Positive Positron Emission Tomography Results Research Articles

Unanticipated pathological clearance in two cases of clinical T4b dMMR/MSI-h advanced colorectal cancer: the potential of immune checkpoint inhibitors despite positive positron-emission tomography results.

The standard treatment for colorectal cancer consists of surgery and chemotherapy, which can be combined to improve outcomes. Immune checkpoint inhibitors (ICI) are a significant advancement in the standard treatment of metastatic, unresectable colorectal cancer with deficient mismatch repair (dMMR). However, limited data are available about the use of ICI in the neoadjuvant and conversion settings. Here, we present two cases treated with ICI. Case 1: A 75-year-old male with a large, borderline resectable rectal cancer diagnosed as cT4bN1bM0 who underwent neoadjuvant chemotherapy, followed by combination ICI consisting of ipilimumab and nivolumab. After four courses of ICI, the tumor significantly shrank, but positron emission tomography still showed a positive result and R0 resection was performed. Pathological analysis revealed no residual cancer cells. The patient has been monitored without adjuvant chemotherapy, and no recurrences have occurred after one year. Case 2: A 60-year-old male with locally advanced sigmoid colon cancer who received neoadjuvant treatment with pembrolizumab. The tumor partially shrank after three courses, and continued pembrolizumab monotherapy resulted in further tumor shrinkage which still showed positive positron emission tomography. Curative sigmoidectomy with partial resection of the ileum and bladder was performed, and the pathological outcome was pCR. There was no viable tumor in the specimen. The patient has been monitored without adjuvant chemotherapy for six months, and no recurrence has been observed. The present study reports two cases, including a large, borderline resectable rectal cancer after failure of chemotherapy followed by combination treatment with nivolumab and ipilimumab and one case of sigmoid colon cancer after pembrolizumab treatment, which resulted in pathological complete response. However, it remains unknown whether ICI therapy can replace surgery or diminish the optimal extent of resection, or whether adjuvant chemotherapy is needed after surgery in the case of achieving pCR after ICI therapy. Overall, this case report suggests that ICI before colorectal surgery can be effective and potentially a 'watch-and-wait" strategy could be used for cases in which ICI is effective.

Amyloid Positron Emission Tomography and Subsequent Health Care Use Among Medicare Beneficiaries With Mild Cognitive Impairment or Dementia

Results of amyloid positron emission tomography (PET) have been shown to change the management of patients with mild cognitive impairment (MCI) or dementia who meet Appropriate Use Criteria (AUC). To determine if amyloid PET is associated with reduced hospitalizations and emergency department (ED) visits over 12 months in patients with MCI or dementia. This nonrandomized controlled trial analyzed participants in the Imaging Dementia-Evidence for Amyloid Scanning (IDEAS) study, an open-label, multisite, longitudinal study that enrolled participants between February 2016 and December 2017 and followed up through December 2018. These participants were recruited at 595 clinical sites that provide specialty memory care across the US. Eligible participants were Medicare beneficiaries 65 years or older with a diagnosis of MCI or dementia within the past 24 months who met published AUC for amyloid PET. Each IDEAS study participant was matched to a control Medicare beneficiary who had not undergone amyloid PET. Data analysis was conducted on December 13, 2022. Participants underwent amyloid PET at imaging centers. The primary end points were the proportions of patients with 12-month inpatient hospital admissions and ED visits. One of 4 secondary end points was the rate of hospitalizations and rate of ED visits in participants with positive vs negative amyloid PET results. Health care use was ascertained from Medicare claims data. The 2 cohorts (IDEAS study participants and controls) each comprised 12 684 adults, including 6467 females (51.0%) with a median (IQR) age of 77 (73-81) years. Over 12 months, 24.0% of the IDEAS study participants were hospitalized, compared with 25.1% of the matched control cohort, for a relative reduction of -4.49% (97.5% CI, -9.09% to 0.34%). The 12-month ED visit rates were nearly identical between the 2 cohorts (44.8% in both IDEAS study and control cohorts) for a relative reduction of -0.12% (97.5% CI, -3.19% to 3.05%). Both outcomes fell short of the prespecified effect size of 10% or greater relative reduction. Overall, 1467 of 6848 participants (21.4%) with positive amyloid PET scans were hospitalized within 12 months compared with 1081 of 4209 participants (25.7%) with negative amyloid PET scans (adjusted odds ratio, 0.83; 95% CI, 0.78-0.89). Results of this nonrandomized controlled trial showed that use of amyloid PET was not associated with a significant reduction in 12-month hospitalizations or ED visits. Rates of hospitalization were lower in patients with positive vs negative amyloid PET results.

Evaluation of Plasma Phosphorylated Tau217 for Differentiation Between Alzheimer Disease and Frontotemporal Lobar Degeneration Subtypes Among Patients With Corticobasal Syndrome

Plasma phosphorylated tau217 (p-tau217), a biomarker of Alzheimer disease (AD), is of special interest in corticobasal syndrome (CBS) because autopsy studies have revealed AD is the driving neuropathology in up to 40% of cases. This differentiates CBS from other 4-repeat tauopathy (4RT)-associated syndromes, such as progressive supranuclear palsy Richardson syndrome (PSP-RS) and nonfluent primary progressive aphasia (nfvPPA), where underlying frontotemporal lobar degeneration (FTLD) is typically the primary neuropathology. To validate plasma p-tau217 against positron emission tomography (PET) in 4RT-associated syndromes, especially CBS. This multicohort study with 6, 12, and 24-month follow-up recruited adult participants between January 2011 and September 2020 from 8 tertiary care centers in the 4RT Neuroimaging Initiative (4RTNI). All participants with CBS (n = 113), PSP-RS (n = 121), and nfvPPA (n = 39) were included; other diagnoses were excluded due to rarity (n = 29). Individuals with PET-confirmed AD (n = 54) and PET-negative cognitively normal control individuals (n = 59) were evaluated at University of California San Francisco. Operators were blinded to the cohort. Plasma p-tau217, measured by Meso Scale Discovery electrochemiluminescence, was validated against amyloid-β (Aβ) and flortaucipir (FTP) PET. Imaging analyses used voxel-based morphometry and bayesian linear mixed-effects modeling. Clinical biomarker associations were evaluated using longitudinal mixed-effect modeling. Of 386 participants, 199 (52%) were female, and the mean (SD) age was 68 (8) years. Plasma p-tau217 was elevated in patients with CBS with positive Aβ PET results (mean [SD], 0.57 [0.43] pg/mL) or FTP PET (mean [SD], 0.75 [0.30] pg/mL) to concentrations comparable to control individuals with AD (mean [SD], 0.72 [0.37]), whereas PSP-RS and nfvPPA showed no increase relative to control. Within CBS, p-tau217 had excellent diagnostic performance with area under the receiver operating characteristic curve (AUC) for Aβ PET of 0.87 (95% CI, 0.76-0.98; P < .001) and FTP PET of 0.93 (95% CI, 0.83-1.00; P < .001). At baseline, individuals with CBS-AD (n = 12), defined by a PET-validated plasma p-tau217 cutoff 0.25 pg/mL or greater, had increased temporoparietal atrophy at baseline compared to individuals with CBS-FTLD (n = 39), whereas longitudinally, individuals with CBS-FTLD had faster brainstem atrophy rates. Individuals with CBS-FTLD also progressed more rapidly on a modified version of the PSP Rating Scale than those with CBS-AD (mean [SD], 3.5 [0.5] vs 0.8 [0.8] points/year; P = .005). In this cohort study, plasma p-tau217 had excellent diagnostic performance for identifying Aβ or FTP PET positivity within CBS with likely underlying AD pathology. Plasma P-tau217 may be a useful and inexpensive biomarker to select patients for CBS clinical trials.

P008: Impact of bone marrow involvement on early PET response and progression-free survival in the HD18 trial for patients with advanced-stage Hodgkin lymphoma

Background: The prognostic role of bone marrow (BM) involvement in advanced-stage Hodgkin lymphoma is unclear, particularly for patients receiving intensive first-line treatment. We thus retrospectively examined its impact on early response and progression-free survival (PFS) among individuals receiving escalated bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine, and prednisone (eBEACOPP) in the HD18 trial. Patients and Methods: A total of 424 individuals were suitable for analysis, of which 124 (29%) had BM involvement according to initial positron emission tomography (PET). Patient outcome was measured by PET response after 2×eBEACOPP and five-year PFS rate. Results: After 2×eBEACOPP, 79 of the BM PET-negative individuals (26%) and 26 of the BM PET-positive patients (21%) were found to be PET-positive (odds ratio [OR] 0.74, P=0.25). The five-year PFS rate was 90.7% in BM PET-negative individuals and 91.8% for BM PET-positive patients (hazard ratio 0.82, P=0.6). In our BM PET-positive subgroup, nine (16%) of the 56 subjects with one or two sites of skeletal uptake were PET-positive after 2×eBEACOPP as compared to 17 (25%) of the 68 individuals showing three or more BM lesions (OR 1.74, P=0.23). Conclusions: The present analysis demonstrates that BM involvement, irrespective of its extent, does not lead to increased risk for a positive interim PET result or inferior PFS in advanced-stage Hodgkin lymphoma patients undergoing eBEACOPP treatment. Skeletal lesions cannot therefore be considered as an additional prognostic marker of therapy failure or disease recurrence for individuals receiving intensive first-line treatment.

Association of Amyloid Positron Emission Tomography With Changes in Diagnosis and Patient Treatment in an Unselected Memory Clinic Cohort

Previous studies have evaluated the diagnostic effect of amyloid positron emission tomography (PET) in selected research cohorts. However, these research populations do not reflect daily practice, thus hampering clinical implementation of amyloid imaging. To evaluate the association of amyloid PET with changes in diagnosis, diagnostic confidence, treatment, and patients' experiences in an unselected memory clinic cohort. Amyloid PET using fluoride-18 florbetaben was offered to 866 patients who visited the tertiary memory clinic at the VU University Medical Center between January 2015 and December 2016 as part of their routine diagnostic dementia workup. Of these patients, 476 (55%) were included, 32 (4%) were excluded, and 358 (41%) did not participate. To enrich this sample, 31 patients with mild cognitive impairment from the University Medical Center Utrecht memory clinic were included. For each patient, neurologists determined a preamyloid and postamyloid PET diagnosis that existed of both a clinical syndrome (dementia, mild cognitive impairment, or subjective cognitive decline) and a suspected etiology (Alzheimer disease [AD] or non-AD), with a confidence level ranging from 0% to 100%. In addition, the neurologist determined patient treatment in terms of ancillary investigations, medication, and care. Each patient received a clinical follow-up 1 year after being scanned. Primary outcome measures were post-PET changes in diagnosis, diagnostic confidence, and patient treatment. Of the 507 patients (mean [SD] age, 65 (8) years; 201 women [39%]; mean [SD] Mini-Mental State Examination score, 25 [4]), 164 (32%) had AD dementia, 70 (14%) non-AD dementia, 114 (23%) mild cognitive impairment, and 159 (31%) subjective cognitive decline. Amyloid PET results were positive for 242 patients (48%). The suspected etiology changed for 125 patients (25%) after undergoing amyloid PET, more often due to a negative (82 of 265 [31%]) than a positive (43 of 242 [18%]) PET result (P < .01). Post-PET changes in suspected etiology occurred more frequently in patients older (>65 years) than younger (<65 years) than the typical age at onset of 65 years (74 of 257 [29%] vs 51 of 250 [20%]; P < .05). Mean diagnostic confidence (SD) increased from 80 (13) to 89 (13%) (P < .001). In 123 patients (24%), there was a change in patient treatment post-PET, mostly related to additional investigations and therapy. This prospective diagnostic study provides a bridge between validating amyloid PET in a research setting and implementing this diagnostic tool in daily clinical practice. Both amyloid-positive and amyloid-negative results had substantial associations with changes in diagnosis and treatment, both in patients with and without dementia.

Abstract #230: A Shot in the Dark: False Positive Positron Emission Tomography Results with Once Weekly Exenatide and 18-Fluoro-2- Deoxyglucose

Abstract #230: A Shot in the Dark: False Positive Positron Emission Tomography Results with Once Weekly Exenatide and 18-Fluoro-2- Deoxyglucose

Prognostic value of pre- and post-transplantation 18F-fluorodeoxyglucose positron emission tomography results in non-Hodgkin lymphoma patients receiving autologous stem cell transplantation.

High-dose chemotherapy (HDC) followed by autologous stem cell transplantation (ASCT) is the standard of care in the upfront or relapsed/refractory setting in some patients with non-Hodgkin lymphoma (NHL). However, a proportion of patients do not respond to ASCT. 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) has been widely used for staging, response evaluation, and prognosis prediction. Here, we investigated the prognostic role of PET/CT in NHL patients before and after ASCT. A retrospective study was conducted at Peking University Cancer Hospital. All NHL patients who underwent ASCT between March 2010 and July 2016 were identified. Patients who had PET/CT scan before and after ASCT were included. Deauville criteria (5-point scale) were used to interpret PET scans. Univariate and multivariate survival analyses were performed using Cox regression. The predictive value of PET scanning was estimated by comparing the area under the receiver operating characteristic (ROC) curve. In total, 79 patients were enrolled in this study. In univariate analysis, pre- and post-ASCT PET result was identified as prognostic factors for 3-year progression-free survival (PFS) and overall survival (OS). Patients with negative pre-ASCT PET result demonstrated significantly better PFS (84.2% vs. 54.2%) and OS (89.2% vs. 63.6%) than patients with positive pre-ASCT PET result. PFS (91.6% vs. 25.3%) and OS (96.5% vs. 36.8%) were also significantly different between patients with negative and positive post-ASCT PET result. Multivariate analysis also showed a significant association between survival and post-ASCT PET result. ROC analysis revealed that the predictive value of post-ASCT PET result was superior to that of pre-ASCT PET result alone. Combined pre- and post-ASCT PET result is better for predicting outcomes in patients with NHL receiving transplantation. Deauville criteria score >3 was identified as the best cutoff value for post-ASCT PET. Post-ASCT PET result was more important than pre-ASCT PET result in predicting outcomes for NHL patients who underwent ASCT. The prognostic significance can be improved when combining pre-ASCT PET result with post-ASCT PET result. Deauville criteria can be used for interpreting PET scans in this scenario.

Diagnostic accuracy of 18F-FDG PET/CT for detection of advanced colorectal adenoma

To determine the accuracy of 2-[(18)F]-fluoro-2-deoxy-d-glucose (FDG) positron-emission tomography (PET) in the detection of advanced colorectal adenomas. In this retrospective study, patient consent was waived by the institutional review board. Combined FDG whole-body PET and computed tomography (CT) images (2000-2009) were re-read and compared with reports of complete colonoscopy performed up to 1 year after the PET examination. One or more areas of focal colonic uptake greater than the background indicated a positive PET result, irrespective of standardized uptake value (SUV). Lesion and patient-level measures of PET accuracy with their 95% confidence intervals (CI) were calculated. One hundred and eighty patients undergoing colonoscopy with or without biopsy underwent PET within 1 year prior to colonoscopy. There were 92 women and 88 men (mean age 63.3 years). Indications for PET were extent of disease and treatment response in all cases. Patients had non-colorectal cancer (n = 160) or colon cancer (n = 20). One hundred and fourteen FDG-avid lesions were present. In 33, there was no colonoscopic correlate. Two hundred and fifty-eight biopsies revealed tubular adenomas (n = 91, one with intra-mucosal cancer), tubulovillous adenomas (n = 28), adenocarcinoma (n = 37), inflammation (n = 22), hyperplastic polyps (n = 54), serrated adenoma (n = 5), metastatic disease (n = 5), normal/benign mucosa or submucosal benign tumors (n = 13) or miscellaneous (n = 3). Per-lesion performance of PET showed a sensitivity of 38% (95% CI: 31-46; 64/167) for all adenomas and carcinomas and 58% (95% CI: 49-67; 57/98) for lesions ≥ 10 mm. At the patient level, for all adenomas and carcinomas the sensitivity was 54% (95% CI: 44-63; 61/113), specificity 100% (pre-defined), positive predictive value (PPV) 100% (pre-defined), and negative predictive value (NPV) 56% (95% CI: 47-65; 67/119). For patients with advanced adenoma, PET sensitivity was 49% (95% CI: 35-63; 26/53) specificity, 100%, PPV 100% and NPV 82% (95% CI: 76-88; 127/154). Five of 37 adenocarcinomas were not detected, one of which was mucinous at histology. FDG PET detected most cancers, but only identified one-half of patients harbouring advanced adenomas. Based on the data, PET cannot be relied upon to accurately identify patients with advanced adenoma.

Hemangioma de mama simulando metástase no PET-CT

Hemangioma de mama é um tumor benigno raro que apresenta pouca ou nenhuma captação de 18F-flúor-2-deoxi-Dglicose (FDG) na tomografia por emissão de pósitrons (PET). Relatamos um nódulo mamário compatível, patologicamente, com hemangioma, em uma mulher cuja PET scan demonstrou captação elevada de FDG (simulando tumor maligno). Também fizemos breve revisão das causas que levam a resultados falso-positivos e falso-negativos pela PET.

Can positron emission tomography with the dual tracers [11C]acetate and [18F]fludeoxyglucose predict microvascular invasion in hepatocellular carcinoma?

Microvascular invasion is a poor prognostic indicator of the recurrence of hepatocellular carcinoma (HCC) after surgical treatment. Positron emission tomography (PET) with [(18) F]fludeoxyglucose ([(18) F]FDG) as a tracer has been employed to predict the prognosis before surgery for various kinds of tumors, but it has not been found to be sensitive enough for HCC. Thus, [(11) C]acetate has been adopted as an additional tracer. This study was designed to evaluate the ability of dual-tracer PET ([(18) F]FDG and [(11) C]acetate) to predict microvascular invasion before liver resection or transplantation. Fifty-eight HCC patients who were preoperatively examined with whole-body dual-tracer PET were studied. Twenty-five patients were [(18) F]FDG-positive, and 56 were [(11) C]acetate-positive. The sensitivity of [(18) F]FDG in detecting primary HCC was 43%, and the sensitivity of [(11) C]acetate was 93%. Twenty-nine patients had HCC with microvascular invasion according to the final pathological examination. The sensitivity, specificity, positive predictive value, and negative predictive value of [(18) F]FDG PET in predicting microvascular invasion were 55.2%, 69%, 64%, and 60.6%, respectively; the corresponding rates for [(11) C]acetate PET were 93.1%, 0%, 48.2%, and 0%. The factors associated with HCC recurrence, which included multifocal involvement, a large tumor size, microsatellite lesions, poor HCC differentiation, and an advanced stage of disease, were analyzed and compared with positive PET results. A tumor size greater than 5 cm was significantly associated with positive [(18) F]FDG PET results; [(11) C]acetate was not associated with poor prognostic indicators. Preoperative [(18) F]FDG PET may predict microvascular invasion. The addition of [(11) C]acetate improves the overall sensitivity of PET, but it has no incremental value in predicting microvascular invasion.

Restaging by Endobronchial Ultrasound-guided Transbronchial Needle Aspiration in Patients with Inoperable Advanced Lung Cancer

We present two cases of inoperable advanced lung cancer in which the main lesions were mediastinal lymph nodes detected with positive positron emission tomography (PET). Drug therapy was very effective, and post-treatment PET results were negative. Restaging by endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) was performed on the mediastinal lymph nodes with a short axis < or = 10 mm measured by computed tomography (CT). Cancer cells were detected, which helped determine the therapeutic strategy. Re-evaluation of mediastinal lymph nodes using EBUS-TBNA appears to be useful, even among patients with inoperable advanced lung cancer.

2100 The role of 18F-FDG PET in detection of biliary tract cancer recurrence during surveillance: A single center observational study

To determine the accuracy of 2-[18F]-fluoro-2-deoxy-d-glucose (FDG) positron-emission tomography (PET) in the detection of advanced colorectal adenomas.In this retrospective study, patient consent was waived by the institutional review board. Combined FDG whole-body PET and computed tomography (CT) images (2000–2009) were re-read and compared with reports of complete colonoscopy performed up to 1 year after the PET examination. One or more areas of focal colonic uptake greater than the background indicated a positive PET result, irrespective of standardized uptake value (SUV). Lesion and patient-level measures of PET accuracy with their 95% confidence intervals (CI) were calculated.One hundred and eighty patients undergoing colonoscopy with or without biopsy underwent PET within 1 year prior to colonoscopy. There were 92 women and 88 men (mean age 63.3 years). Indications for PET were extent of disease and treatment response in all cases. Patients had non-colorectal cancer (n = 160) or colon cancer (n = 20). One hundred and fourteen FDG-avid lesions were present. In 33, there was no colonoscopic correlate. Two hundred and fifty-eight biopsies revealed tubular adenomas (n = 91, one with intra-mucosal cancer), tubulovillous adenomas (n = 28), adenocarcinoma (n = 37), inflammation (n = 22), hyperplastic polyps (n = 54), serrated adenoma (n = 5), metastatic disease (n = 5), normal/benign mucosa or submucosal benign tumors (n = 13) or miscellaneous (n = 3). Per-lesion performance of PET showed a sensitivity of 38% (95% CI: 31–46; 64/167) for all adenomas and carcinomas and 58% (95% CI: 49–67; 57/98) for lesions ≥10 mm. At the patient level, for all adenomas and carcinomas the sensitivity was 54% (95% CI: 44–63; 61/113), specificity 100% (pre-defined), positive predictive value (PPV) 100% (pre-defined), and negative predictive value (NPV) 56% (95% CI: 47–65; 67/119). For patients with advanced adenoma, PET sensitivity was 49% (95% CI: 35–63; 26/53) specificity, 100%, PPV 100% and NPV 82% (95% CI: 76–88; 127/154). Five of 37 adenocarcinomas were not detected, one of which was mucinous at histology.FDG PET detected most cancers, but only identified one-half of patients harbouring advanced adenomas. Based on the data, PET cannot be relied upon to accurately identify patients with advanced adenoma.

Occult Malignancy in Patients With Suspected Paraneoplastic Neurologic Syndromes: Value of Positron Emission Tomography in Diagnosis

OBJECTIVE To determine the value of positron emission tomography (PET) in diagnosing occult malignancies in patients with paraneoplastic neurologic syndromes (PNSs) at Mayo Clinic's site in Rochester, MN. PATIENTS AND METHODS We retrospectively reviewed the medical charts of all 107 patients who underwent PET from January 1, 2000, to July 31, 2006, for the indication of suspected PNS. Three patients did not meet inclusion criteria. PET results were considered positive if increased fludeoxyglucose F 18 uptake indicated malignancy (24 patients). Results from computed tomography were interpreted as positive if any suspect lesion was consistent with malignancy (26 patients). RESULTS One hundred four patients with PNS were identified from the PET central database; 73 patients had at least 1 positive result for paraneoplastic antibody, and 31 had antibody-negative PNS. Malignancy was confirmed pathologically in 10 patients, of whom 8 had positive PET results. There were 2 cases of confirmed malignancy (fallopian tube adenocarcinoma and spindle cell uterine carcinoma) for which PET results were negative. Two patients with positive PET results declined biopsy. Computed tomography was able to identify 3 of the 10 malignancies detected. Five cases of malignancy were detected only by PET. All patients with confirmed malignancy had positive results for at least 1 paraneoplastic antibody. One patient with positive results for PNS antibody and negative PET results was diagnosed as having small cell carcinoma on a follow-up PET scan after 27 months. PET had sensitivity, specificity, positive predictive value, and negative predictive value of 80%, 67%, 53%, and 88%, respectively. CONCLUSION PET scan was shown to be more sensitive than computed tomography for detecting occult malignancy (confirmed by positive test results for autoantibody) among patients with suspected PNS. The greatest clinical utility of PET could be in its high negative predictive value. To determine the value of positron emission tomography (PET) in diagnosing occult malignancies in patients with paraneoplastic neurologic syndromes (PNSs) at Mayo Clinic's site in Rochester, MN. We retrospectively reviewed the medical charts of all 107 patients who underwent PET from January 1, 2000, to July 31, 2006, for the indication of suspected PNS. Three patients did not meet inclusion criteria. PET results were considered positive if increased fludeoxyglucose F 18 uptake indicated malignancy (24 patients). Results from computed tomography were interpreted as positive if any suspect lesion was consistent with malignancy (26 patients). One hundred four patients with PNS were identified from the PET central database; 73 patients had at least 1 positive result for paraneoplastic antibody, and 31 had antibody-negative PNS. Malignancy was confirmed pathologically in 10 patients, of whom 8 had positive PET results. There were 2 cases of confirmed malignancy (fallopian tube adenocarcinoma and spindle cell uterine carcinoma) for which PET results were negative. Two patients with positive PET results declined biopsy. Computed tomography was able to identify 3 of the 10 malignancies detected. Five cases of malignancy were detected only by PET. All patients with confirmed malignancy had positive results for at least 1 paraneoplastic antibody. One patient with positive results for PNS antibody and negative PET results was diagnosed as having small cell carcinoma on a follow-up PET scan after 27 months. PET had sensitivity, specificity, positive predictive value, and negative predictive value of 80%, 67%, 53%, and 88%, respectively. PET scan was shown to be more sensitive than computed tomography for detecting occult malignancy (confirmed by positive test results for autoantibody) among patients with suspected PNS. The greatest clinical utility of PET could be in its high negative predictive value.

Occult Malignancy in Patients With Suspected Paraneoplastic Neurologic Syndromes: Value of Positron Emission Tomography in Diagnosis

To determine the value of positron emission tomography (PET) in diagnosing occult malignancies in patients with paraneoplastic neurologic syndromes (PNSs) at Mayo Clinic's site in Rochester, MN. We retrospectively reviewed the medical charts of all 107 patients who underwent PET from January 1, 2000, to July 31, 2006, for the indication of suspected PNS. Three patients did not meet inclusion criteria. PET results were considered positive if increased fludeoxyglucose F 18 uptake indicated malignancy (24 patients). Results from computed tomography were interpreted as positive if any suspect lesion was consistent with malignancy (26 patients). One hundred four patients with PNS were identified from the PET central database; 73 patients had at least 1 positive result for paraneoplastic antibody, and 31 had antibody-negative PNS. Malignancy was confirmed pathologically in 10 patients, of whom 8 had positive PET results. There were 2 cases of confirmed malignancy (fallopian tube adenocarcinoma and spindle cell uterine carcinoma) for which PET results were negative. Two patients with positive PET results declined biopsy. Computed tomography was able to identify 3 of the 10 malignancies detected. Five cases of malignancy were detected only by PET. All patients with confirmed malignancy had positive results for at least 1 paraneoplastic antibody. One patient with positive results for PNS antibody and negative PET results was diagnosed as having small cell carcinoma on a follow-up PET scan after 27 months. PET had sensitivity, specificity, positive predictive value, and negative predictive value of 80%, 67%, 53%, and 88%, respectively. PET scan was shown to be more sensitive than computed tomography for detecting occult malignancy (confirmed by positive test results for autoantibody) among patients with suspected PNS. The greatest clinical utility of PET could be in its high negative predictive value.

Positron Emission Tomography Using 18F-Fluorodeoxyglucose for the Evaluation of Residual Hodgkin's Disease Mediastinal Masses

Given its obvious prognostic implications, the correct interpretation of the significance of any residual mediastinal mass following Hodgkin's disease (HD) treatment keeps maintaining its paramount importance. In this respect, 18F-fluorodeoxyglucose positron emission tomography (PET) is proving very effective for both active disease detection and relapse prediction. Twenty-nine consecutive HD patients, in whom computed tomography (CT) scan performed after therapy completion had documented a residual mediatinal mass of at least 2 cm, prospectively entered the study and underwent PET within 1 week from CT scan. With a median follow-up of 28 months from PET execution, no relapse was recorded among the 17 patients presenting with a negative PET. On the contrary, 9 of the 12 patients presenting with a positive PET relapsed/progressed within one year from PET execution. PET's negative and positive predictive values at 1 year were 100% and 75%, respectively. A negative PET seems to possibly exclude relapse in HD patient with a residual mediastinal mass. On the contrary, a positive PET result indicates a significantly higher risk of relapse. However, due to possible false positive results, a closer follow-up for all and a pathologic study in few selected patients is warranted.

Thoracic positron emission tomography using18F-fluorodeoxyglucose for the evaluation of residual mediastinal Hodgkin disease

Residual mediastinal masses are frequently observed in patients with Hodgkin disease (HD) after completed therapy, and the discrimination between active tumor tissue and fibrotic residues remains a clinical challenge. We studied the diagnostic value of metabolic imaging by 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) in detecting active mediastinal disease and predicting relapse. Twenty-eight HD patients with a residual mediastinal mass of at least 2 cm after initial therapy or after salvage chemotherapy were prospectively assigned to 29 examinations with FDG PET and were evaluated as 29 “subjects.” Patients were monitored for at least 1 year after examination and observed for signs of relapse. Median follow-up was 28 months (range, 16 to 68 months). A PET-negative mediastinal tumor was observed in 19 subjects, of whom 16 stayed in remission and 3 relapsed. Progression or relapse occurred in 6 of 10 subjects with a positive PET, whereas 4 subjects remained in remission. The negative predictive value (negative PET result and remission) at 1 year was 95%, and the positive predictive value (positive PET result and relapse) was 60%. The disease-free survival for PET-negative and PET-positive patients at 1 year was 95% and 40%, respectively. The difference was statistically significant. A negative FDG PET indicates that an HD patient with a residual mediastinal mass is unlikely to relapse before 1 year, if ever. On the other hand, a positive PET result indicates a significantly higher risk of relapse and demands further diagnostic procedures and a closer follow-up.

Thoracic positron emission tomography using18F-fluorodeoxyglucose for the evaluation of residual mediastinal Hodgkin disease

AbstractResidual mediastinal masses are frequently observed in patients with Hodgkin disease (HD) after completed therapy, and the discrimination between active tumor tissue and fibrotic residues remains a clinical challenge. We studied the diagnostic value of metabolic imaging by 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) in detecting active mediastinal disease and predicting relapse. Twenty-eight HD patients with a residual mediastinal mass of at least 2 cm after initial therapy or after salvage chemotherapy were prospectively assigned to 29 examinations with FDG PET and were evaluated as 29 “subjects.” Patients were monitored for at least 1 year after examination and observed for signs of relapse. Median follow-up was 28 months (range, 16 to 68 months). A PET-negative mediastinal tumor was observed in 19 subjects, of whom 16 stayed in remission and 3 relapsed. Progression or relapse occurred in 6 of 10 subjects with a positive PET, whereas 4 subjects remained in remission. The negative predictive value (negative PET result and remission) at 1 year was 95%, and the positive predictive value (positive PET result and relapse) was 60%. The disease-free survival for PET-negative and PET-positive patients at 1 year was 95% and 40%, respectively. The difference was statistically significant. A negative FDG PET indicates that an HD patient with a residual mediastinal mass is unlikely to relapse before 1 year, if ever. On the other hand, a positive PET result indicates a significantly higher risk of relapse and demands further diagnostic procedures and a closer follow-up.

Prognostic value of thoracic FDG PET imaging after treatment for non-small cell lung cancer.

We determined the prognostic value of 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) for patients with treated lung cancer. We examined patients who underwent FDG PET after first-line treatment for non-small cell lung cancer. FDG PET results were correlated with survival rates to determine whether FDG PET findings were predictive of outcomes. After initial therapy, 113 patients with non-small cell lung cancer underwent FDG PET. One hundred patients had positive FDG PET results and a median survival of 12 months (95% confidence interval, 9.2-15.4). Thirteen patients had negative FDG PET results, and 11 (85%) of these patients are still living at a median follow-up of 34 months. The difference in survival for patients with positive and negative FDG PET results was statistically significant (p = 0.002). FDG PET has prognostic value and strongly correlates with survival rates of patients with treated lung cancer. Patients with positive FDG PET results have a significantly worse prognosis than patients with negative results. Additionally, FDG PET may be helpful in guiding therapeutic treatments.

Whole-body 2-[18F]-fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET) for accurate staging of Hodgkin’s disease

Staging of Hodgkin's disease (HD) is accomplished by a variety of invasive and non-invasive modalities. This prospective study was undertaken to investigate the value of whole-body positron emission tomography (PET) with 2-[18F]-fluoro-2-deoxy-D-glucose (FDG) in defining regions involved by lymphoma compared with conventional staging methods in patients with HD. Fourty-four newly diagnosed patients with HD underwent FDG-PET as part of their initial staging work-up. PET findings were correlated with findings of conventional staging including computed tomography, ultrasound, bone scanning, bone marrow biopsy, liver biopsy and laparotomy. When results of FDG-PET differed to those obtained by conventional methods reevaluation was performed by biopsy, if possible, or magnetic resonance imaging. The results of FDG-PET were compared with three hundred twenty-one conventional staging procedures performed in 44 patients. FDG-PET was positive in 38 of 44 (86%) patients at sites of documented disease. PET detected additional lesions in five cases previously not identified by conventional staging methods. In another case a nodal lesion suspect on CT was negative at FDG-PET and was settled as true negative by biopsy. As a consequence of PET findings five patients had to be upstaged and one patient had to be downstaged, resulting in changes in treatment strategy in all six cases (14%). FDG-PET failed to visualize sites of HD in four patients. In two of our patients a false positive PET result was obtained. Our data indicate that FDG-PET provides an imaging technique that appears to visualize involved lesions in most patients with HD and is useful in the management of these patients.