Prospective use of serial questionnaires to evaluate the therapeutic efficacy of 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) in suspected lung cancer

The Prognostic Value of Positron Emission Tomography/Computed Tomography in Clinical Stage I Lung Cancer Patients: A Propensity-Match Analysis

Background: The application of positron emission tomography/computed tomography (PET/CT) helps provide accurate clinical staging for lung cancer patients. However, the effects and trends in early-stage lung cancer remain unclear. The aim of this study was to compare differences between clinical stage I lung cancer patients who received PET/CT for staging and those who did not. Methods: Data were obtained from the Taiwan Society of Cancer Registry. There were 6587 clinical stage I lung cancer patients between 2009 and 2014 analyzed in this study. We compared the characteristics of the PET/CT and no PET/CT groups. After propensity score matching, it resulted in both groups having 2649 patients. We measured the overall survival rates of all clinical stage I lung cancer patients and the overall survival rates of patients with PET/CT and without PET/CT. Results: The 1-, 3-, and 5-year survival rates of all clinical stage I lung cancer patients were 97.2%, 88.2%, and 79.0%, respectively. Patients with a larger tumor size tended to receive PET/CT for staging (stage Ib: 38.25% vs. 27.82%, p < 0.0001) and a larger resection (lobectomy: 74.62% vs. 66.61%, p < 0.0001). The 5-year survival rates were 79.8% in the PET/CT group and 78.2% in the no PET/CT group after propensity score matching (p = 0.6528). Conclusions: For clinical stage I lung cancer in Taiwan, patients with larger tumor sizes tend to have PET/CT for staging. Although PET/CT provided more precise clinical staging, these patients still received larger resections and had more pathological migration. However, there was no overall survival rate benefit after PET/CT.

Dynamic contrast-enhanced CT compared with positron emission tomography CT to characterise solitary pulmonary nodules: the SPUtNIk diagnostic accuracy study and economic modelling

BACKGROUND

Current pathways recommend positron emission tomography-computerised tomography for the characterisation of solitary pulmonary nodules. Dynamic contrast-enhanced computerised tomography may be a more cost-effective approach.

OBJECTIVES

To determine the diagnostic performances of dynamic contrast-enhanced computerised tomography and positron emission tomography-computerised tomography in the NHS for solitary pulmonary nodules. Systematic reviews and a health economic evaluation contributed to the decision-analytic modelling to assess the likely costs and health outcomes resulting from incorporation of dynamic contrast-enhanced computerised tomography into management strategies.

DESIGN

Multicentre comparative accuracy trial.

SETTING

Secondary or tertiary outpatient settings at 16 hospitals in the UK.

PARTICIPANTS

Participants with solitary pulmonary nodules of ≥ 8 mm and of ≤ 30 mm in size with no malignancy in the previous 2 years were included.

INTERVENTIONS

Baseline positron emission tomography-computerised tomography and dynamic contrast-enhanced computer tomography with 2 years' follow-up.

MAIN OUTCOME MEASURES

Primary outcome measures were sensitivity, specificity and diagnostic accuracy for positron emission tomography-computerised tomography and dynamic contrast-enhanced computerised tomography. Incremental cost-effectiveness ratios compared management strategies that used dynamic contrast-enhanced computerised tomography with management strategies that did not use dynamic contrast-enhanced computerised tomography.

RESULTS

A total of 380 patients were recruited (median age 69 years). Of 312 patients with matched dynamic contrast-enhanced computer tomography and positron emission tomography-computerised tomography examinations, 191 (61%) were cancer patients. The sensitivity, specificity and diagnostic accuracy for positron emission tomography-computerised tomography and dynamic contrast-enhanced computer tomography were 72.8% (95% confidence interval 66.1% to 78.6%), 81.8% (95% confidence interval 74.0% to 87.7%), 76.3% (95% confidence interval 71.3% to 80.7%) and 95.3% (95% confidence interval 91.3% to 97.5%), 29.8% (95% confidence interval 22.3% to 38.4%) and 69.9% (95% confidence interval 64.6% to 74.7%), respectively. Exploratory modelling showed that maximum standardised uptake values had the best diagnostic accuracy, with an area under the curve of 0.87, which increased to 0.90 if combined with dynamic contrast-enhanced computerised tomography peak enhancement. The economic analysis showed that, over 24 months, dynamic contrast-enhanced computerised tomography was less costly (£3305, 95% confidence interval £2952 to £3746) than positron emission tomography-computerised tomography (£4013, 95% confidence interval £3673 to £4498) or a strategy combining the two tests (£4058, 95% confidence interval £3702 to £4547). Positron emission tomography-computerised tomography led to more patients with malignant nodules being correctly managed, 0.44 on average (95% confidence interval 0.39 to 0.49), compared with 0.40 (95% confidence interval 0.35 to 0.45); using both tests further increased this (0.47, 95% confidence interval 0.42 to 0.51).

LIMITATIONS

The high prevalence of malignancy in nodules observed in this trial, compared with that observed in nodules identified within screening programmes, limits the generalisation of the current results to nodules identified by screening.

CONCLUSIONS

Findings from this research indicate that positron emission tomography-computerised tomography is more accurate than dynamic contrast-enhanced computerised tomography for the characterisation of solitary pulmonary nodules. A combination of maximum standardised uptake value and peak enhancement had the highest accuracy with a small increase in costs. Findings from this research also indicate that a combined positron emission tomography-dynamic contrast-enhanced computerised tomography approach with a slightly higher willingness to pay to avoid missing small cancers or to avoid a 'watch and wait' policy may be an approach to consider.

FUTURE WORK

Integration of the dynamic contrast-enhanced component into the positron emission tomography-computerised tomography examination and the feasibility of dynamic contrast-enhanced computerised tomography at lung screening for the characterisation of solitary pulmonary nodules should be explored, together with a lower radiation dose protocol.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42018112215 and CRD42019124299, and the trial is registered as ISRCTN30784948 and ClinicalTrials.gov NCT02013063.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 26, No. 17. See the NIHR Journals Library website for further project information.

Practice-based evidence for the clinical benefit of PET/CT-results of the first oncologic PET/CT registry in Germany

PURPOSE

The purpose of this study was to evaluate the impact of PET/CT on clinical management of cancer patients based on a prospective data registry. The study was developed to inform consultations with public health insurances on PET/CT coverage.

METHODS

We evaluated a prospective patient cohort having a clinically indicated PET/CT at a single German University Center from April 2013 to August 2016. The registry collected questionnaire data from requesting physicians on intended patient management before and after PET/CT. A total of 4,504 patients with 5,939 PET/CT examinations were enrolled in the registry, resulting in evaluable data from 3,724 patients receiving 4,754 scans. The impact of PET/CT on patient management was assessed across 22 tumor types, for different indications (diagnosis, staging, suspected recurrence) and different categories of management including treatment (curative or palliative) and non-treatment (watchful waiting, additional imaging, invasive tests).

RESULTS

The most frequent PET/CT indication was tumor staging (59.7%). Melanoma, lung cancer, lymphoma, neuroendocrine tumor and prostate cancer accounted for 70% of cases. Overall, the use of PET/CT resulted in a 37.1% change of clinical management (95% CI, 35.7-38.5), most frequently (30.6%) from an intended non-treatment strategy before PET/CT to active treatment after PET/CT. The frequency of changes ranged from 28.3% for head and neck cancers up to 46.0% for melanomas. The impact of PET/CT was greatest in reducing demands for additional imaging which decreased from 66.1% before PET/CT to 6.1% after PET/CT. Pre-PET/CT planned invasive tests could be avoided in 72.7% of cases. The treatment goal changed after PET/CT in 21.7% of cases, in twice as many cases from curative to palliative therapy than vice versa.

CONCLUSIONS

The data of this large prospective registry confirm that physicians often change their intended management on the basis of PET/CT by initiating treatment and reducing additional imaging as well as invasive tests. This applies to various cancer types and indications.

89Zr-trastuzumab PET supports clinical decision making in breast cancer patients, when HER2 status cannot be determined by standard work up

Background

Up-to-date information on human epidermal growth factor receptor 2 (HER2) status in breast cancer (BC) is important, as expression can vary during the course of the disease, necessitating anti-HER2 therapy adjustments. Repeat biopsies, however, are not always possible. In this feasibility trial we assessed whether ⁸⁹Zr-trastuzumab PET could support diagnostic understanding and aid clinical decision making, when HER2 status could not be determined by standard work up. Additionally, HER2 status on circulating tumour cells (CTCs) was assessed.

Patients and methods

⁸⁹Zr-trastuzumab PET was performed in patients if disease HER2 status remained unclear after standard work up (bone scan, ¹⁸F-FDG PET, CT and if feasible a biopsy). PET result and central pathologic revision of available tumour biopsies were reported to the referring physician. CTC HER2 status prior to PET was evaluated afterwards and therefore not reported. Diagnostic understanding and treatment decision questionnaires were completed by the referring physicians before, directly after and ≥ 3 months after ⁸⁹Zr-trastuzumab PET.

Results

Twenty patients were enrolled: 8 with two primary cancers (HER2-positive and HER2-negative BC or BC and non-BC), 7 with metastases inaccessible for biopsy, 4 with prior HER2-positive and -negative metastases and 1 with primary BC with equivocal HER2 status. ⁸⁹Zr-trastuzumab PET was positive in 12 patients, negative in 7 and equivocal in 1 patient. In 15/20 patients, ⁸⁹Zr-trastuzumab PET supported treatment decision. The scan altered treatment of 8 patients, increased physicians’ confidence without affecting treatment in 10, and improved physicians’ disease understanding in 18 patients. In 10/20 patients CTCs were detected; 6/10 showed HER2 expression. CTC HER2 status was not correlated to ⁸⁹Zr-trastuzumab PET result or treatment decision.

Conclusion

⁸⁹Zr-trastuzumab PET supports clinical decision making when HER2 status cannot be determined by standard work up. The impact of CTC HER2 status needs to be further explored.

Electronic supplementary material

The online version of this article (10.1007/s00259-018-4099-8) contains supplementary material, which is available to authorized users.

The Contribution of Fluorine 18F-FDG PET/CT to Lung Cancer Diagnosis, Staging and Treatment Planning

Objective:

Lung cancer is the most common cause of cancer-related death throughout the world, and the correct choice of treatment based on early diagnosis and staging increases the chance of survival. The present study aims to investigate the contribution of fluorine 18-fluorodeoxyglucose-positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) to the management of lung cancer.

Methods:

In this study, 50 patients who underwent ¹⁸F-FDG PET/CT for lung cancer diagnosis and staging between February 2012 and February 2014 were included. The maximum standardized uptake value (SUV_max) of the primary lung lesion along with other findings of ¹⁸F-FDG PET/CT and the results of histopathologic and conventional examinations were evaluated retrospectively. The mean survival time of patients was determined, and the findings were compared by using statistical methods.

Results:

Histopathologic examinations revealed 51 lung cancers in 50 patients. The sensitivity, accuracy and positive predictive value of ¹⁸F-FDG PET/CT in detecting primary malignancy were 94%, 94%, 100%, respectively. Adenocarcinoma (n=23, 16.8±13.5) and squamous cell carcinoma (n=15, 17.9±5.6) did not differ significantly regarding their mean SUV_max values (p=0.2). A statistically significant positive correlation (r=0.4) was identified between tumor size and SUV_max value for 51 tumors (p=0.002). The ¹⁸F-FDG PET/CT result was true negative in nine, false positive in six, true positive in two, and false negative in four patients who underwent histopathologic evaluation of their lymph nodes. The ¹⁸F-FDG PET/CT changed treatment planning in 34% of the patients. No significant relationship was identified between SUV_max value of the tumor and patient survival in patients (p=0.118).

Conclusion:

The present study concluded that PET/CT was an efficient method in the diagnosis and staging of lung cancer since it provided useful information in addition to conventional methods. It was also observed that PET/CT scanning resulted in a change in therapeutic plans in the majority of patients. However, there was no statistically significant relationship between survival and the SUV_max of the primary mass.

The impact of FDG-PET/CT in the management of patients with vulvar and vaginal cancer

OBJECTIVES

To evaluate the changes in prognostic impression and patient management following PET/CT in patients with vulvar and vaginal carcinoma; and to compare PET/CT findings with those of conventional imaging modalities.

METHODS

We summarized prospectively and retrospectively collected data for 50 consecutive patients from our institution that enrolled in the National Oncologic PET Registry and underwent FDG-PET/CT for a suspected or known primary or recurrent vulvar/vaginal cancer.

RESULTS

54/83 (65%) studies included had a diagnosis of vulvar cancer, and the remaining 29/83 (35%), a diagnosis of vaginal cancer. Following FDG-PET/CT, the physician's prognostic impression changed in 51% of cases. A change in patient management, defined as a change to/from a non-interventional strategy (observation or additional imaging), to/from an interventional strategy (biopsy or treatment), was documented in 36% of studies. The electronic records demonstrated that 95% of the management strategies recorded in the physician questionnaires were implemented as planned. MRI and/or CT were performed within one month of the FDG-PET/CT in 20/83 (24%) and 28/83 (34%) cases, respectively. FDG-PET/CT detected nodes suspicious for metastases on 29/83 (35%) studies performed. MRI and CT detected positive nodes on 6 and 11 studies respectively. Distant metastases were identified in 10 cases imaged with FDG-PET and 5 cases that had additional conventional CT imaging. All suspicious lesions seen on CT were positively identified on PET/CT. In 4 cases, an abnormality identified on PET/CT, was not seen on diagnostic CT.

CONCLUSIONS

FDG-PET/CT may play an important role in the management of vulvar and vaginal carcinoma.

Impact of FDG-PET findings on decisions regarding patient management strategies: a multicenter trial in patients with lung cancer and other types of cancer

OBJECTIVE

To date, numerous studies have been conducted on the diagnostic capabilities of positron emission tomography using [(18)F]-fluorodeoxyglucose (FDG-PET). However, no studies designed to evaluate the influence of FDG-PET on the selection of patient management strategies within the Japanese healthcare system have been reported to date. The aim of the present study was to investigate prospectively the proportion of patients whose management strategies were modified based on FDG-PET findings (strategy modification rate).

METHODS

The strategy modification rate was calculated by comparing the patient management strategy (test and treatment plans) after FDG-PET with the strategy before FDG-PET for 560 cancer patients with nine types of cancer (lung cancer, breast cancer, colorectal cancer, head/neck cancer, brain tumor, pancreas cancer, malignant lymphoma, cancer of unknown origin, and melanoma). In addition, the details of the modifications to the patient management strategies were analyzed.

RESULTS

The strategy modification rate for patients with lung cancer was 71.6% (149 of 208 patients, 95% confidence interval 65.0-77.7%), which was higher than previously reported strategy modification rates for lung cancer before and after FDG-PET (25.6%). The strategy modification rates for patients with cancers other than lung cancer were as follows: breast, 44.4% (56/126); colorectal, 75.6% (62/82); head and neck, 65.2% (15/23); malignant lymphoma, 70.0% (35/50); pancreas, 85.0% (17/20); and cancer of unknown origin, 78.0% (32/41). The mean modification rate (major and minor modifications) of the treatment plans after FDG-PET, relative to the plans before FDG-PET, was 55.4% (range 44.0-69.2%), with major modifications pertaining to the treatment plan made in 43.3-68.2% of the patients based on the objectives of the FDG-PET examination.

CONCLUSIONS

The results from this study indicate that FDG-PET can contribute to the modification of management strategies (particularly treatment plans), especially for lung cancer patients but also for patients with other types of cancer.

[The advantage of Positron Emission Tomography combined with Computer Tomography (PET-CT) in the diagnosis of lung cancer (experience with 408 patients)]

The authors analyzed the results of PET-CT scans made with oncological indications among 408 patients. One hundred and fifty-four PET-CTs were done to characterize pulmonary foci, after which in 59 cases lung surgery was performed. The method's sensitivity in respect to malignancy was 100%, specificity was 56%. Staging of affected lymph nodes resulted in 17 mediastinoscopies and 54 thoracotomies. In the former indications PET-CT-positive lymph nodes always need cytologic/histologic verification. M-staging done with PET-CT was performed in 141 cases, mediastinal restaging of patients having received neoadjuvant chemotherapy was done in 24 cases. The latter indications we consider superfluous because of the diagnostic inaccuracy of PET-CT. In 175 cases we analyzed the frequently determining factor of the PET-CT scan in the indication of lung surgery. The authors wish to share their experience for the better use of this method and to accelerate the inclusion of PET-CT into the diagnostic protocol.

Impact of positron emission tomography/computed tomography and positron emission tomography (PET) alone on expected management of patients with cancer: initial results from the National Oncologic PET Registry

PURPOSE

Under Medicare's Coverage with Evidence Development policy, positron emission tomography (PET)/computed tomography (CT) and PET became covered services for previously noncovered cancer indications if prospective registry data were collected. The National Oncologic PET Registry (NOPR) was developed to meet these coverage requirements and to assess how PET affects care decisions.

METHODS

The NOPR collected questionnaire data from referring physicians on intended patient management before and after PET. After 1 year, the cohort included data from 22,975 studies (83.7% PET/CT) from 1,178 centers. The numbers of scans performed for diagnosis of suspected cancer (or unknown primary cancer), initial cancer staging, restaging, and suspected cancer recurrence were approximately equal. Prostatic, pancreatic and ovarian cancers represented approximately 30% of cases.

RESULTS

If PET data were not available, the most common pre-PET plan would have been other imaging. In these patients, the post-PET strategies changed to watching in 37% and treatment in 48%. In patients with planned biopsy before PET, biopsy was avoided in approximately 70%. If the pre-PET strategy was treatment, the post-PET strategy involved a major change in type in 8.7% and goal in 5.6%. When intended management was classified as either treatment or nontreatment, the post-PET plan was three-fold more likely to lead to treatment than nontreatment (28.3% v 8.2%; odds ratio = 3.4; 95% CI, 3.2 to 3.6). Overall, physicians changed their intended management in 36.5% (95% CI, 35.9 to 37.2) of cases after PET.

CONCLUSION

This large, prospective, nationally representative registry of elderly cancer patients found that physicians often change their intended management on the basis of PET scan results across the full spectrum of its potential uses.

Observer variation of 2-deoxy-2-[F-18]fluoro-D-glucose-positron emission tomography in mediastinal staging of non-small cell lung cancer as a function of experience, and its potential clinical impact

Purpose

To test the extent of variation among nuclear medicine physicians with respect to staging non-small cell lung cancer with positron emission tomography (PET).

Procedures

Two groups of nuclear medicine physicians with different levels of PET experience reviewed 30 PET scans. They were requested to identify and localize suspicious mediastinal lymph nodes (MLN) using standardized algorithms. Results were compared between the two groups, between individuals, and with expert reading.

Results

Overall we found good interobserver agreement (kappa 0.65). Experience with PET translated into a better ability to localize MLN stations (68% vs. 51%, respectively), and experienced readers appeared to be more familiar with translating PET readings into clinically useful statements.

Conclusions

Although our results suggest that clinical experience with PET increases observers’ ability to read and interpret results from PET adequately, there is room for improvement. Experience with PET does not necessarily improve the accuracy of image interpretation.

Integrated PET/CT as a first-line re-staging modality in patients with suspected recurrence of ovarian cancer

PURPOSE

The aims of this study were to compare CT with PET/CT results in patients with suspected ovarian cancer recurrence and to assess the impact of the PET/CT findings on their clinical management.

METHODS

Thirty-two consecutive patients with suspected ovarian cancer recurrence were retrospectively included in the study. Abdominal contrast-enhanced CT and PET/CT with [(18)F]FDG, in addition to conventional follow-up, were performed in all 32 patients. After the comparison between CT and PET/CT results, based on clinical reports, changes in the clinical management of patients (intermodality changes) due to PET/CT information were analysed.

RESULTS

Twenty of the 32 patients were positive at CT (62.5%) versus 29 (90.6%) at PET/CT. Intermodality changes in management, i.e. use of a different treatment modality, after PET/CT examination were indicated in 14/32 (44%) patients. In particular, before PET/CT study, the planned management was as follows: wait-and-see in 7/32 (22%), further instrumental examinations in 4/32 (12%), chemotherapy in 10/32 (31%), diagnostic surgical treatment in 6/32 (19%) and surgical treatment in the remaining 5/32 (16%). After PET/CT study, wait-and-see was indicated in 1/32 (3%), further instrumental examinations in 7/32 (22%), chemotherapy in 16/32 (50%), diagnostic surgical treatment in 2/32 (6%) and surgical treatment in the remaining 6/32 (19%).

CONCLUSION

Integrated PET/CT could detect tumour relapse in a higher percentage of patients than could CT. A change in the clinical management was observed in 44% of cases when PET/CT information was added to conventional follow-up findings.

Evaluation of pulmonary nodules: comparison of a prototype dual crystal (LSO/NAI) dual head coincidence camera and full ring positron emission tomography (PET)

PURPOSE

To determine the concordance of a prototype dual head coincidence camera (LSO-PS) and full ring PET (BGO-PET) using (18)F-fluorodeoxyglucose (FDG) in the evaluation of pulmonary nodules (PNs).

MATERIALS AND METHODS

Patients referred for evaluation of < or =3 PNs (< or =3 cm diameter) were prospectively studied on the same day with both BGO-PET and LSO-PS. Imaging was performed at 60 and 120 min after injection of 370MBq FDG, respectively. Images were independently interpreted by four observers with each observer blinded to the other modality for the same patient. Lesions were scored in terms of relative intensity versus background. Non-attenuation corrected (nonAC) BGO-PET was used as the reference test.

RESULTS

Forty-seven patients with 54 PNs (mean diameter 1.7 cm, S.D. 0.7) were included. Twelve nodules were in the < or =1.0 cm - 27 in the 1.1-2.0 cm - and 15 in the 2.1-3.0 cm range. Interobserver agreement was similar for both FDG imaging modalities. Using a sensitive assessment strategy with LSO-PS (> or = faint intensity deemed positive), there was a 97% (38/39, 95%CI 87-100%) concordance with BGO-PET and one false positive case with LSO-PS. Conservative reading (moderate or intense intensity deemed positive) resulted in a 92% (36/39, 95%CI 80-97%) concordance with BGO-PET, without false positives. The only lesion missed by LSO-PS using both assessment strategies involved a nodule 1.5 cm diameter that demonstrated moderate increased FDG uptake on BGO-PET.

CONCLUSION

Depending on the test positivity criteria, LSO-PS demonstrates a high concordance (92-97%) with nonAC BGO-PET for the characterization of pulmonary nodules.

In search of an unknown primary tumour presenting with extracervical metastases: the diagnostic performance of FDG-PET

A retrospective study was carried out to determine the performance of 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) in patients with unknown primary tumours presenting with metastases external to the neck. All patients referred to an academic PET centre (July, 1997 to December, 2000) presenting with an extracervical metastasis and no prior systemic therapy were eligible. The minimum follow-up period was 11 months. From 63 eligible cases, known metastases were FDG avid in all but one neuroendocrine process. PET scans were retrospectively classified as positive for a primary tumour (n=29), i.e. revealing at least one anatomical site suspected to be the primary tumour. This was confirmed in 16, either by histology (n=10) or radiological and clinical follow-up (n=6). There were four false positive cases. In nine patients, the primary tumour was never confirmed. Of the remaining 33 negative PET scans the primary tumour was clinically not found in 18. Follow-up and additional pathology investigations demonstrated the primary tumour in 15. A survey on clinical usefulness of PET (response rate 83%) suggested that PET positively contributed to diagnostic understanding in 29 of 52 evaluable cases. Applied late in the diagnostic trajectory, approximately four patients need to be scanned by PET in order to find one primary tumour. However, in addition to direct demonstration of unknown primaries, there appears to be a positive effect on the diagnostic work-up of these patients of a similar magnitude.

Clinical Decisions Associated With Positron Emission Tomography in a Prospective Cohort of Patients With Suspected or Known Cancer at One United States Center

Purpose

In 2001, Medicare approved reimbursement of F-18 fluorodeoxyglucose positron emission tomography (PET) for a variety of cancers. PET has been observed to be more accurate than other imaging in cancer patients, but the impact of PET on management in routine practice is uncertain.

Patients and Methods

We studied a prospective cohort having noninvestigational PET at one university center. Before and after PET, a questionnaire was administered to solicit information regarding each physician's preceding actions, intended management, and probability estimates.

Results

Seventy-one physicians provided data on 248 patients, of whom 40% had new or suspected cancer and 60% were undergoing restaging or had suspected recurrence. Lung, lymphoma, and head/neck cancers accounted for two thirds of cases. Sixteen physicians made 64% of requests. Physicians changed their intended management in 61% of patients (95% CI, 54% to 66%). For individual physicians ordering at least 10 scans, the average kappa was 0.16 (range, −0.04 to 0.36), reflecting only slight level of agreement between their before and after PET plan. PET was associated with a change in 90 (79%) of 114 patients if the pre-PET intended plan involved more testing or biopsy. In 32% of cases, physicians changed to a treatment from a nontreatment strategy. The therapeutic goal and mode changed in 22 (7%) and 21 cases (8%), respectively.

Conclusion

This study confirms that physicians often change their decision making based on PET. This impact is likely due to combined effects of PET's improved accuracy and reduced physician uncertainty. Physicians may also be overconfident in interpreting PET and use it as the final arbiter after an extensive evaluation in lieu of tissue biopsy.

Impact of FDG PET on defining the extent of disease and on the treatment of patients with recurrent or metastatic breast cancer

OBJECTIVE

Our aim was to evaluate the impact of FDG PET on defining the extent of disease and on the treatment of patients with advanced breast cancer.

MATERIALS AND METHODS

The medical records of 125 consecutive patients with recurrent or metastatic breast cancer referred for FDG PET from January 1998 through May 2002 were retrospectively reviewed. The rationale for FDG PET referral and the impact of FDG PET on subsequent treatment decisions for patients were determined by chart review. The impact of FDG PET on defining the extent of disease was determined by comparing the FDG PET interpretation at the time of the examination with findings from conventional imaging (CI) performed before FDG PET. FDG PET results were confirmed in nearly half (n = 61) of the patients by histopathology (n = 23) or follow-up imaging (n = 38; mean follow-up interval, 21.3 months).

RESULTS

Patients were referred for FDG PET for the following reasons: evaluation of disease response or viability after therapy (n = 43 [35%]), local recurrence, with intent of aggressive local treatment (n = 39 [31%]), equivocal findings on CI (n = 25 [20%]), evaluation of disease extent in patients with known metastases (n = 13 [10%]), and elevated tumor markers with unknown disease site (n = 5 [4%]). Compared with CI findings, the extent of disease increased in 54 (43%), did not change in 41 (33%), and decreased in 30 (24%) of 125 patients using FDG PET. Results of FDG PET altered the therapeutic plan in 40 (32%), directly helped to support the therapeutic plan in 34 (27%), and did not change the plan devised before FDG PET in 51 (41%) of 125 patients. FDG PET altered therapy most frequently in the patients suspected of having locoregional recurrence and in those being evaluated for treatment response versus other referral categories (p = 0.04). For patients with confirmation of FDG PET findings, the sensitivity, specificity, and accuracy of FDG PET were 94%, 91%, and 92%, respectively.

CONCLUSION

FDG PET contributes significantly to defining the extent of disease and deciding on treatment of patients with advanced breast cancer.

The performance of( 18)F-fluorodeoxyglucose positron emission tomography in small solitary pulmonary nodules

Solitary pulmonary nodule (SPN, intraparenchymal lung mass <3 cm) is often a diagnostic challenge. This study was performed to evaluate the diagnostic accuracy of( 18)F-fluorodeoxyglucose positron emission tomography (FDG PET) in radiologically indeterminate SPN < or =10 mm on spiral CT. Between August 1997 and March 2001, we identified all patients with radiologically indeterminate SPNs < or =10 mm who were referred for FDG PET imaging at the VU University Medical Centre. All PET scans were retrospectively reviewed by an experienced nuclear medicine physician. PET was considered positive in cases with at least moderately enhanced focal uptake, and otherwise as negative. Lesions were considered benign on the basis of histology, no growth during 1.5 years or disappearance within at least 6 months. Thirty-five patients with 36 SPNs < or =10 mm in diameter at clinical presentation were identified (one patient had two metachronous lesions). In 13 of 14 malignant nodules and in two of 22 benign nodules, diagnosis was confirmed by histology. Prevalence of malignancy was 39%. PET imaging correctly identified 30 of 36 small lesions. One lesion proved to be false negative on PET (CT: 10 mm), and in five lesions, PET scans proved to be false positive. Specificity was 77% (17/22; 95% CI: 0.55-0.92), sensitivity 93% (13/14; 95% CI: 0.66-1.0), positive predictive value 72% (13/18; 95% CI: 0.46-0.90) and negative predictive value 94% (17/18; 95% CI: 0.73-1.0). This retrospective study suggests that FDG PET imaging could be a useful tool in differentiating benign from malignant SPNs < or =10 mm in diameter at clinical presentation. Such results may help in the design of larger prospective trials with structured clinical work-up.

An evaluation of pulmonary atelectasis and its re-expansion

RATIONALE AND OBJECTIVES

Atelectasis, the collapse of small airways, is a significant clinical problem. We use hyperpolarized (HP) 3He magnetic resonance imaging (MRI), or HP 3He MRI, to describe atelectasis in the normal Yorkshire pig, the pig with atelectasis, and the pig with re-expansion of atelectasis. We compare HP 3He MRI findings with depictions of atelectasis by proton MRI.

MATERIALS AND METHODS

During end-expiration in the anesthetized and paralyzed Yorkshire pig (n = 6), HP 3He gas produced by the optical pumping spin-exchange method, was delivered via an endotracheal tube. For two separate groups, atelectasis was either induced by Fogarty-catheter occlusion balloon inflation (n = 3), or lateral chest wall administration of sodium hydroxide (NaOH) (n = 3). MRI was performed at time zero, at 5, 9, 13, 15, and 19 minutes after atelectasis production, 30 minutes after balloon deflation, and 10 and 30 minutes after recruitment of atelectatic areas with increased tidal volumes and added positive end-expiratory pressure. High-resolution, cross-sectional MR images were procured, and comparison was made with the traditional proton MRI.

RESULTS

Atelectatic areas by HP 3He MRI were easily distinguishable in both subject groups, and correlated with those located by proton MR. HP 3He MR images showed absence of ventilation, whereas proton MR images depicted dense, white areas. Re-expansion of atelectasis was well delineated by HP 3He MRI.

CONCLUSION

HP 3He MRI may overcome many of the shortcomings of other well-established radiographic methods. HP 3He MRI is a novel, informative method for describing atelectasis and its re-expansion.