Diagnostic performance of CT, PET, side-by-side, and fused image interpretations for restaging of non-Hodgkin lymphoma

Utility of minimally invasive thoracoscopy for assessment of residual mediastinal lymphoma

BACKGROUND

Patients with primary mediastinal lymphomas frequently present with a residual mass after completion of first-line therapy. Although a positron emission tomography scan is usually recommended, it fails to distinguish between persistent lymphoma and inflammation. Although percutaneous biopsy may have a high diagnostic yield for the initial diagnosis of mediastinal lymphomas, this biopsy has poor accuracy for detecting persistent disease in a residual mass given the heterogeneity of these residual masses. Because persistent disease has important therapeutic implications, we evaluated the role of operative biopsy in detecting lymphoma in the residual mass.

METHODS

Between 2009 and 2015, consecutive patients (n = 77) undergoing tissue biopsy for initial diagnosis as well as for a positron emission tomography-positive residual mass were included. Tissue biopsy for a residual mass was repeated until frozen section was diagnostic or at least the mass on the ipsilateral hemi-mediastinum was resected.

RESULTS

Of the initial 77 patients, 34 underwent operative restaging for a residual mass after chemotherapy, while 43 had a complete response. In these 34 patients, operative biopsy revealed the presence of lymphoma in 53%, predominantly Hodgkin's disease and diffuse large B-cell lymphoma. There was no significant difference in tumor volume (51% versus 39%) and a decrease in the positron emission tomography-standardized uptake value_max (68% vs 60%) in patients with or those without persistent lymphoma. There were no surgical complications and the duration of stay for all patients undergoing thoracoscopy was <24 hours. Residual lymphoma was treated with second-line therapy guided by the pathologic analysis.

CONCLUSION

A large proportion of patients with residual positron emission tomography-avidity after first-line chemotherapy of mediastinal lymphomas have residual disease that can be detected safely using minimally invasive thoracoscopy.

FDG-PET Scan: a new Paradigm for Follicular Lymphoma Management

In the present review, the reader will be led to the most relevant observations that prompted oncologists and haematologist to consider FDG-PET/CT as a new paradigm for FL management in clinical practice. The role of functional imaging in lymphoma staging, restaging, prognostication, and metabolic tumour volume computing will be reviewed in detail. Moreover, a special focus will be addressed to technical and practical aspects of PET scan reporting, which have been set during the last decade to ensure the reproducibility of the therapeutic results. Finally, the predictive role of PET/CT on long-term treatment outcome will be compared with another well-known prognosticator as minimal residual disease (MRD) detection by Immunoglobulin gene rearrangement assessment.

Low-Dose PET/CT and Full-Dose Contrast-Enhanced CT at the Initial Staging of Localized Diffuse Large B-Cell Lymphomas

Computed tomography (CT) has been used as the reference imaging technique for the initial staging of diffuse large B-cell lymphoma until recent days, when the introduction of positron emission tomography (PET)/CT imaging as a hybrid technique has become of routine use. However, the performance of both examinations is still common. The aim of this work was to compare the findings between low-dose 2-deoxy-2-(¹⁸F)fluoro-d-glucose (¹⁸F-FDG) PET/CT and full-dose contrast-enhanced CT (ceCT) in 28 patients with localized diffuse large B-cell lymphoma according to PET/CT findings, in order to avoid the performance of ceCT. For each technique, a comparison in the number of nodal and extranodal involved regions was performed. PET/CT showed more lesions than ceCT in both nodal (41 vs. 36) and extranodal localizations (16 vs. 15). Disease staging according to both techniques was concordant in 22 patients (79%) and discordant in 6 patients (21%), changing treatment management in 3 patients (11%). PET/CT determined a better staging and therapeutic approach, making the performance of an additional ceCT unnecessary.

Impact of FDG-PET/CT in the management of lymphoma

Since the introduction of (67)Gallium-citrate 30 years ago, nuclear medicine has played an important role in the evaluation of malignant lymphoma. During that time, several radiotracers were evaluated as potential alternatives for the diagnosis of lymphoma, but the introduction of (18)F-fluorodeoxyglucose PET (FDG-PET) marked a major turning point. FDG-PET took over most of the role of gallium, and is now an essential tool in the diagnosis of lymphoma. FDG-PET is increasingly being used for assessment of the tumor staging prior to treatment, for evaluating the response to treatment, and for monitoring the early reactions to therapy to predict the final outcome. FDG-PET has been shown to have more accurate diagnostic capability than conventional CT and MRI for distinguishing the tumor necrosis and residual masses frequently seen after therapy in lymphoma patients without any clinical and biochemical manifestation. Malignant lymphoma is the first disease for which FDG-PET was adopted as a tool for response assessment in the international standard criteria. However, lymphoma does not always display a clear high uptake, and there are some pitfalls in assessing the response to therapy. This review will highlight the most important applications of FDG-PET in lymphoma, focusing on the advantages and pitfalls of this imaging, and past and ongoing efforts to standardize the use of FDG-PET, particularly in response to assessment and therapy monitoring.

Detecting the recurrence of gastric cancer after curative resection: comparison of FDG PET/CT and contrast-enhanced abdominal CT

The purpose of this study was to evaluate the value of fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) for detecting the recurrence of gastric cancer. We performed a retrospective review of 139 consecutive patients who underwent PET/CT and contrast-enhanced abdominal CT (CECT) for surveillance of gastric cancer after curative resection. Recurrence of gastric cancer was validated by histopathologic examination for local recurrence or serial imaging study follow-up with at least 1 yr interval for recurrence of distant metastasis form. Twenty-eight patients (20.1%) were confirmed as recurrence. On the patient based analysis, there was no statistically significant difference in the sensitivity, specificity and accuracy of PET/CT (53.6%, 84.7%, and 78.4%, respectively) and those of CECT (64.3%, 86.5%, and 82.0%, respectively) for detecting tumor recurrence except in detection of peritoneal carcinomatosis. Among 36 recurrent lesions, 8 lesions (22.2%) were detected only on PET/CT, and 10 lesions (27.8%) only on CECT. PET/CT had detected secondary malignancy in 8 patients. PET/CT is as accurate as CECT in detection of gastric cancer recurrence after curative resection, excepting detection of peritoneal carcinomatosis. Moreover, additional PET/CT on CECT could improve detection rate of tumor recurrence and provide other critical information such as unexpected secondary malignancy.

Is contrast material needed after treatment of malignant lymphoma in positron emission tomography/computed tomography?

PURPOSE

Positron emission tomography (PET)/computed tomography (CT) with (18)F-fluorodeoxyglucose is widely used for post-therapeutic surveillance of malignant lymphoma. Debate still exists as to whether intravenous contrast media during the CT stage of a PET/CT scan should be used. The purpose of this study was to investigate the clinical value of contrast agent in PET/CT in patients with lymphoma following treatment.

PATIENTS AND METHODS

One hundred and twenty-two consecutive patients with malignant lymphoma underwent 146 PET/CT scans to monitor therapeutic response (n = 57) or surveillance during follow-up (n = 89). All patients had a conventional PET/CT scan with low-dose CT without contrast (ldCT), and then a full-dose CT scan with contrast (ceCT). Two datasets were interpreted separately and prevalence of discrepant results between the two methods was evaluated. In addition, differences of diagnostic performance were investigated for restaging.

RESULTS

Both PET + ldCT and PET + ceCT were positive in 22 cases and negative in 35 cases when monitoring response to therapy. There were no cases in which these techniques demonstrated inconsistent findings. For restaging, the patient-based sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of PET + ldCT were 70, 91, 76, 87, and 84%, respectively, and those of PET + ceCT were 74, 92, 81, 89, and 87%, respectively. Discrepant results between the two methods occurred in only 2 of 89 cases (2%).

CONCLUSION

PET/ceCT yielded more accurate findings than PET/ldCT in a limited number of cases. PET/ldCT may, therefore, be sufficient for routine PET/CT scanning for post-therapeutic assessment or restaging of lymphoma patients.

Non-Hodgkin's lymphoma presenting as a primary bladder tumor: a case report

Introduction

Primary lymphoma of the bladder represents 0.2% of all bladder malignancies. Secondary involvement of the bladder by malignant lymphoma occurs in 10% to 50% of cases. Most lymphomas of the bladder are non-Hodgkin's lymphomas of the B-cell type, with preponderance among women. The impact of positron emission tomography (PET) on tumor staging has recently become very important due to its use in the study of diagnosis extension and individual therapy design.

Case presentation

We report the case of a 79-year-old Caucasian man with intermittent haematuria as the presenting symptom of non-Hodgkin's lymphoma of the bladder. He was first diagnosed with primary lymphoma of the bladder using the current staging method, but a positron emission tomography study subsequently revealed that he instead had a secondary involvement of the bladder.

Conclusion

The staging of non-Hodgkin's lymphomas, which is useful in order to plan accurate therapy, has been changing since the introduction of positron emission tomography scanning. Primary lymphomas of the bladder, although very rare, may be even more uncommon when this imaging technique is used to assess the extension of the disease. Although the interpretation of this technique has some limitations that should be taken into account, the extensive use of positron emission tomography should nonetheless help improve the diagnosis of this disease.

Clinical value of whole-body FDG-PET for recurrent gastric cancer: a multicenter study

OBJECTIVE

The purpose of this multicenter study was to evaluate the clinical usefulness of positron emission tomography (PET) using (18)F-fluorodeoxyglucose (FDG) for suspected recurrent gastric cancer.

METHODS

We performed a retrospective review of 92 consecutive patients who underwent PET [either integrated PET/computed tomography (CT) or manual fusion of dedicated PET and CT] scans for post-treatment surveillance of gastric cancer between June 2006 and December 2007. Of these patients, 46 patients were suspected of recurrence by other imaging modalities (Group A), 19 patients were suspected of recurrence by tumor markers without definite findings (Group B) and the remaining 27 patients underwent a PET scan without evidence of recurrence (Group C). The diagnostic performance and prevalence of the clinical impact of FDG-PET were analyzed.

RESULTS

Recurrence of gastric cancer was confirmed in 31 patients (67%) in Group A, in 11 patients (58%) in Group B and in 2 patients (7%) in Group C. In addition, colon cancer (n = 3), lung cancer (n = 1) and pulmonary carcinoid (n = 1) were identified in five patients (5%). In patient-basis, the sensitivity, specificity and diagnostic accuracy of PET for recurrence were 81%, 87% and 83%, respectively, in Group A, 73%, 88% and 79%, respectively, in Group B and 50%, 88% and 85%, respectively, in Group C. Therapeutic management was influenced by PET results in 22 patients (48%) in Group A, in 8 patients (42%) in Group B and in 2 patients (7%) in Group C, including cases in which PET was helpful for detecting second primary cancer.

CONCLUSIONS

PET with FDG yielded useful information in patients with suspected recurrent gastric cancer, especially when recurrence was suspected in the clinical setting.

The impact of fluorodeoxyglucose-positron emission tomography in primary staging and patient management in lymphoma patients

Fully diagnostic positron emission tomography (PET)/CT scans acquired during oral and intravenous contrast can be provided to patients and referring physicians in a single imaging session. Although FDG uptake varies, most low-grade lymphomas exhibit sufficient FDG avidity to also be staged reliably with FDG PET/CT. PET/CT imaging is more accurate for lymphoma staging than PET or CT alone and has substantial impact on patient management. This accurate whole-body glucose metabolic survey should serve as the baseline for subsequent treatment response evaluations. PET/CT has evolved to become the modality of choice for staging of nodal and extranodal lymphoma, for assessing therapeutic response, and for establishing patient prognosis.

FDG PET scan strategies and long-term outcomes after first-line therapy in Hodgkin's disease

BACKGROUND

The use of positron emission tomography with fluoro-deoxy-glucose (FDG PET) in Hodgkin's disease (HD) is continuing to expand worldwide, with response assessment after completion of therapy being its most widely utilized application. A positive scan has been associated with high relapse rates and disease progression.

METHODS

A decision analysis was performed to determine the long-term impact of FDG PET restaging both with and without computed tomography (CT) in terms of the 5-year progression-free survival (5yrPFS). Outcomes and utilities were based on published data. The first strategy involved CT restaging after first-line therapy, with or without subsequent FDG PET, while the second strategy used FDG PET scan alone. All positive test required histological examination. Upon histological confirmation of active lymphoma, patients were considered candidates for autologous transplantation and long-term outcomes were retrieved. The expected clinical benefit of the two strategies was calculated and depicted, along with the mean costs. One-way and two-way sensitivity analyses were performed to ensure the validity of the results.

RESULTS

CT restaging plus FDG PET when residual mass is detected, results in a 2% benefit at 5yrPFS at baseline compared to FDG PET-alone restaging and remains positive for a wide range of probabilities. This strategy reduces the average cost by euro 1863 per patient, including costs of biopsy and autologous transplantation.

CONCLUSION

A more conservative approach that includes CT restaging after first-line therapy and FDG PET scan only on residual mass, is the preferred strategy in HD. Furthermore it appears to confer the maximal diagnostic yield along with a substantial reduction in the mean cost.