[Importance of PET/CT in lymphoma diagnostics]

Minimally Invasive Diagnosis of Secondary Intracranial Lymphoma

Diffuse large B cell lymphomas (DLBCL) are an aggressive group of non-Hodgkin lymphoid malignancies which have diverse presentation and can have high mortality. Central nervous system relapse is rare but has poor survival. We present the diagnosis of primary mandibular DLBCL and a unique minimally invasive diagnosis of secondary intracranial recurrence. This case highlights the manifold radiological contributions to the diagnosis and management of lymphoma.

Diffusion-weighted MRI compared to FDG PET/CT for assessment of early treatment response in lymphoma

BACKGROUND

18F fluoro-deoxyglucose (FDG) positron emission tomography / computed tomography (PET/CT) is a well-recognized diagnostic tool used for staging and monitoring of therapy response for lymphomas. During the past decade diffusion-weighted (DW) magnetic resonance imaging (MRI) is increasingly being included in the assessment of tumor response for various cancers.

PURPOSE

To compare the change in maximum standardized uptake value (ΔSUVmax) from FDG PET/CT with the change in apparent diffusion coefficient (ΔADC) from DW MRI after initiation of the first cycle of chemotherapy in patients with Hodgkin's lymphoma (HL) and in patients with diffuse large B-cell lymphoma (DLBCL).

MATERIAL AND METHODS

Twenty-seven consecutive patients with histologically proven lymphoma and lymphomatous lymph nodes (LLN) of the neck (19 with HL, 8 with DLBCL) underwent FDG PET/CT and MRI of the neck before and after initiation of the first cycle of chemotherapy. The mean time interval from initiation of chemotherapy to imaging was 19 days and 2 days for FDG PET/CT and MRI, respectively. For each patient ΔSUVmax, ΔADC, and change in volume of the same LLN were compared.

RESULTS

There was a significant mean decrease of SUVmax by 70%, but no significant change in ADC. There was no significant reduction in LLN volume.

CONCLUSION

There was no significant correlation between ΔSUVmax and ΔADC. Thus, our data do not support that FDG PET/CT can be replaced by early DW MRI for response evaluation in lymphoma patients.

Thoracoscopic approach of the internal thoracic lymphatic chain

OBJECTIVE

Few studies to date have evaluated the videothoracoscopic approach of the internal thoracic lymphatic chain. However, the histological evaluation of lymph nodes is essential for patients with breast cancer who show lymph node uptake at scintigraphy in the preoperative period and also for patients with lymphoma who have exclusive uptake in these lymph nodes at positron emission tomography for recurrence assessment. Our goal was to evaluate the safety and the change in oncologic approach through this minimally invasive technique.

METHODS

This is a review of the prospectively collected data in a group of patients undergoing thoracoscopic biopsy of the thoracic lymphatic chain in patients with breast cancer and lymphoma carried out in our institution between September 2010 and June 2012. The analyzed variables include age, histological type, operated hemithorax, number of resected lymph nodes, neoplastic involvement of the resected lymph nodes, duration of chest tube drainage, length of hospital stay, and perioperative mortality. Complications such as subcutaneous emphysema and necessity for blood transfusion were also evaluated.

RESULTS

Thoracoscopic biopsy was successfully performed in 16 patients, of whom 14 had breast cancer and 2 had lymphoma. The surgical biopsy results changed the treatment in the two patients with lymphoma and avoided radiotherapy in the eight patients with breast cancer who did not have metastases.

CONCLUSIONS

The use of the thoracoscopic assessment of the internal thoracic lymphatic chain seems safe and resulted in therapy modification in more than half of our patients, suggesting that it is an effective technique for staging in selected breast cancer and lymphoma cases.

Enhancement characteristics of retroperitoneal lymphomatous lymph nodes

BACKGROUND

Previous studies of CT enhancement of lymphomatous lymph nodes (LLN) of the neck and the mediastinum showed that the LLN had lower enhancement values than normal lymph nodes.

PURPOSE

To elucidate the contrast medium enhancement curves of LLN in the retroperitoneum by comparing the curves of LLN with those of normal lymph nodes, to test whether differences between these curves could be of diagnostic value, and to compare the present enhancement curves of LLN of the retroperitoneum with the curves of LLN of the neck and the mediastinum from previous similar investigations.

MATERIAL AND METHODS

Twenty-eight consecutive patients with LLN of the retroperitoneum (three with Hodgkin's lymphoma [HL]) and 21 control patients with sarcomas and thus presumably normal retroperitoneal nodes underwent dynamic CT examinations. The previous, similar investigation of lymph nodes of the neck comprised 28 patients with LLN and the investigation of mediastinal lymph nodes comprised 24 patients with LLN.

RESULTS

The enhancement curves of the retroperitoneal LLN had significantly lower attenuation than those of the retroperitoneal control nodes. A combination of peak contrast value and time to peak adjusted to total body weight yielded a diagnostic accuracy which at the best showed a sensitivity of 90.5% with a specificity of 82.6%. The LLN of the retroperitoneum had higher attenuation values than corresponding nodes of the mediastinum but no significant difference was found between LLN of the retroperitoneum and LLN of the neck in previous similar investigations.

CONCLUSION

The comparison of enhancement curves of retroperitoneal LLN with retroperitoneal control nodes showed a marked similarity with and substantiates our previous findings in lymph nodes of the neck and of the mediastinum. The best diagnostic accuracy was achieved by combining the parameters peak contrast value and time to peak and adjusting these values to the body weight. Peak enhancement of the retroperitoneal LLN was higher and arrived earlier than that of the mediastinal nodes from the previous investigation.