of the knee is common in the aging population. In patients with OA, bone mineral density (BMD) is usually increased, but the fracture rate does not appear to be systematically lower than in age-matched healthy controls. The aim of our study was to describe hip BMD in patients presenting with unilateral symptomatic knee OA. Patients with painful knee OA were prospectively included in a single-center, randomized, double-blind, placebo-controlled clinical trial to evaluate the structure-modifying efficacy of an oral chondroitin sulfate treatment on the knee joint. The majority of these patients underwent additional measurements of BMD of their lumbar spine and both hips using dual-energy X-ray absorptiometry (DXA). The hip BMD values of the leg with symptomatic knee OA were compared with the contralateral hip. One-hundred and sixty-one patients (81 men and 80 women; aged 62.6 +/- 9.2 yr, range 40-82 yr) underwent DXA. The median total hip BMD was higher than in age-matched controls, but patients had a relatively lower hip BMD in the knee OA-affected leg (p = 0.001). Our knee OA patients rarely presented with concomitant osteoporosis, but usually had a relatively lower hip BMD on the affected leg. Therefore, we suggest that the hip of the leg with symptomatic knee OA should be measured if DXA is acquired only at one hip. Future studies have to assess whether the relative decrease of BMD at the hip of the leg with knee OA might influence fracture incidence.

Purpose: To prospectively compare the accuracy of helical contrast material-enhanced computed tomography (CT) with that of CT and positron emission tomography (PET) combined and CT and single photon emission CT (SPECT) combined in the detection of bone invasion in patients scheduled to undergo surgery for clinically suspected oral cavity carcinoma with possible bone invasion, with surgical results as the reference standard., Materials and Methods: This study had local ethical committee approval, and all patients gave written informed consent. Thirty-four consecutive patients (17 men, 17 women; mean age, 64.2 years; age range, 46.0-84.6 years) who were clinically suspected of having bone invasion from oral cavity carcinoma prospectively underwent helical contrast-enhanced CT, coregistered PET/CT, and coregistered SPECT/CT. Two radiologists assessed the contrast-enhanced CT images and two nuclear medicine physicians separately assessed the PET/CT and SPECT/CT images in consensus and without knowledge of the results of other imaging tests. The presence of bone involvement as suggested with an imaging modality was compared with histologic findings in the surgical specimen., Results: With histologic findings as the standard of reference, the accuracy of SPECT/CT (88% [30 of 34 patients]) was lower than that of PET/CT and contrast-enhanced CT (94% [32 of 34 patients] and 97% [33 of 34 patients], respectively). Sensitivity was highest with PET/CT (100% [12 of 12 patients]), and specificity was highest with contrast-enhanced CT (100% [22 of 22 patients]). Fluorine 18 fluorodeoxyglucose (FDG) uptake seen on two sides of the same cortical bone was not a helpful imaging pattern for better identifying bone invasion in patients without evident cortical erosion on CT scans., Conclusion: The assessment of cortical erosion with contrast-enhanced CT and the CT information from PET/CT are the most reliable methods for detecting bone invasion in patients with oral cavity carcinoma. FDG uptake seen on PET/CT images does not improve identification of bone infiltration., (RSNA, 2005)

Objective: We sought to determine the impact of positron emission tomography/computed tomography (PET/CT) on the management of presumed resectable pancreatic cancer and to assess the cost of this new staging procedure., Summary Background Data: PET using 18F-fluorodeoxyglucose (FDG) is increasingly used for the staging of pancreatic cancer, but anatomic information is limited. Integrated PET/CT enables optimal anatomic delineation of PET findings and identification of FDG-negative lesions on computed tomography (CT) images and might improve preoperative staging., Material and Methods: Patients with suspected pancreatic cancer who had a PET/CT between June 2001 to April 2004 were entered into a prospective database. Routine staging included abdominal CT, chest x-ray, and CA 19-9 measurement. FDG-PET/CT was conducted according to a standardized protocol, and findings were confirmed by histology. Cost benefit analysis was performed based on charged cost of PET/CT and pancreatic resection and included the time frame of staging and surgery., Results: Fifty-nine patients with a median age of 61 years (range, 40-80 years) were included in this analysis. Fifty-one patients had lesions in the head and 8 in the tail of the pancreas. The positive and negative predictive values for pancreatic cancer were 91% and 64%, respectively. PET/CT detected additional distant metastases in 5 and synchronous rectal cancer in 2 patients. PET/CT findings changed the management in 16% of patients with pancreatic cancer deemed resectable after routine staging (P = 0.031) and was cost saving., Conclusions: PET/CT represents an important staging procedure prior to pancreatic resection for cancer, since it significantly improves patient selection and is cost-effective.

Institutional review board approval and written informed consent were obtained. Patients with newly diagnosed prostate cancer and patients suspected of having recurrent prostate cancer were prospectively evaluated with fluorine 18 fluorocholine (FCH) combined in-line positron emission tomography (PET) and computed tomography (CT). In 19 patients (mean age, 67 years +/- 8; range, 57-85 years), standardized uptake values of FCH in 17 different tissues were determined by using volumes of interest. In nine patients evaluated at initial staging, histologic findings of the resected prostate were compared to FCH uptake. Only small variations of physiologic tracer accumulation were measured in all organs but the kidneys. Differentiation of benign hyperplasia from cancerous prostate lesions was not possible with FCH PET/CT. However, in patients with recurrent prostate cancer, FCH PET/CT is a promising imaging modality for detecting local recurrence and lymph node metastases., ((c) RSNA, 2005.)

Purpose: Gastrointestinal stromal tumours (GIST) are mesenchymal neoplasms of the gastrointestinal tract that are unresponsive to standard sarcoma chemotherapy. Imaging of GIST patients is done with structural and functional methods such as contrast-enhanced helical computed tomography (ceCT) and positron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG). The aim of this study was to compare the prognostic power of PET and ceCT and to evaluate the clinical role of PET/CT imaging., Methods: All patients with GIST undergoing PET or PET/CT examinations were prospectively included in this study, and the median overall survival, time to progression and treatment duration were documented. The prognostic significance of PET and ceCT criteria of treatment response was assessed and PET/CT was compared with PET and ceCT imaging. Data for 34 patients (19 male, 15 female, 21-76 years) undergoing PET or PET/CT for staging or restaging were analysed., Results: In 28 patients, PET/CT and ceCT were available after introduction of treatment with the tyrosine kinase inhibitor imatinib mesylate (Gleevec; Novartis, Basel, Switzerland). Patients without FDG uptake after the start of treatment had a better prognosis than patients with residual activity. In contrast, ceCT criteria provided insufficient prognostic power. However, more lesions were found on ceCT images than on PET images, and FDG uptake was sometimes very variable. PET/CT delineated active lesions better than did the combination of PET and ceCT imaging., Conclusion: Both PET and PET/CT provide important prognostic information and have an impact on clinical decision-making in GIST patients. PET/CT precisely delineates lesions and thus allows for the correct planning of surgical interventions.

Purpose: To retrospectively compare diagnostic value of coregistered fluorine 18 fluorodeoxyglucose positron emission tomographic (PET) and computed tomographic (CT) scans obtained with low-dose nonenhanced CT (PET/CT) with those routinely obtained with contrast material-enhanced CT for staging and restaging of disease in patients with Hodgkin disease or high-grade non-Hodgkin lymphoma., Materials and Methods: Sixty patients (mean age, 39.6 years +/- 17.1 [standard deviation]) with Hodgkin disease (n = 42) or high-grade non-Hodgkin lymphoma (n = 18) were included in this retrospective study. All patients underwent PET/CT and contrast-enhanced CT within a maximum of 24 days (mean, 9.1 days +/- 7.0) of each other for staging (n = 19) or first follow-up examination (n = 41). Findings were extracted from original written reports (PET/CT, contrast-enhanced CT) and compared with findings of reference standard, which included biopsy or follow-up with clinical, laboratory, or other imaging findings. For statistical analysis, sensitivity and specificity were calculated with findings of the reference standard. Agreement of both methods was determined with Cohen kappa and McNemar tests on a per-patient basis., Results: For evaluation of lymph node involvement, sensitivity of PET/CT and contrast-enhanced CT was 94% and 88%, and specificity was 100% and 86%, respectively. For evaluation of organ involvement, sensitivity of PET/CT and contrast-enhanced CT was 88% and 50%, and specificity was 100% and 90%, respectively. Agreement of both methods was excellent (kappa = 0.84) for assignment of lymph node involvement but only fair (kappa = 0.50) for extranodal disease. A difference with P <.05 (McNemar test) was considered significant in regard to exclusion of disease with PET/CT, compared with contrast-enhanced CT., Conclusion: PET/CT performed with nonenhanced CT is more sensitive and specific than is contrast-enhanced CT for evaluation of lymph node and organ involvement, especially regarding exclusion of disease, in patients with Hodgkin disease and high-grade non-Hodgkin lymphoma., (Copyright RSNA, 2004)

The aim of this study was to assess the frequency and severity of respiration-induced curvilinear respiration artifacts (RICA) on co-registered positron emission tomography/computed tomography (PET/CT) images acquired on a combined PET/CT scanner before and after modifying the respiration protocol for CT scanning, with retrospective analysis of two groups of 100 patients each, before and after implementing a respiration protocol with breath-hold (BH) in the normal expiration position for the acquisition of the CT images. The CT data were used as attenuation map and for image co-registration. A ranking of co-registered PET/CT and PET images (including maximum intensity projection) was done by two observers in consensus using a scale from 0 to 3. Zero indicated that no RICA was visible and 1, 2, and 3 described artifact with increasing severity. A significant difference in RICA occurrence was found between the two groups ( p<0.0001). There was a 45% decrease of artifact frequency when using the normal expiration protocol and a 68% decrease of grade-2 and grade-3 artifacts ( p=0.004). The results of this study suggest that BH during the normal expiration position for CT scanning can be recommended to reduce the occurrence and the severity of RICA on PET/CT.

Experience in our and other institutions with PET/CT imaging of lung and head and neck cancers has shown that this new modality has higher specificity and sensitivity than PET alone and in certain settings even when compared to PET and CT viewed side by side. The largest experience exists with non-small cell lung cancer (NSCLC), in which it has been demonstrated that PET/CT is superior to PET and CT in T and in N staging. Superiority in M staging has yet to be demonstrated. CT contrast media enhancement is probably only necessary when a substantial mediastinal tumor component is present. In such cases, delineation of tumor from vascular structures is relevant. In ENT tumors, PET/CT also appears to be superior to PET, and probably also to PET and CT viewed side by side. Early information suggests that contrast media enhancement for staging may not be required, but the data available is still limited. In both settings, it is interesting to note that in a number of patients, second metachronous tumors are discovered with PET/CT, mainly localized in the GI tract.

Objective: To assess the clinical effect of an early follow-up positron emission tomography (PET) examination at the time of the first routine clinical control in patients with advanced-stage head and neck squamous cell carcinoma (HNSCC)., Design: Prospective, nonrandomized, case-control study., Setting: Single referral center., Patients and Intervention: A total of 26 patients (mean age, 56 years) with histologically confirmed stage III-IV HNSCC underwent PET before and approximately 6 weeks after the end of a combined treatment with radiation and chemotherapy with curative intent. The PET findings were confirmed by histologic analysis and a 6-month clinical follow-up., Main Outcome Measures: The presence of distant metastases, secondary synchronous cancers, and residual locoregional tissue was confirmed, and the effect on further clinical management was assessed., Results: Using PET, we correctly identified residual tumor tissue, distant metastases, or a second primary tumor in 10 patients, 5 of whom had no clinical evidence of such findings. Results were true negative in 14 cases; false positive in 1; and false negative in 1. Sensitivity and specificity for follow-up PET scans were 90.9% and 93.3%, respectively. All patients with positive findings were evaluated for further treatment such as salvage surgery., Conclusions: Whole-body PET scanning approximately 6 weeks after completion of a combined treatment regimen with radiation and chemotherapy can reliably identify locoregional residual cancer and distant metastases or secondary tumors in patients with advanced-stage HNSCC and has a direct influence on management decisions.

Objective: The purpose of this study was to evaluate the influence of (68)Ge-based and CT-based attenuation correction as well as two standard image reconstruction algorithms on the appearance of artefacts due to dental hardware. Additionally, the intensity of such artefacts was compared with (18)F-fluorodeoxyglucose (FDG) uptake in patients with known oral cavity squamous cell cancer., Methods: Thirty-two metallic and non-metallic objects used for dentistry/dental surgery were scanned in a water-bath filled with FDG on a combined PET/CT scanner. Images were reconstructed with either CT-based or (68)Ge-based transmission data and by using iterative reconstruction or filtered backprojection. The intensity of artefacts was assessed visually using a subjective scale from 0 (no artefact visible) to 4 (very strong artefact), and by quantitative measurements. In a second study, images of 30 patients with known squamous cell cancer and dental hardware were retrospectively analysed by two observers, again using a visual assessment grading system. Wilcoxon signed rank test was used for statistical comparisons., Results: Eighteen of 32 objects caused artefacts, which were visible with both attenuation correction methods. CT-based attenuation correction was visually more intense than (68)Ge-based attenuation correction (P<0.0001), and the measured (18)F concentration was also higher (P=0.0002). No difference was found between the reconstruction algorithms. In 28 of 30 patients the primary tumour was visible. FDG uptake in the primary tumour was significantly higher than measured (18)F concentration in artefacts (P<0.0001)., Conclusion: Attenuation correction of PET images generates artefacts adjacent to dental hardware that mimic FDG uptake. In this series, the primary lesion was discriminated from artefacts.

The aim of this study is to evaluate the additional clinical information provided by whole body positron emission tomography (PET) with fluorodeoxyglucose (FDG) for initial staging of patients with squamous cell carcinoma (SCC) of the oral cavity. PET scans from the head to the pelvic floor of 34 consecutive patients (22 male, 12 female; mean age 71 years) with histologically confirmed SCC of the oral cavity were retrospectively evaluated. Clinical information including CT of the head and neck and chest X-Ray or chest CT was compared with information on nodal involvement and distant metastases or secondary tumours obtained with PET. The primary tumour was identified with PET in 33 of 34 patients (97%). In 27 Patients (81%) the clinical N-stage was confirmed with PET. In two Patients (6%) additional pathologic loco-regional lymph nodes were found. In five patients more lymph nodes were identified with CT. Distant lesions were seen with PET imaging in bone, lung, mediastinum, liver and colon. In three patients (6%) distant metastases were correctly identified. In another four patients (12%) a secondary cancer was detected. One false positive finding was described with PET. In five of 34 patients (15%) the additional findings as revealed with PET lead to a change of treatment. Whole body PET provides relevant additional information to a standard clinical staging procedure in patients with oral cavity SCC. The detection of distant metastases and secondary primary tumours can have a great impact on patient management.

We report the case of a 68-year-old patient with a known paravertebral malignant schwannoma, sent to us for postoperative staging. A combined whole-body PET/CT scan showed only poor (18)F-fluorodeoxyglucose uptake in the region of the primary tumor but distinct increased fluorodeoxyglucose uptake in the left and right thyroid gland. Thyroid sonography showed two hypoechogenic nodules. Ultrasound-guided fine-needle aspiration biopsy of one nodule showed oxyphil transformed cells, compatible with malignancy. Based on these findings, the patient underwent a subtotal thyroidectomy. Histopathology of the specimen revealed a chronic follicular Hashimoto's thyroiditis. This case demonstrates that Hashimoto's thyroiditis can mimic thyroid cancer in PET but also in sonography and fine-needle aspiration biopsy.

The aim of this study was to compare MRI of the breast with (18)F-fluoro-deoxy-glucose (FDG) positron emission tomography (PET) in patients with suspected local or regional breast cancer recurrence or suspected contralateral breast cancer. Thirty-two patients (mean age 57.2 years, age range 32-76 years) with suspected loco-regional recurrence ( n=19), chest wall recurrence ( n=5), and suspected secondary tumor of the contralateral breast ( n=8) underwent MRI of the breast and FDG PET of the whole body and breast region. Cytology/histology ( n=17) or a clinical follow-up examination ( n=15) with additional imaging served as the standard of reference. A McNemar test was performed to compare PET and MRI, and kappa was determined to quantify agreement of both methods. Sensitivity was 79 and 100%, specificity was 94 and 72%, and accuracy was 88 and 84% for MRI and PET, respectively. Additional metastases outside the field of view of MRI were found in PET in 5 patients. In this study both imaging methods had comparable accuracy. The detection of distant metastases with whole-body PET imaging can influence patient management.

Our objective was to study the effect of metal-induced artifacts on the accuracy of the CT-based anatomic map as a prerequisite for attenuation correction of the positron emission tomography (PET) emission data. Twenty-seven oncology patients with dental metalwork were enrolled in the present study. Data acquisition was performed on a PET/CT in-line system (Discovery LS, GE Medical Systems, Milwaukee, Wis.). Attenuation correction of emission data was done twice, using an 80-mA CT scan (PET(CT80)) and a (68)Ge transmission scan (PET(68Ge)). Average count in kBq/cc was measured in regions with and without artifacts and compared for PET(CT80) and PET(68Ge). Data analysis of region of interests (ROIs) revealed that the ratio (ROIs PET(CT80)/ROIs PET(68Ge)) and the difference (ROIs PET(CT80) minus ROIs PET(68Ge)) had a higher mean of values in regions with artifacts than in regions without artifacts (1.2+/-0.17 vs 1.06+/-0.06 and 0.68+/-0.67 vs 0.15+/-0.17 kBq/cc, respectively). For most of the studied artifactual ROIs, the PET(CT80) values were higher than those of the PET(68Ge). Attenuation correction of PET emission data using an artifactual CT map yields false values in regions nearby artifacts caused by dental metalwork. This may falsely estimate PET quantitative studies and may disturb the visual interpretation of PET scan.

The purpose of this study was to calculate disease probabilities based on data of patients with head and neck cancer in the register of our institution and to perform a systematic review of the available data on the accuracy of PET in the primary assessment and follow-up of patients with head and neck cancer. The pre-test probability of head and neck cancer among patients in our institutional data registry was assessed. Then the published literature was selected and appraised according to a standard protocol of systematic reviews. Two reviewers independently selected and extracted data on study characteristics, quality and accuracy. Accuracy data were used to form 2 x 2 contingency tables and were pooled to produce summary receiver operating characteristic (ROC) curves and summary likelihood ratios for positive and negative testing. Finally post-test probabilities were calculated on the basis of the pre-test probabilities of this patient group. All patients had cytologically or histologically proven cancer. The prevalence of additional lymph node metastases on PET in staging examinations was 19.6% (11/56), and that of locoregional recurrence on restaging PET was 28.6% (12/42). In the primary assessment of patients, PET had positive and negative likelihood ratios of 3.9 (2.56-5.93) and 0.24 (0.14-0.41), respectively. Disease probabilities were therefore 49.4% for a positive test result and 5.7% for a negative test result. In the assessment of recurrence these values were 3.96 (2.8-5.6) and 0.16 (0.1-0.25), resulting in probabilities of 49.7% and 3.8%. PET evaluation for involvement of lymph nodes had positive and negative likelihood ratios of 17.26 (10.9-27.3) and 0.19 (0.13-0.27) for primary assessment and 11.0 (2.93-41.24) and 0.14 (0.01-1.88) for detection of recurrence. The probabilities were 81.2% and 4.5% for primary assessment and 73.3% and 3.4% for assessment of recurrence. It is concluded that in this clinical setting the main advantage of PET is the ability to reliably rule out the presence of disease in both staging and restaging. Further research is required to derive probabilities for individual patients from sequential testing as applied in the diagnostic work-up of patients with head and neck cancer.

The aim of this study was to evaluate the respiration position, which is optimal for co-registration of abdominal CT images, and the corresponding positron emission tomography (PET) scan in a new combined PET/CT system. Ten patients (5 men, 5 women; age 57.7+/-15.3 years, age range 34-80 years) underwent imaging for tumor staging on a combined PET/CT scanner (Discovery LS, GE Medical Systems, Milwaukee, Wis.). The PET emission images were acquired during normal shallow breathing and during CT scanning the patients performed four different breathing tasks: free breathing (FB); maximum inspiration (MaxInsp); maximum expiration (MaxExp); and normal expiration (NormExp). NormExp was defined as the respiratory level that was reached when the patient first inhaled and then exhaled without forcing expiration, and then held the breath in this position. Movements of the spleen, liver, left and right kidney, and the bladder were measured by using the promontory of the sacrum as a reference point and measuring the distance from this point to the abdominal organs in the PET and CT images by two independent observers. Statistical comparison of the measured distances between the CT scans and the PET scan were made using a Wilcoxon signed-rank test with Bonferroni correction. Repeated-measures analysis of variance served for the assessment of intraobserver and interobserver agreement. There was no significant difference between NormExp and FB indicating that both respiration protocols are suitable for PET/CT image co-registration of abdominal studies. In contrast, the MaxExp and MaxInsp protocol are not suitable. The NormExp and FB respiration protocol are both suitable for the co-registration of abdominal PET/CT studies. In most patients the mismatch of abdominal organs will be lower than the resolution of the final co-registered PET/CT image.

This study was performed to assess the potential benefit of positron emission tomography (PET) using fluorine-18 fluorodeoxyglucose (FDG) in patients with cervical metastasis of squamous cell carcinoma from an unknown primary tumour. Eighteen patients with cervical metastasis of squamous cell carcinoma from an unknown primary who were assessed by physical examination including transnasal fibre-endoscopy and radiological work-up with computed tomography were included in this prospective tertiary referral centre cohort study. The results of the search for the primary with rigid panendoscopy of the upper aerodigestive tract were compared to the evaluation with FDG PET. Panendoscopy revealed a primary tumour in 8/18 (44%) patients. PET accurately diagnosed five of these eight primary tumours, and gave one false positive and three false negative scans, resulting in a sensitivity of 63%, a specificity of 90%, an accuracy of 78%, a positive predictive value of 83% and a negative predictive value of 75%. Small primaries or primaries in areas with physiologically increased FDG uptake can be missed with PET owing to the limited resolution of the camera (approximately 5 mm). Our study in a small number of patients suggests that PET does not provide benefit in terms of detecting additional primary tumours if applied in addition to extensive clinical work-up. Considering its high specificity, PET could be of value as an initial evaluation instrument, reserving the need for extensive work-up to patients with negative scans.

Combined positron emission tomographic (PET)/computed tomographic (CT) scanners allow the use of CT data for attenuation correction of PET images. Eight patients with cancer underwent PET/CT scanning. Transmission scanning was performed with conventional attenuation correction and with CT scanning during maximum inspiration and normal expiration. Image quality was visually compared and fluorine 18 activities were measured in volumes of interest in the lung and myocardium. Analysis of variance for repeated measures revealed a significant decrease (P =.0001) in measured activities between PET images corrected with CT data acquired during maximum inspiration and those corrected with the conventional attenuation correction method or with CT data acquired during normal expiration. Deep inspiration during CT can result in severe deterioration in the final PET image.

Aim: To evaluate the role of [18F]-fluorodeoxyglucose positron emission tomography (FDG-PET) in patients presenting with a suspicion of breast cancer relapse after primary treatment., Materials and Methods: Sixty consecutive female patients with clinical (n=35) or radiological (n=25) suspicion of breast cancer recurrence were evaluated by FDG-PET. Positive PET findings were further evaluated by histological examination or clinical and radiological follow-up. In 25 patients, the serum tumor marker (CA 15-3) status was compared to the PET results., Results: Disease relapse was proven in 40 patients. Additionally, in three patients a second cancer was diagnosed with (n=1), and without (n=2) concomitant disease relapse. PET missed local recurrence in three patients, and was false positive in another four. In patient-based analysis, the overall sensitivity, specificity, and accuracy were 89%, 84%, and 87%, and 100%, 97%, and 98% for locoregional recurrence and distant metastases, respectively. FDG-PET was more sensitive than the serum tumor marker CA 15-3 in detecting relapsed breast cancer., Conclusion: FDG-PET is a valuable tool in the follow-up of patients with breast cancer.

Hip prosthetic material and a steel rod were scanned in a water bath of fluorine 18 fluorodeoxyglucose (FDG) with positron emission tomographic (PET) and PET/computed tomographic (CT) scanners to evaluate the generation of artifacts adjacent to the metal. The influences of attenuation correction (AC), positioning of the object, and image reconstruction were examined. Use of CT- and germanium 68-based AC resulted in generation of artifacts that mimicked increased FDG uptake. These artifacts were more evident when the object was moved between the emission and transmission scans. When attenuation-weighted iterative reconstruction was used, these artifacts were less evident.

Unlabelled: The purpose of this study was to evaluate the accuracy of image coregistration of PET and CT (PET/CT) images in patients with lung lesions and the influence of the breathing protocol during CT., Methods: Seventy-five patients with a solitary and well-circumscribed pulmonary lesion (non-small cell lung cancer; size, 10-30 mm) underwent PET/CT on a combined scanner. CT was acquired during shallow breathing in 37 patients and during normal expiration (i.e., the level reached when the patient exhaled without forcing expiration and then held the breath) in 38 patients. The volume of interest of each lesion was defined separately on PET and CT images, and the geometric center of gravity (COG) was assessed. The distance of COGs between the PET image and the CT image was measured. All lesions were classified according to 4 lung regions: apical, peripheral, central, and lung base. The mismatch between COG(PET) and COG(CT) was compared between regions and patient groups using a 2-way ANOVA with the Bonferroni-Dunn test for post hoc comparisons., Results: The range of COG distance between PET and CT was 1.7-5.4 mm in the apex, 0.5-14.7 mm in the periphery, 0.7-5.9 mm centrally, and 2.9-11.3 mm in the lung base. The match between PET and CT was significantly better in patients who had the CT scan obtained during normal expiration than in patients who performed shallow breathing during CT scanning (P = 0.024). No reciprocal effects were found (interaction P = 0.76). The mismatch of lesions depends significantly on lung region (P < 0.0001). Post hoc analysis showed a significant difference between the upper 2 regions and the lower 2 regions (all P < or = 0.002) but not between the apex and the central region (P = 0.95) and between the peripheral region and the lung base (P = 0.15). The lesion size had no influence on the COG mismatch., Conclusion: The match of lung lesions in coregistered PET/CT images is better when acquiring the CT scan during normal expiration. The coregistration accuracy is better in the upper and central parts of the lung. The normal expiration protocol is suggested to be superior to shallow breathing during CT scanning.

The authors describe the initial application for tumor staging with an in-line system with a positron emission tomographic (PET) scanner and a multi-detector row helical computed tomographic (CT) scanner combined in one machine. Fifty-three patients underwent imaging with four CT tube currents and PET emission and transmission data acquisition. Stepwise analysis of coregistered images revealed a significant (P <.05, McNemar test) improvement in lesion classification between PET images alone and coregistered images from the PET-CT examination., (Copyright RSNA, 2002)

Positron emission tomography (PET) with fluorodeoxyglucose (FDG) was performed for preoperative staging of lung cancer. In six of 184 patients, there was an intense FDG accumulation in the lower anterior neck. Fusion of PET and computed tomographic images revealed that the focal FDG uptake was localized in the internal laryngeal muscles. This finding was a result of compensatory laryngeal muscle activation caused by contralateral recurrent laryngeal nerve palsy due to direct nerve invasion by lung cancer of the left mediastinum or lung apices. The knowledge of this pitfall is important to avoid false-positive PET results.

Because anatomical information on fluorine-18 fluorodeoxyglucose (FDG) whole-body positron emission tomography (PET) images is limited, combination with structural imaging is often important. In principle, software co-registration of PET and computed tomography (CT) data or dual-modality imaging using a combined PET-CT camera has an important role to play, since "hardware-co-registered" images are thereby made available. A major unanswered question is under which breathing protocol the respiration level in the CT images of a patient will best match the PET images, which represent summed images over many breathing cycles. To address this issue, 28 tumour patients undergoing routine FDG PET examinations were included in this study. In ten patients, PET and CT were performed using a new combined high-performance in-line PET-CT camera without the need for repositioning of the patient, while in 18 patients imaging was performed on separate scanners located close to each other. CT was performed at four respiration levels: free breathing (FB), maximal inspiration (MaxInsp), maximal expiration (MaxExp) and normal expiration (NormExp). The following distances were measured: (a) between a reference point taken to be the anterior superior edge of intervertebral disc space T10-11 and the apex of the lung, (b) from the apex of the lung to the top of the diaphragm, (c) from the apex of the lung to the costo-diaphragmatic recess and (d) from the reference point to the lateral thoracic wall. Differences between CT and corresponding PET images in respect of these distances were compared. In addition, for each of 15 lung tumours in 12 patients, changes in tumour position between PET and CT using the same protocol were measured. CT during NormExp showed the best fit with PET, followed by CT during FB. The mean differences in movement of the diaphragmatic dome on CT during NormExp, FB, MaxInsp and MaxExp, as compared with its level on PET scan, were, respectively, 0.4 mm (SD 11.7), -11.6 mm (13.3), -44.4 mm (25.5) and -9.5 mm (25.6). CT acquired in MaxExp and MaxInsp is not suitable for image co-registration owing to the poor match of images in MaxInsp and because of difficulties with patient performance in MaxExp. With reference to lung lesions, NormExp showed the best results, with a higher probability of a good match and a smaller range of measured values in comparison with FB. Image misregistration in combined PET-CT imaging can be minimized to dimensions comparable to the spatial resolution of modern PET scanners. For PET-CT image co-registration, the use of a normal expiration breath-hold protocol for CT acquisition is recommended, independent of whether combined PET-CT systems or stand-alone systems are used.

Germanium-68 based attenuation correction (PET(Ge68)) is performed in positron emission tomography (PET) imaging for quantitative measurements. With the recent introduction of combined in-line PET/CT scanners, CT data can be used for attenuation correction. Since dental implants can cause artefacts in CT images, CT-based attenuation correction (PET(CT)) may induce artefacts in PET images. The purpose of this study was to evaluate the influence of dental metallic artwork on the quality of PET images by comparing non-corrected images and images attenuation corrected by PET(Ge68) and PET(CT). Imaging was performed on a novel in-line PET/CT system using a 40-mAs scan for PET(CT) in 41 consecutive patients with high suspicion of malignant or inflammatory disease. In 17 patients, additional PET(Ge68) images were acquired in the same imaging session. Visual analysis of fluorine-18 fluorodeoxyglucose (FDG) distribution in several regions of the head and neck was scored on a 4-point scale in comparison with normal grey matter of the brain in the corresponding PET images. In addition, artefacts adjacent to dental metallic artwork were evaluated. A significant difference in image quality scoring was found only for the lips and the tip of the nose, which appeared darker on non-corrected than on corrected PET images. In 33 patients, artefacts were seen on CT, and in 28 of these patients, artefacts were also seen on PET imaging. In eight patients without implants, artefacts were seen neither on CT nor on PET images. Direct comparison of PET(Ge68) and PET(CT) images showed a different appearance of artefacts in 3 of 17 patients. Malignant lesions were equally well visible using both transmission correction methods. Dental implants, non-removable bridgework etc. can cause artefacts in attenuation-corrected images using either a conventional 68Ge transmission source or the CT scan obtained with a combined PET/CT camera. We recommend that the non-attenuation-corrected PET images also be evaluated in patients undergoing PET of the head and neck.

An infected cyst in autosomal dominant polycystic kidney disease was identified with a combined positron emission tomographic (PET) and computed tomographic (CT) system, an experimental setup mimicking an integrated CT-PET scanner. Image fusion of fluorine 18 fluorodeoxyglucose PET and CT images allowed exact localization of the infected cyst among many cysts identified on previous CT and magnetic resonance images. Confirmation was obtained instantly, followed by CT-guided percutaneous puncture. Integrated imaging systems hold promise for direct PET-guided puncture of areas of increased fluorodeoxyglucose uptake by using the anatomic accuracy of CT.

Periodic lateralized epileptiform discharges (PLEDs) are a well defined electroencephalographic entity but whether PLEDs represent an ictal condition or not remains debated. Much work has been done using electroencephalography (EEG) but new approaches using cerebral perfusion imaging may give more information about this question. We aimed to evaluate if PLEDs were associated with high regional cerebral blood flow (rCBF). We studied 18 patients with PLEDs and different pathologies, and performed brain single-photon-emission computed tomography (SPECT) during and, for three cases, after the disappearance of PLEDs. Qualitative variations and locations of rCBF were compared with PLEDs. Association with seizures and type of seizures were also assessed. SPECT showed high rCBF in 18/18 patients (100%). The location of PLEDs and high rCBF matched in 17/18 cases (94%). In the three cases where SPECT was performed after PLEDs disappeared, the high rCBF had cleared (100%). Eighteen cases (100%) presented seizures before recording of PLEDs, mainly motor (partial motor or generalized tonic-clonic). Where there was a decreased rCBF (related to a lesion) there was little relationship to PLEDs and all patients with decreased rCBF had an adjacent increased rCBF. These results confirm preliminary case reports. Hyperperfusion adds further to the argument that PLEDs may be related to a form of partial status epilepticus., (Copyright 2001 BEA Trading Ltd.)