Diagnostic relevance of 18F-FDG PET/CT in newly diagnosed patients with monoclonal gammopathy of undetermined significance (MGUS): Single-center experience

Monoclonal gammopathy of undetermined significance (MGUS) is a known precursor of more serious cancers, such as multiple myeloma (MM), Waldenström macroglobulinemia (MW) and other lymphoproliferative disorders. Using 18F-FDG PET/CT, we aimed to evaluate its benefit in early detection of various accompanying disorders and illnesses in MGUS patients. We prospectively analyzed the diagnostic relevance of 18F-FDG PET/CT in 390 newly diagnosed MGUS patients. On 18F-FDG PET/CT scans, the presence of focal or diffuse areas of detectable increased tracer uptake was recorded in 37 (9.5%) MGUS patients. The most frequent pathology was lymphadenopathy (3.8%), followed by thyroid diseases (2.1%), rheumatic diseases (1.8%), and other solid malignancies (1.5%). These results have major implications for confirmed associations of MGUS with numerous malignant and non-malignant disorders. We believe that 18F-FDG PET/CT imaging in newly diagnosed MGUS patients may be useful in early detection of other serious pathologies, not only in predicting progression of MGUS to active MM, and should be strongly recommended if available.

In silico study of pseudoprogression in glioblastoma: collaboration of radiologists and radiation oncologists in the estimation of extent of high dose RT region

BACKGROUND AND AIM

Oncologists play a vital role in the interpretation of radiographic results in glioblastoma patients. Molecular pathology and information on radiation treatment protocols among others are all important for accurate interpretation of radiology images. One important issue that may arise in interpreting such images is the phenomenon of tumor "pseudoprogression"; oncologists need to be able to distinguish this effect from true disease progression.Exact knowledge about the location of high-dose radiotherapy region is needed for valid determination of pseudoprogression according to RANO (Response Assessment in Neuro-Oncology) criteria in neurooncology. The aim of the present study was to evaluate the radiologists' understanding of a radiotherapy high-dose region in routine clinical practice since radiation oncologists do not always report 3-dimensional isodoses when ordering follow up imaging.

METHODS

Eight glioblastoma patients who underwent postresection radiotherapy were included in this study. Four radiologists worked with their pre-radiotherapy planning MR, however, they were blinded to RT target volumes which were defined by radiation oncologists according to current guidelines. The aim was to draw target volume for high dose RT fields (that is the region, where they would consider that there may be a pseudoprogression in future MRI scans). Many different indices describing structure differences were analyzed in comparison with original per-protocol RT target volumes.

RESULTS

The median volume for RT high dose field was 277 ccm (range 218 to 401 ccm) as defined per protocol by radiation oncologist and 87 ccm (range 32-338) as defined by radiologists (median difference of paired difference 31%, range 15-112%). The Median Dice index of similarity was 0.46 (range 0.14 - 0.78), the median Hausdorff distance 25 mm.

CONCLUSION

Continuing effort to improve education on specific procedures in RT and in radiology as well as automatic tools for exporting RT targets is needed in order to increase specificity and sensitivity in response evaluation.

PET/CT imaging in polymyalgia rheumatica: praepubic 18F-FDG uptake correlates with pectineus and adductor longus muscles enthesitis and with tenosynovitis

Background

The role of ¹⁸F-fluorodeoxyglucose positron emission computed tomography (¹⁸F-FDG PET/CT) is increasing in the diagnosis of polymyalgia rheumatica (PMR), one of the most common inflammatory rheumatic diseases. In addition to other locations, increased ¹⁸F-FDG accumulation has been detected in the praepubic region in some patients. However, a deeper description and pathophysiological explanation of this increased praepubic accumulation has been lacking. The aim of the presented study is to confirm a decrease in praepubic ¹⁸F-FDG accumulation in response to therapy and to describe potential correlations to other ¹⁸F-FDG PET/CT scan characteristics during the course of disease. As a secondary objective, we describe the pathological aspects of the observed praepubic ¹⁸F-FDG uptake.

Patients and methods

A retrospective review of patients with newly suspected PMR undergoing baseline and follow up ¹⁸F-FDG PET/CT between February 2010 and March 2016 is given. Those with a visually detected presence of praepubic ¹⁸F-FDG accumulation were further analysed. The uptake was assessed visually and also semi-quantitatively in the defined region of interest by calculation of target-to-liver ratios. Other regions typical for PMR were systematically described as well (shoulders, hips, sternoclavicular joints, ischiogluteal bursae, spinous interspaces).

Results

Twenty-three out of 89 screened patients (26%) presented with initial praepubic ¹⁸F-FDG PET/CT positivity, 15 of whom also underwent follow up ¹⁸F-FDG PET/CT examination. Five out of 15 patients presented with increased ¹⁸F-FDG accumulation in large arteries as a sign of giant cell arteritis. During follow up examination, decrease in ¹⁸F-FDG accumulation caused by therapeutic intervention was observed in all evaluated locations in all analysed patients and no new positivity was indicated, including periarticular, extraarticular tissues or target large vessels. Praepubical accumulation of ¹⁸F-FDG was diminished in all patients (15/15, 100%) after treatment with steroids.

Conclusions

Increased praepubic ¹⁸F-FDG uptake in patients with PMR is relatively common and this region should be systematically evaluated during differential diagnosis of rheumatic and malignant disease. Praepubic inflammation is probably related to enthesitis and tenosynovitis at the origin of pectineus and adductor longus muscles ventrally from the pubis.

Salvage lenalidomide in four rare oncological diseases

In rare disorders, there are often no standard therapy recommendations. Patients with refractory disease may require novel experimental approaches. Applied as second- up to fourth-line treatment, lenalidomide (10-25 mg perorally on days 1-21 in a 28-day cycle) was used in our cohort of four adult patients with aggressive, multisystem and relapsing diseases. Complete and long-lasting remissions (more than 1 year, no maintenance therapy) were achieved in patients with Langerhans cell histiocytosis (11 cycles, combination with dexamethasone and etoposide, consolidated by allogeneic blood stem cell transplant) and plasma-cell Castleman disease (15 cycles, monotherapy). Mixed response with complete disappearance of brain infiltrates was reached in Erdheim-Chester disease (6 cycles, monotherapy) and gastrointestinal bleeding was well controlled in multiple angiomatosis (9 cycles, combination with thalidomide). For disease activity evaluation each patient underwent fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography scan imaging, which was complemented by clinical and laboratory investigations.

Salvage lenalidomide in four rare oncological diseases

In rare disorders, there are often no standard therapy recommendations. Patients with refractory disease may require novel experimental approaches. Applied as second- up to fourth-line treatment, lenalidomide (10–25 mg perorally on days 1–21 in a 28-day cycle) was used in our cohort of four adult patients with aggressive, multisystem and relapsing diseases. Complete and long-lasting remissions (more than 1 year, no maintenance therapy) were achieved in patients with Langerhans cell histiocytosis (11 cycles, combination with dexamethasone and etoposide, consolidated by allogeneic blood stem cell transplant) and plasma-cell Castleman disease (15 cycles, monotherapy). Mixed response with complete disappearance of brain infiltrates was reached in Erdheim-Chester disease (6 cycles, monotherapy) and gastrointestinal bleeding was well controlled in multiple angiomatosis (9 cycles, combination with thalidomide). For disease activity evaluation each patient underwent fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography scan imaging, which was complemented by clinical and laboratory investigations.