Positron Emission Tomography Scan Findings Research Articles

`DIAGNOSTIC PITFALLS IN THE INTERPRETATION OF EXTRANODAL LYMPHOMAS – A CASE SERIES

Extranodal non-Hodgkin’s lymphoma (ENNHL) by definition affects any organ or tissue excluding lymph node and spleen. Histopathological examination is the investigation of choice that further helps in deciding the advanced diagnostic panel of the immunohistochemistry (IHC) and molecular studies. Histopathological evaluation as such is not straight forward, since there is high probabilty of misdiagnosis and diagnostic pitfalls due to inadequate material, sampling and processing errors, inadequate clinical information, personal subjectivity of clinicians and pathologists, and IHC-related errors. This case series is reported at a tertiary care hospital. Total three cases of ENNHL are reported, where the process of diagnosis went through few pitfalls before the ultimate diagnosis was made. The first case was a jejunal mass clinically diagnosed as carcinoma, histopathologically found to be extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue transforming to diffuse large B-cell lymphoma in the mesenteric lymph node. Second case describes misinterpretation of small lymphocytic lymphoma as adenocarcinoma deposit in liver by clinical and radiological evaluation. Third case describes follicular dendritic cells of spleen where the first two biopsies showed chronic lymphocytic gastritis and reactive lymphadenitis and finally the third from spleen confirmed the diagnosis. The diagnosis of ENNHL in biopsies requires clinicopathological suspicion with discussion and repeat biopsies if inconclusive. Pathologist should be aware of the gross and microscopic features indicating high-grade NHL transformation in surgical specimens. During the initial clinical evaluation and follow-up of low-grade ENNHL, positron emission tomography scan findings can be used, to effectively target biopsy from areas or regional lymph nodes suspicious of high-grade transformation.

CARDIAC SARCOIDOSIS: WHEN THE RIGHT VENTRICLE ISN’T RIGHT

CARDIAC SARCOIDOSIS: WHEN THE RIGHT VENTRICLE ISN’T RIGHT

Clinical Predictors of Locally Advanced Pathology in Esophageal Adenocarcinoma.

BackgroundIn patients with resectable esophageal adenocarcinoma (EAC), the decision for neoadjuvant treatment depends on clinical staging with endoscopic ultrasound (EUS) and positron-emission tomography (PET) scan. Patients with locally advanced EAC pathology misclassified as early EAC by clinical staging are missing the opportunity to receive neoadjuvant therapy. We aim to identify predictors of locally advanced pathology in EAC to determine more accurately those who benefit from neoadjuvant therapy. MethodsRetrospective study of patients who underwent upfront endoscopic or surgical resection for EAC without neoadjuvant therapy from January 2011 to December 2017 was performed. Clinical characteristics, EUS, PET scan and histologic findings were analyzed. Multivariable analysis of predictors of locally advanced stage was performed and a risk prediction score was developed.ResultsA total of 97 patients were included; 68 patients were staged as early EAC (pT1 or pT2 and pN0) and 29 patients were staged as locally advanced EAC (pT1 or pT2 with pN1 and pT3 or pT4 irrespective of N status). In a predictive model of EAC, patients presenting with dysphagia, tumor size >2 cm, exophytic mass appearance on endoscopy and absence of hiatal hernia were more likely to be have locally advanced pathology with a probability of 70% (C-statistic 0.766).ConclusionsA risk prediction model based on the presence of dysphagia, tumor size >2 cm, exophytic mass appearance and absence of hiatal hernia can be used to identify locally advanced pathology in EAC patients.

Clinical Risk Prediction Model for Neoadjuvant Therapy in Resectable Esophageal Adenocarcinoma.

Clinical staging with endoscopic ultrasound (EUS) and positron emission tomography (PET) is used to identify esophageal adenocarcinoma (EAC) patients with locally advanced disease and therefore, benefit from neoadjuvant therapy. However, EUS is operator dependent and subject to interobserver variability. Therefore, we aimed to identify clinical predictors of locally advanced EAC and build a predictive model that can be used as an adjunct to current staging methods. This was a cross-sectional study of patients with EAC who underwent preoperative staging with EUS and PET scan followed by definitive therapy at our institution from January 2011 to December 2017. Demographic data, symptoms, endoscopic findings, EUS, and PET scan findings were obtained. Four hundred and twenty-six patients met the study criteria, of which 86 (20.2%) patients had limited stage EAC and 340 (79.8%) had locally advanced disease. The mean age was 65.4±10.3 years of which 356 (83.6%) were men and 393 (92.3%) were White. On multivariable analysis, age (above 75 or below 65 y), dysphagia [odds ratio (OR): 2.84], weight loss (OR: 2.06), protruding tumor (OR: 2.99), and tumor size >2 cm (OR: 3.3) were predictive of locally advanced disease, while gastrointestinal bleeding (OR: 0.36) and presence of visible Barrett's esophagus (OR: 0.4) were more likely to be associated with limited stage. A nomogram for predicting the risk of locally advanced EAC was constructed and internally validated. We constructed a nomogram to facilitate an individualized prediction of the risk of locally advanced EAC. This model can aid in decision making for neoadjuvant therapy in EAC.

FDG PET Positive Cardiac Amyloidosis

Background Cardiac positron emission tomography (PET) is routinely utilized to diagnose cardiac sarcoidosis, but may be positive in other cardiac conditions that result in myocardial inflammation. ATTR cardiac amyloidosis, an infiltrative disease that causes atrial arrhythmias and heart failure, is not typically thought to present with an inflammatory process. However, we observed four cases in which 18F-flurodeoxyglycose (FDG) PET scan findings were suspicious for cardiac sarcoidosis, but right ventricular endomyocardial biopsy (RV EMB) pathology specimens revealed ATTR wild-type (ATTRwt) cardiac amyloidosis. Methods Retrospective chart review was performed on patients with a positive cardiac FDG PET scan who also had a concomitant diagnosis of ATTR cardiac amyloidosis at Mayo Clinic Rochester between January 1, 2000 and March 24, 2019. Results Four patients with clinical presentation suggestive of cardiac sarcoidosis had positive FDG PET scans but were found to have biopsy-proven ATTRwt cardiac amyloidosis. All four patients were male with an average age of 71 years (62, 75). Two patients presented with ventricular arrhythmias and had transthoracic echocardiograms that were not suggestive of cardiac amyloidosis. FDG PET scans of these two patients revealed myocardial FDG uptake, similar to what can be seen in cardiac sarcoidosis. Both patients underwent RV EMB, with pathology specimens and mass spectrometry revealing ATTRwt cardiac amyloidosis. One of these two patients had a positive nuclear 99mTechnetium-pyrophosphate (PYP) scan (H/Cl ratio 1.9) and the other had a negative PYP scan (H/CL 1.2). The third patient, with a history of biopsy proven pulmonary sarcoidosis, presented with atrial fibrillation and conduction abnormalities. FDG PET scan revealed myocardial perfusion defects and patchy FDG uptake, but RV EMB revealed ATTRwt cardiac amyloidosis. Nuclear PYP was positive (H/Cl ratio of 1.8). The fourth patient presented with intermittent high grade AV block and underwent pacemaker implantation. He later developed frequent monomorphic premature ventricular contractions. Cardiac FDG PET scan illustrated FDG uptake, but the concurrent CT trunk did not illustrate any FDG uptake suspicious for extra-cardiac sarcoidosis. RV EMB was consistent with ATTRwt cardiac amyloidosis, but PYP was negative. Discussion These findings suggest that inflammation could play a role in ATTR cardiac amyloidosis. We have previously seen inflammatory changes of lymphohistiocytic infiltration around areas of amyloid protein deposition on biopsy specimens in ATTR cardiac amyloidosis. The role of therapy targeted at stabilizing transthyretin versus immunosuppressive agents in this subgroup remains unclear.

A Unique Case of Rituximab-Induced Crohnʼs Disease: A Case Report and Review of Literature

Rituximab is a humanized monoclonal antibody against CD20 which is a mainstay of therapy for a wide variety of B cell malignancies. There are only two reported cases of Crohn's disease following treatment with Rituximab in the literature. We present a very unique case of a 58 year old female who was treated with Rituximab, Cyclophosphamide, Doxorubicin, Vincristine and Prednisolone (R-CHOP) regimen for initial diagnosis of follicular cell lymphoma of the tonsils. She was treated with prolonged maintenance Rituximab treatment for a recurrence of the lymphoma two years later and the treatment was continued for two and a half years. Three years later she was noted to have increased activity in the terminal ilium and mesenteric lymph nodes on a routine positron emission tomography (PET) scan. At that time, she was asymptomatic and refused any further workup or treatment. Another PET scan done two years later showed enlarged mesenteric lymph nodes with increased activity in the terminal ileum and the spleen. A colonoscopy performed at that time revealed inflammation with extensive ulceration in the terminal ileum. Biopsy demonstrated severely active chronic nonspecific ileitis with ulceration and a small granulomatous lesion. She was then re-treated again with 4 cycles of rituximab for a presumed recurrence. Two months after the treatment, she developed severe abdominal pain leading to an emergency room visit. A computerized tomography (CT) scan showed thickening in the distal descending colon as well as the entire sigmoid colon with surrounding fat stranding. She was treated with oral ciprofloxacin and metronidazole for 10 days with improvement in the symptoms. In a follow-up PET scan done a month later, the mesenteric adenopathy resolved but the activity in the terminal ileum was unchanged and there was new activity in the sigmoid colon. The patient refused further endoscopic examination, however the PET scan findings of worsening of the bowel inflammation and resolution of the adenopathy strongly suggests Rituximab induced Crohn's disease. This case portrays the importance of being alert to the possibility of Crohn's disease occurring as complication of Rituximab treatment. This case is unique as the Crohn's disease occurred almost three years after the initial Rituximab treatment. Management of Crohn's disease in patients with a history of lymphoma can be challenging due to the risk of lymphoma from Anti-TNF and immunomodulatory treatments.Figure: PET Scan showing increased uptake in the mesenteric lymph nodes and terminal ileum.Figure: Colonoscopy image of the terminal ileum.

Regional Cerebral Glucose Metabolism and its Association with Phenotype and Cognitive Functioning in Patients with Autism.

Introduction:In spite of three decades of neuroimaging, we are unable to find consistent and coherent anatomical or pathophysiological basis for autism as changes are subtle and there are no studies from India.Aim:To study the regional cerebral glucose metabolism in children with autism using positron emission tomography (PET) scan and to study the behavior and cognitive functioning among them.Materials and Methods:Ten subjects (8–19 years) meeting Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria for autism were evaluated on Childhood Autism Rating Scale (CARS), trail making test (TMT) A and B, Wisconsin card sorting test, Raven's progressive matrices, and PET scan. A control group of 15 matched subjects without any brain pathology or neurological disorder was similarly studied.Results:Four out of the ten patients with autism had abnormal PET scan findings, and in contrast, none of the patients in the control group had abnormal PET scan. Of the four patients with abnormality in the PET scan, two patients had findings suggestive of hypometabolism in cerebellum bilaterally; one patient showed bilateral hypometabolism in anterior temporal cortices and cerebellum, and the fourth patient had hypermetabolism in the bilateral frontal cortices and medial occipital cortices. Subjects with autism performed poorly on neuropsychological testing. Patients with abnormal PET scan findings had significantly higher scores on the “body use” domain of CARS indicating more stereotypy.Conclusion:Findings of this study support the view of altered brain functioning in subjects with autism.

Chapter 11 - Positron Emission Tomography

Positron emission tomography (PET) is a minimally invasive imaging procedure with a wide range of clinical and research applications. PET allows for the three-dimensional mapping of administered positron-emitting radiopharmaceuticals such as (18)F-fluorodeoxyglucose (for imaging glucose metabolism). PET enables the study of biologic function in both health and disease, in contrast to magnetic resonance imaging (MRI) and computed tomography (CT), that are more suited to study a body's morphologic changes, although functional MRI can also be used to study certain brain functions by measuring blood flow changes during task performance. This chapter first provides an overview of the basic physics principles and instrumentation behind PET methodology, with an introduction to the merits of merging functional PET imaging with anatomic CT or MRI imaging. We then focus on clinical neurologic disorders, and reference research on relevant PET radiopharmaceuticals when applicable. We then provide an overview of PET scan interpretation and findings in several specific neurologic disorders such as dementias, epilepsy, movement disorders, infection, cerebrovascular disorders, and brain tumors.

Accelerated hemithoracic radiation followed by extrapleural pneumonectomy for malignant pleural mesothelioma

ObjectiveTo evaluate a new protocol of accelerated hemithoracic intensity-modulated radiation therapy (IMRT) followed by extrapleural pneumonectomy (EPP) for patients with resectable malignant pleural mesothelioma (MPM). MethodsA total of 25 Gy of radiation was delivered in 5 daily fractions over 1 week to the entire ipsilateral hemithorax with concomitant boost of 5 Gy to volumes at high risk based on computed tomography and positron emission tomography scan findings. EPP was performed at 6 ± 2 days after the end of radiation therapy. Adjuvant chemotherapy was offered to patients with ypN2 disease. ResultsA total of 62 patients were included between November 2008 and October 2014. One patient died in the hospital 2 months after EPP, for an operative mortality of 1.6%, and 2 died after discharged from the hospital for an overall treatment-related mortality (grade 5 toxicity) of 4.8%. Twenty-four patients (39%) developed grade 3 to 5 (grade 3+) complications. On final pathology, 94% of the patients were stage III or IV, and 52% had ypN2 disease. The median survival for all patients as an intention-to-treat analysis was 36 months. The median overall survival and disease-free survival was 51 and 47 months, respectively, in epithelial subtypes, compared with 10 and 8 months in biphasic subtypes (P = .001). Ipsilateral chest recurrence occurred in 8 patients. ConclusionsAccelerated hemithoracic IMRT followed by EPP has become our preferred approach for resectable MPM. The results have been encouraging in patients with epithelial subtype.

Evaluation of PET imaging in treatment decision making for early stage head and neck squamous cell cancer

e17017 Background: Positron emission tomography (PET) scanning is widely used in staging of patients (pts.) with head and neck squamous cell cancers (HNSCC). However, the role of PET scan in pts. with early stage disease and clinically negative nodes remains controversial. The purpose of our study was to correlate preoperative PET scan findings in early stage disease with operative pathological findings of neck dissection. Methods: A retrospective review of medical records of all pts. treated at Long Island Jewish Medical Center with T1N0 HNSCC from 2002 to 2008 was undertaken. Institutional Review Board approval was obtained for this study. Eligibility criteria included: clinically staged T1N0, documented pre-operative PET scans and primary surgical management including a neck lymph node dissection as part of initial treatment. Data collected included age, gender, physical examination findings, PET scan results, operative pathology and modalities of treatment. Results: Sixty six pts with early stage T1N0 HNSCC were identified. Twelve of sixty six pts met eligibility criteria for this study. Median age was 61 years (range: 27 to 84 yrs), M:F ratio was 1:1. Primary sites of tumor were: tongue (n = 8) 67%; oral cavity (n = 3) 25%; larynx (n = 1) 8%. Preoperative PET scan was positive at primary sites in all pts (n = 12). Additionally, PET positivity was noted in regional lymph node sites in six of twelve pts. Operative pathology confirmed tumor presence in all primary sites. However, nodal involvement was not found in any pt. Median numbers of lymph nodes dissected were 25 (range:13–34). Based on these clinical data, the calculated statistical parameters for preoperative PET scan in detecting occult neck lymph node metastases were: negative predictive value: 100%; positive predictive value: 50%: specificity: 50%; sensitivity: 0%. Conclusions: The clinical application of PET scans in early stage (T1N0) HNSCC may be limited by its high false positive rate. A high negative predictive value suggests that a negative result can exclude metastatic lymph nodes involvement in this group of pts. with early stage disease. Correlation with SUV values of the PET scans and comparisons between the relative PET avidity of the primary tumors and the nodal uptake are ongoing. No significant financial relationships to disclose.

A Unique Case of Pulmonary Hyalinizing Granuloma Associated With FDG-avid PET Scan and Deep Venous Thrombosis

An 83-year-old obese woman with a 60-pack-year smoking history was referred for evaluation of an abnormal chest radiograph [chest x-ray (CXR)]. Her past medical history was significant for recurrent deep venous thrombosis without any predisposing factors. CXR showed a large mass in the right mid lung and another nodule at the right apex, highly suspicious for a neoplastic process. These were not present on a CXR from 2 years earlier. An fluorodeoxyglucose (FDG)-positron emission tomography (PET)/computed tomography (CT) scan revealed that all lesions were strongly FDG-avid. Six CT-guided core-needle lung biopsy specimens were obtained from the lung mass and all contained dense, lamellar, or "ropy" keloid-like collagen bundles arranged in a haphazard pattern. The biopsy specimens lacked significant necrosis and granulomas. Congo red stain with polarization was also negative for amyloid. The diagnosis of pulmonary hyalinizing granuloma (PHG) was made. A complete hypercoagulable workup was performed but no underlying abnormalities were found, including a negative lupus anticoagulant and malignancy workup. The patient was maintained on warfarin and followed with serial CT scans for 1 year, with spontaneous regression in the lung mass. The case is unique as it is the first case that reports an association of PHG with recurrent deep venous thrombosis in the absence of autoimmune or procoagulant factors and emphasizes the need for life-long anticoagulation in such scenarios. Also, we report the FDG-avid PET scan findings here that are novel for this disease in adults and add PHG to the list of diseases causing false-positive PET scans when malignancy is suspected.

EUS with or without FNA is a highly effective modality in the evaluation of positive PET scan findings

Background: Positron emission tomography (PET) is commonly employed to detect distant metastatic disease in patients with known or suspected cancer. When the PET demonstrates uptake near the esophagus, stomach, duodenum, or rectum, EUS can be used to evaluate these areas to confirm or exclude malignant disease. The effectiveness of EUS for this indication is not known. The aim of this study was to evaluate the impact of EUS with or without FNA on the clinical management of patients with positive PET scans.

Marchiafava-Bignami disease: Two cases with magnetic resonance imaging and positron emission tomography scan findings

We report two patients with Marchiafava-Bignami disease (MBD). A 38-year-old male with chronic alcohol abuse developed acute onset cerebellar ataxia and altered sensorium. He was diagnosed to have acute form (Type II) of MBD. Magnetic resonance imaging (MRI) showed extensive lesions involving the corpus callosum in its entire extent and also bilateral corona radiata and centrum semiovale. Corpus callosum had heterogeneous signal changes with ring enhancement. Positron emission tomography scan demonstrated reduced cerebral glucose metabolism diffusely over both the cerebral hemispheres. The second patient was 55-year-old male with chronic alcohol intake developed acute onset vomiting followed by behavioral abnormalities and altered sensorium. MRI showed diffuse lesion involving entire corpus callosum with suggestion of necrosis. Both the patients subsequently recovered, the first patient is back to his previous occupation and the second patient could be rehabilitated with some lighter work in his previous work place. Functional brain imaging may help to understand the pathogenesis of acute MBD and possibly the behavioral manifestations.

Absence of microfollicular basement membrane: A new indicator in the diagnosis of follicular carcinoma thyroid

The thyroid follicles represent a biological continuum. Each follicle is closely related to the follicle that is next to it. The important feature of a follicular carcinoma is a microfollicular pattern. We report a case of follicular carcinoma in a 48-year-old female that demonstrates microfollicles which are larger in size and contain more number of follicular cells in cytologic smears (20-29 cells) in contrary to the literature definition of microfollicles containing approximately 6-12 cells. We also demonstrate absence of basement membranes in these microfollicles in histologic sections by Silver Methanamine Stain, which may be an indicator to search for vascular and capsular invasion. This case report also describes postoperative positron emission tomography scan findings.

Results of 188 Whole-Body Fluorodeoxyglucose Positron Emission Tomography Scans in 137 Patients With Sarcoidosis

To study the role of whole-body 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) scans in the identification of occult biopsy sites and reversible granulomatous disease in patients with sarcoidosis. A retrospective review was undertaken of 188 FDG PET scans performed in 137 patients with proven sarcoidosis. All patients had given a complete medical history and undergone a physical examination, standard chest radiograph, spirometry, diffusing capacity determination, and measurement of serum angiotensin-converting enzymes levels. One hundred thirty-nine whole-body scans had positive findings. The most common positive sites were mediastinal lymph nodes (54 scans), extrathoracic lymph nodes (30 scans), and lung (24 scans). The standardized uptake value (SUV) ranged from 2.0 to 15.8. Twenty occult disease sites were identified. Eleven repeat scans exhibited decreased SUV with corticosteroid therapy. The positive pulmonary FDG PET scan findings occurred in two thirds of patients with radiographic stage II and III sarcoidosis. Negative pulmonary FDG PET scan findings were common in patients with radiographic stage 0, I, and IV sarcoidosis. Whole-body FDG PET scans are of value in identifying occult and reversible granulomas in patients with sarcoidosis. However, a positive FDG PET scan finding, by itself, is not an indication for treatment.

F-18 fluorodeoxy-D-glucose positron emission tomography scan in the initial evaluation of patients with a primary melanoma thicker than 4 mm

Metabolic imaging with F-18 fluorodeoxy-D-glucose positron emission tomography is one of the most sensitive and non-invasive techniques, and has proved useful in melanoma. We designed, in 2004, at the Institute Gustave Roussy, a prospective study to determine the value of F-18 fluorodeoxy-D-glucose positron emission tomography scanning in the detection of regional and/or distant metastasis in 25 new patients referred for the treatment of a primary melanoma thicker than 4 mm (tumor node metastases stage T4). The sentinel lymph node biopsy was proposed for all the patients without a palpable regional lymph node. Abnormal positron emission tomography scan findings were correlated to available histological data and to the course of the disease. The F-18 fluorodeoxy-D-glucose positron emission tomography scan identified 0/2 intact primary melanomas, 1/4 residual primary melanomas after limited excision, 0/6 lymph node basins with micrometastasis, 4/4 lymph node basins with enlarged palpable lymph nodes and 0 distant metastasis. The sensitivity and specificity of positron emission tomography scans for microscopic lymph node disease in basins were, respectively, 0 and 92%. A false-positive F-18 fluorodeoxy-D-glucose positron emission tomography result in a cervical basin led to a useless cervical lymph node dissection. In three patients, the positron emission tomography scan was positive in distant sites but none of these foci represented a true metastasis. In conclusion, it is not useful to include a positron emission tomography scan in the initial work-up of patients with primary melanoma, even in patients with thick primary melanomas (>4 mm). Sentinel lymph node biopsy remains the technique of choice for the most accurate initial staging.

EUS with Or Without FNA Is a Highly Effective Modality in Evaluation of Positive PET Scan Findings

Background: Positron emission tomography (PET) is commonly employed to detect distant metastatic disease in patients with known or suspected cancer. When the PET demonstrates uptake near the esophagus, stomach, duodenum, or rectum, EUS can be used to evaluate these areas to confirm or exclude malignant disease. The effectiveness of EUS for this indication is not known. The aim of this study was to evaluate the impact of EUS with or without FNA on the clinical management of patients with positive PET scans.

Utility of PET scans to predict disease relapse in pediatric patients with Hodgkin lymphoma

Positron emission tomography (PET) differentiates normal from abnormal cells based on metabolic activity. Numerous studies report that PET scan offers increased sensitivity, specificity and predictive values as compared to computed tomography (CT) in adult lymphoma patients. Twenty-three consecutive pediatric Hodgkin lymphoma (HL) patients were evaluated with PET scan either at diagnosis or during treatment, then at therapy completion and in follow-up. Twenty two of the 23 patients had a negative PET scan at the end of therapy; however, ten later developed a positive scan for a total of 11 (47.8%) patients with a positive post treatment PET scan. Six tissue biopsies were performed in five patients; four specimens were negative for disease and two confirmed HL relapse. Six patients were monitored clinically and remained asymptomatic; four had resolution of abnormalities on repeat PET while two had persistently positive, but stable PET scan findings and continue to be in remission at 11 and 40 months following treatment. Twelve (52.2%) patients of the original cohort have had consistently negative PET scans and have not relapsed. PET is a sensitive (100%), but not a specific (57.1%) method for evaluating post-treatment pediatric HL patients with a strong negative predictive value (NPV; 100%), but poor positive predictive value (PPV; 18.2%). We do not recommend treatment decisions be based solely on PET scan results.

18F]Fluorodeoxyglucose Uptake by Positron Emission Tomography for Diagnosis of Suspected Lung Cancer

Verification bias occurs when test findings influence the decision to perform a gold standard test. It adversely influences diagnostic test accuracy by inflating sensitivity and deflating specificity. We studied the impact of verification bias on the estimated accuracy of a test commonly used in suspected lung cancer. We studied 534 consecutive patients referred for [(18)F]fluorodeoxyglucose uptake by positron emission tomography (PET). Primary outcomes were tissue diagnoses of cancer and of mediastinal lymph node metastases. A secondary outcome was 3-year mortality. We accounted for verification bias using 2 validated methods. The gold standard test, namely tissue acquisition, was performed in 419 patients (78%); mediastinal lymph node sampling occurred in 301 (56%). While the 410 patients with PET-diagnosed stage I cancer or higher were more likely than patients with negative PET scan findings to undergo tissue diagnosis testing (92% vs 34%) (P<.001), there was no association between PET findings and performance of mediastinal sampling. Without accounting for verification bias, the sensitivity and specificity of PET for diagnosis of cancer were 0.95 (95% confidence interval [CI], 0.92-0.97) and 0.31 (95% CI, 0.21-0.42), respectively. After adjustment, sensitivity fell to 0.85 (95% CI, 0.81-0.89), while specificity increased to 0.51 (95% CI, 0.40-0.60). For diagnosis of mediastinal disease, verification bias had slight effects on test accuracy. There were 224 deaths, with a strong gradient between PET stage and death (P<.001). The diagnostic accuracy of PET for assessment of suspected lung cancer is substantially affected by verification bias.

Congenital Perisylvian Syndrome: MRI and Glucose PET Correlations

Congenital perisylvian syndromes are late migration/cortical organization disorders associated with distinctive clinical and imaging features. The clinical, magnetic resonance imaging, and 2-deoxy-2-[18F] fluoro-D-glucose (FDG) positron emission tomography scan findings of six children (age range: 3.2-16.7 years; 5 males) with congenital perisylvian syndrome were evaluated. The patients presented with heterogenous neurologic impairments, depending upon the involved hemisphere and the extension of perisylvian malformation. Two manifested bilateral malformation and four manifested unilateral. The characteristic MRI finding consisting of a vertically oriented sylvian fissure continuous with the central and postcentral sulcus was associated with variable extension of bordering polymicrogyric cortex. The positron emission tomography scans of all patients revealed perisylvian metabolic abnormalities corresponding to the magnetic resonance imaging-defined abnormality. Variable extent of abnormal glucose metabolism was also observed in areas with normal magnetic resonance imaging features. All patients with unilateral magnetic resonance imaging abnormality exhibited abnormal glucose metabolism also in the contralateral side. The two patients with bilateral malformation had more extensive positron emission tomography abnormalities than the morphologic anomalies on MRI. Although MRI remains the diagnostic gold standard to detect the lesion, positron emission tomography scan is helpful to evaluate the full functional extension of the cortical anomaly, thereby contributing to the definition of the clinical severity of the syndrome.