Coxiella burnetii Femoro-Popliteal Bypass Infection: A Case Report

Cardiovascular infections are the most severe and potentially lethal among the persistent focalized Coxiella burnetii infections. While aortic infections on aneurysms or prostheses are well-known, with specific complications (risk of fatal rupture), new non-aortic vascular infections are increasingly being described thanks to the emerging use of 18-fluorodeoxyglucose positron emission tomography (18F-FDG PET-scan). Here, we describe an infection of a femoro-popliteal bypass that would not have been diagnosed without the use of PET-scan. It is well-known that vascular prosthetic material is a site favorable for bacterial persistence, but the description of unusual anatomical sites, outside the heart or aorta, should raise the clinicians' awareness and generalize the indications for PET-scan, with careful inclusion of the upper and lower limbs (not included in PET-scan for cancer), particularly in the presence of vascular prostheses. Future studies will be needed to precisely determine their optimal management.

Neural correlates and effect of jealousy on cognitive flexibility in the female titi monkey (Plecturocebus cupreus)

Jealousy is a social emotion that manifests as behavioral reactions from an individual toward a threat to a valuable relationship. Monogamous species exhibit jealousy-type behaviors as an adaptive response to preserve the relationship. Jealousy is also a complex, negatively-valenced emotion which may include fear of loss, anxiety, suspiciousness, and anger. Negative emotion may impair cognitive processes such as cognitive flexibility, an ability important for coping with new situations. However, little is known about how complex social emotions influence cognitive flexibility. To understand the interaction between jealousy and cognitive flexibility, we examined the neural, physiological, and behavioral factors involved in jealousy and cognitive flexibility in female titi monkeys. We presented subjects with a jealousy provoking scenario, followed by a reversal learning task and a PET scan with a glucose-analog radiotracer. We found that female titi monkeys reacted to a jealousy provoking scenario with increased locomotor behavior and higher glucose uptake in the cerebellum; however, hormone measures and were not affected. As only two females demonstrated cognitive flexibility, the effects of jealousy were difficult to interpret. Locomotion behavior was also negatively correlated with glucose uptake in brain areas linked with motivation, sociality, and cognitive flexibility. Surprisingly, glucose uptake in the orbitofrontal cortex (OFC) was significantly decreased during jealousy scenarios, while uptake in the anterior cingulate cortex (ACC) was decreased during reversal tasks. Our findings suggest that the presence of an intruder produces less visible behavioral reactions in female titis than in males, while still reducing activity in the OFC.

Focal 18 F-FDG uptake predicts progression of pre-invasive squamous bronchial lesions to invasive cancers

INTRODUCTION

Pre-invasive squamous lesions of the central airways can progress into invasive lung cancers. Identifying these high-risk patients could enable detection of invasive lung cancers at an early stage. In this study, we investigated the value of ¹⁸ F-fluorodeoxyglucose (¹⁸ F-FDG) positron emission tomography (PET) scans in predicting progression in patients with pre-invasive squamous endobronchial lesions.

METHODS

In this retrospective study, patients with pre-invasive endobronchial lesions, who underwent an ¹⁸ F-FDG PET scan at the VU University Medical Center Amsterdam, between January 2000 and December 2016, were included. Autofluorescence bronchoscopy (AFB) was used for tissue sampling and was repeated every 3 months. The minimum and median follow-up was 3 and 46.5 months. Study endpoints were the occurrence of biopsy proven invasive carcinoma, time-to-progression and overall survival (OS).

RESULTS

A total number of 40 of 225 patients met the inclusion criteria of which 17 (42.5%) patients had a positive baseline ¹⁸ F-FDG PET scan. A total of 13 of 17 (76.5%) developed invasive lung carcinoma during follow-up, with a median time to progression of 5.0 months (range, 3.0-25.0). In 23 (57.5%) patients with a negative ¹⁸ F-FDG PET scan at baseline, 6 (26%) developed lung cancer, with a median time to progression of 34.0 months (range, 14.0-42.0 months, p < 0.002). With a median OS of 56.0 months (range, 9.0-60.0 months) versus 49.0 months (range, 6.0-60.0 months) (p = 0.876) for the ¹⁸ F-FDG PET positive and negative groups, respectively.

CONCLUSIONS

Patients with pre-invasive endobronchial squamous lesions and a positive baseline ¹⁸ F-FDG PET scan were at high-risk for developing lung carcinoma, highlighting that this patient group requires early radical treatment.

MPNST without muscle weakness at presentation: an analysis of an underappreciated combination

INTRODUCTION

Malignant peripheral nerve sheath tumors (MPNSTs) of major motor nerves typically present with muscle weakness and pain. We aim to analyze and characterize patients with MPNST at major motor nerves but without muscle weakness at initial presentation.

METHODS

A retrospective search involving MPNSTs in a major nerve evaluated and/or treated at our institution from 1994 to 2019 was performed. Patients with no muscle weakness and available MRI were analyzed. Clinical materials, MR images and PET scans were reviewed for features of malignancy. This group of patients was compared to patients who presented with MPNSTs and muscle weakness.

RESULTS

Twenty-six patients were included in the no muscle weakness group. Of them, twenty-one (81%) patients had a positive family history for malignancy. Only 16 (62%) MR images were highly suspicious for malignancy. All 7 available PET-scans were highly suspicious for malignancy. Patients who presented with muscle weakness (n = 36), were more likely to have paresthesias and a history of NF-1 or radiation to the MPNST location (p-value < 0.05).

CONCLUSION

MPNSTs of major motor nerves without muscle weakness represent an underappreciated subset of cases which has potential treatment and outcome implications. These patients presented with fewer symptoms and had fewer risk factors than patients with muscle weakness. PET-scans should be considered as an extra method of trying to anticipate the diagnosis of an MPNST.

Diagnostic Approaches for Large Vessel Vasculitides

The large vessel vasculitides comprise giant cell arteritis (GCA), Takayasu arteritis (TAK), and chronic periaortitis. The diagnostic approach to these conditions involves the correct use and interpretation of clinical criteria, imaging techniques, and, in case of GCA, temporal artery biopsy. Ultrasound, magnetic resonance imaging (MRI), and computed tomography (CT) reveal a homogeneous, concentric, thickening of the arterial wall. MRI and CT may also reveal aneurysms and stenoses. 18F-Fluorodeoxyglucose (FDG)-PET shows increased FDG uptake of inflamed artery walls delineating increased metabolic activity. Ultrasound, FDG-PET, and MRI are the recommended imaging techniques in GCA and TAK. In patients with a high suspicion of GCA who present with visual disturbances, initiation of high-dose intravenous corticosteroids should not be delayed by imaging. Extracranial large vessel vasculitis may be confirmed by all three modalities, particularly by FDG-PET in case of atypical clinical pictures. In this article, we review the role of the GCA and TAK ACR classification criteria, temporal artery biopsy, conventional angiography, ultrasound, MRI, magnetic resonance angiography (MRA), CT angiography (CTA), and FDG-PET in the diagnostic approach of large vessel vasculitis.

Sub-clinical abnormalities detected by PET/MRI in household tuberculosis contacts

Background

The understanding of early events following TB exposure is limited by traditional tests that rely on detection of an immune response to infection, which is delayed, or on imaging tests with low sensitivity for early disease. We investigated for evidence of lung abnormalities in heavily exposed TB contacts using PET/MRI.

Methods

30 household contacts of 20 index patients underwent clinical assessment, IGRA testing, chest x-ray and PET/MRI scan using 18-F-FDG. MRI images were examined by a radiology/nuclear medicine dual-qualified physician using a standardised report form, while PET/MRI images were examined independently by another radiology/nuclear medicine dual-qualified physician using a similar form. Standardised uptake value (SUV) was quantified for each abnormal lesion.

Results

IGRA was positive in 40%. PET/MRI scan was abnormal in 30%, predominantly FDG uptake in hilar or mediastinal lymph nodes and lung apices. We did not identify any relationship between PET/MRI findings and degree of exposure or IGRA status.

Conclusion

PET-based imaging may provide important insights into the natural history following exposure to TB that may not be available from traditional tests of TB immune response or imaging. The clinical significance of the abnormalities is uncertain and merits further investigation in longitudinal studies.

Isolated delayed metastasis to the talus from Ewing's sarcoma

Bone metastasis to the hands and feet, known as acrometastasis, is a very rare finding and tends to be associated with extensive metastasis. We herein report the case of a 14-year-old girl known to have a history of successfully treated Ewing's sarcoma arising from the ribs, who presented with a pathologically proven isolated metastatic lesion to the talus 7 years after achieving clinical and radiologic remission. We describe the imaging findings on MRI, CT scan and PET-CT. To our knowledge, talar metastasis from Ewing's sarcoma has been previously reported only twice in the English literature. Noteworthy is the fact that one of the previously reported lesions was considered a skip metastasis, and the other was under-described in terms of primary and secondary tumor location and time to metastasis. In addition, the overall imaging findings were rather suggestive of a benign lesion, particularly on CT scan.

Cytolytic virus activation therapy and treatment monitoring for Epstein-Barr virus associated nasopharyngeal carcinoma in a mouse tumor model

Undifferentiated nasopharyngeal carcinoma (NPC) is 100% associated with Epstein‐Barr virus (EBV). Expression of viral proteins in the tumor cells is highly restricted. EBV reactivation by CytoLytic Virus Activation (CLVA) therapy triggers de novo expression of early viral kinases (PK and TK) and uses antiviral treatment to kill activated cells. The mechanism of tumor elimination by CLVA was analyzed in NPC mouse model using C666.1 cells. Valproic acid (VPA) was combined with gemcitabine (GCb) to stimulate EBV reactivation, followed by antiviral treatment with ganciclovir (GCV). A single cycle of CLVA treatment resulted in specific tumor cell killing as indicated by reduced tumor volume, loss of EBV‐positive cells in situ, and paralleled by decreased EBV DNA levels in circulation, which was more pronounced than treatment with GCb alone. In vivo reactivation was confirmed by presence of lytic gene transcripts and proteins in tumors 6 days after GCb/VPA treatment. Virus reactivation was visualized by [¹²⁴I]‐FIAU accumulation in tumors using PET‐scan. This studied showed that CLVA therapy is a potent EBV‐specific targeting approach for killing tumor cells. The [¹²⁴I]‐FIAU appears valuable as PET tracer for studies on CLVA drug dosage and kinetics in vivo, and may find clinical application in treatment monitoring.

Aluminum adjuvants of vaccines injected into the muscle: Normal fate, pathology and associated disease

Aluminum oxyhydroxide (Alhydrogel(®)) is a nano-crystalline compound forming aggregates that has been introduced in vaccine for its immunologic adjuvant effect in 1926. It is the most commonly used adjuvant in human and veterinary vaccines but mechanisms by which it stimulates immune responses remain ill-defined. Although generally well tolerated on the short term, it has been suspected to occasionally cause delayed neurologic problems in susceptible individuals. In particular, the long-term persistence of aluminic granuloma also termed macrophagic myofasciitis is associated with chronic arthromyalgias and fatigue and cognitive dysfunction. Safety concerns largely depend on the long biopersistence time inherent to this adjuvant, which may be related to its quick withdrawal from the interstitial fluid by avid cellular uptake; and the capacity of adjuvant particles to migrate and slowly accumulate in lymphoid organs and the brain, a phenomenon documented in animal models and resulting from MCP1/CCL2-dependant translocation of adjuvant-loaded monocyte-lineage cells (Trojan horse phenomenon). These novel insights strongly suggest that serious re-evaluation of long-term aluminum adjuvant phamacokinetics and safety should be carried out.

Differential FDG-PET Uptake Patterns in Uninfected and Infected Central Prosthetic Vascular Grafts

OBJECTIVE

(18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) scanning has been suggested as a means to detect vascular graft infections. However, little is known about the typical FDG uptake patterns associated with synthetic vascular graft implantation. The aim of the present study was to compare uninfected and infected central vascular grafts in terms of various parameters used to interpret PET images.

METHODS

From 2007 through 2013, patients in whom a FDG-PET scan was performed for any indication after open or endovascular central arterial prosthetic reconstruction were identified. Graft infection was defined as the presence of clinical or biochemical signs of graft infection with positive cultures or based on a combination of clinical, biochemical, and imaging parameters (other than PET scan data). All other grafts were deemed uninfected. PET images were analyzed using maximum systemic uptake value (SUVmax), tissue to background ratio (TBR), visual grading scale (VGS), and focality of FDG uptake (focal or homogenous).

RESULTS

Twenty-seven uninfected and 32 infected grafts were identified. Median SUVmax was 3.3 (interquartile range [IQR] 2.0-4.2) for the uninfected grafts and 5.7 for the infected grafts (IQR 2.2-7.8). Mean TBR was 2.0 (IQR 1.4-2.5) and 3.2 (IQR 1.5-3.5), respectively. On VGS, 44% of the uninfected and 72% of the infected grafts were judged as a high probability for infection. Homogenous FDG uptake was noted in 74% of the uninfected and 31% of the infected grafts. Uptake patterns of uninfected and infected grafts showed a large overlap for all parameters.

CONCLUSION

The patterns of FDG uptake for uninfected vascular grafts largely overlap with those of infected vascular grafts. This questions the value of these individual FDG-PET-CT parameters in identifying infected grafts.