Gadolinium-enhanced MRI of intracranial lesions. A review of indications and results

Regulatable interleukin-12 gene therapy in patients with recurrent high-grade glioma: Results of a phase 1 trial

Human interleukin-12 (hIL-12) is a cytokine with anticancer activity, but its systemic application is limited by toxic inflammatory responses. We assessed the safety and biological effects of an hIL-12 gene, transcriptionally regulated by an oral activator. A multicenter phase 1 dose-escalation trial (NCT02026271) treated 31 patients undergoing resection of recurrent high-grade glioma. Resection cavity walls were injected (day 0) with a fixed dose of the hIL-12 vector (Ad-RTS-hIL-12). The oral activator for hIL-12, veledimex (VDX), was administered preoperatively (assaying blood-brain barrier penetration) and postoperatively (measuring hIL-12 transcriptional regulation). Cohorts received 10 to 40 mg of VDX before and after Ad-RTS-hIL-12. Dose-related increases in VDX, IL-12, and interferon-γ (IFN-γ) were observed in peripheral blood, with about 40% VDX tumor penetration. Frequency and severity of adverse events, including cytokine release syndrome, correlated with VDX dose, reversing promptly upon discontinuation. VDX (20 mg) had superior drug compliance and 12.7 months median overall survival (mOS) at mean follow-up of 13.1 months. Concurrent corticosteroids negatively affected survival: In patients cumulatively receiving >20 mg versus ≤20 mg of dexamethasone (days 0 to 14), mOS was 6.4 and 16.7 months, respectively, in all patients and 6.4 and 17.8 months, respectively, in the 20-mg VDX cohort. Re-resection in five of five patients with suspected recurrence after Ad-RTS-hIL-12 revealed mostly pseudoprogression with increased tumor-infiltrating lymphocytes producing IFN-γ and programmed cell death protein 1 (PD-1). These inflammatory infiltrates support an immunological antitumor effect of hIL-12. This phase 1 trial showed acceptable tolerability of regulated hIL-12 with encouraging preliminary results.

Usefulness of 11C-methionine positron emission tomography for detecting intracranial ameloblastic carcinoma: A case report

Ameloblastic carcinoma, secondary type, is an extremely rare odontogenic malignant tumor. The present study reports the case of a 58-year-old male with ameloblastic carcinoma that extended into the intracranial space close to the internal carotid artery. Surgical excision was performed, as headaches were being caused via compression by the mass. Small remnants of the tumor remained surrounding the internal carotid artery following surgical resection. Although the remnant tissue was not detected on magnetic resonance imaging or 18F-fluorodeoxyglucose (FDG)-positron emission tomography (PET), it was clearly visualized on ¹¹C-methionine PET in the early post-operative follow-up period. No neurological deficits were exhibited during the follow-up period, and ¹¹C-methionine PET was able to detect the remnant lesion distribution in the intracranial space. The current study presents a rare case of ameloblastic carcinoma that extended into the intracranial space. In addition, several diagnostic imaging tools were compared in order to determine the most suitable imaging modality. At present, the patient is continuing a therapeutic course of radiation and evident mass reduction has been observed. However, the therapeutic effects are currently under consideration. To the best of our knowledge, this is the first study on the effectiveness of using ¹¹C-methionine PET for detecting ameloblastic carcinoma with intracranial extension.

Malignant gliomas: current perspectives in diagnosis, treatment, and early response assessment using advanced quantitative imaging methods

Malignant gliomas consist of glioblastomas, anaplastic astrocytomas, anaplastic oligodendrogliomas and anaplastic oligoastrocytomas, and some less common tumors such as anaplastic ependymomas and anaplastic gangliogliomas. Malignant gliomas have high morbidity and mortality. Even with optimal treatment, median survival is only 12–15 months for glioblastomas and 2–5 years for anaplastic gliomas. However, recent advances in imaging and quantitative analysis of image data have led to earlier diagnosis of tumors and tumor response to therapy, providing oncologists with a greater time window for therapy management. In addition, improved understanding of tumor biology, genetics, and resistance mechanisms has enhanced surgical techniques, chemotherapy methods, and radiotherapy administration. After proper diagnosis and institution of appropriate therapy, there is now a vital need for quantitative methods that can sensitively detect malignant glioma response to therapy at early follow-up times, when changes in management of nonresponders can have its greatest effect. Currently, response is largely evaluated by measuring magnetic resonance contrast and size change, but this approach does not take into account the key biologic steps that precede tumor size reduction. Molecular imaging is ideally suited to measuring early response by quantifying cellular metabolism, proliferation, and apoptosis, activities altered early in treatment. We expect that successful integration of quantitative imaging biomarker assessment into the early phase of clinical trials could provide a novel approach for testing new therapies, and importantly, for facilitating patient management, sparing patients from weeks or months of toxicity and ineffective treatment. This review will present an overview of epidemiology, molecular pathogenesis and current advances in diagnoses, and management of malignant gliomas.

Are cerebral cavernomas truly nonenhancing lesions and thereby distinguishable from arteriovenous malformations? MRI findings and histopathological correlation

PURPOSE

The aim of this study was to determine whether cerebral cavernomas are truly nonenhancing lesions on magnetic resonance imaging (MRI), whether they can be distinguished from arteriovenous malformations (AVM) on that basis and to evaluate the incidence of their association with developmental venous anomalies (DVA).

PATIENTS AND METHODS

Thirty-two patients who underwent neurosurgical operation for a cerebral vascular malformation and had a standard MRI conclusive of cerebral cavernoma were retrospectively evaluated for size of the lesions, contrast enhancement of the lesion and the coexistence of DVA. The contrast uptake of these lesions was investigated, and contrast enhancement was classified as none, moderate or marked. The incidence of an associated DVA was also investigated. The radiological findings were subsequently correlated with neurohistopathological findings.

RESULTS

No difference was found between the contrast enhancement of cavernomas and AVMs. Cross tables were calculated for contrast enhancement and size, which demonstrated no statistically significant correlation. Cross tables were calculated for contrast enhancement and histopathological diagnosis, which revealed that both entities presented variable degrees of contrast enhancement and were thereby not distinguishable from each other on the basis of contrast enhancement. We found an association of cavernoma with DVA in 30% of cases.

CONCLUSION

Neither a correlation between the absence of contrast enhancement and the histopathological diagnosis of cavernoma nor the size and contrast enhancement was found. We conclude that cavernomas present with variable degrees of contrast enhancement on MRI and, thus, are definitely not distinguishable from AVM on the basis of contrast enhanced MRI. We found an association between cavernomas and DVA in approximately one third of patients.

A new semiquantitative method for comparing brain tumor uptake of Tc-99m sestamibi and TI-201

PURPOSE

We describe a new method for measuring brain tumor uptake of TI-201 and Tc-99m sestamibi (MIBI) that permits the semiquantitative comparison of tracer uptake to yield comparable "tumor bulk" ratios. We tested this method in patients treated recently and remotely with chemotherapy to determine if this method could identify differences between these two patient groups.

METHODS

Eleven patients with high-grade astrocytoma underwent TI-201 and Tc-99m MIBI SPECT. Each patient received 5 mCi TI-201 intravenously followed by SPECT using a dual-head gamma camera. This was immediately followed by an intravenous injection of 20 mCi Tc-99m MIBI and repeated SPECT. Four patients had recent therapy (from 1 day to 6 weeks before SPECT) and seven had remote treatment (>1 year before SPECT). Regions of interest were outlined in the tumor area using a computer-automated program to include all counts above background activity. Tumor activity counts were obtained from this region of interest. The tumor region of interest was mirrored to the contralateral uninvolved cerebral hemisphere to obtain background control count activity. A hypothetical volume of the number of pixels with background count activity necessary to constitute the tumor count activity (tumor bulk) was calculated using the ratio of total tumor counts (Ct), subtracting background (Cb), and dividing by the average counts per pixel in the control region (Cab). This was multiplied by the number of pixels (P), the pixel volume (Vp), and summed over all sections (i) involved with tumor. This method yields the equation tumor bulk =

RESULTS

The mean Tc-99m MIBI to TI-201 tumor bulk ratio was 1.03 (range, 0.81 to 1.12) in four patients who had recently received chemotherapy. The mean Tc-99m MIBI to TI-201 tumor bulk ratio was 1.55 (range, 1.46 to 1.64) in seven patients who had remote therapy. The difference in the Tc-99m MIBI to TI-201 tumor bulk ratio between the two groups was significant (P = 0.0001). Patients who received recent chemotherapy had relatively lower Tc-99m MIBI uptake compared with TI-201. In remotely treated patients, uptake of the Tc-99m MIBI was greater compared with TI-201.

CONCLUSION

This method allows semiquantitative comparison of different tracer uptake values independent of tracer dose and reduces the variability in drawing a region of interest when measuring tumor uptake. Among the patients studied, those who had recent chemotherapy showed a low Tc-99m MIBI to TI-201 ratio. This method of measuring "tumor bulk" can provide a useful index of viable tumor size in evaluating early tumor response and during ongoing chemotherapy.

Childhood brain tumor: neuroimaging correlated with disease outcome

The authors explored the hypothesis that functional behavior of childhood brain tumors can be estimated by serial analysis of imaging (thallium-201 [201Tl] single-photon emission computed tomography and magnetic resonance imaging [MRI]) examinations. Seventy-five patients diagnosed on clinical or histologic grounds were monitored for a period of 1 day to 3.9 years (mean +/- S.D. = 1.39 +/- 1.10 years). Abnormal 201Tl uptake appeared to denote a subgroup of lesions with distinctly greater mortality and morbidity. Of 201Tl-positive patients, 17% died within the course of this study; no deaths occurred among the 201Tl-negative group. Other parameters of disease outcome also clearly separated the 201Tl-positive and 201Tl-negative groups, with the former demonstrating a 50% shorter period of recurrence-free survival from the time of diagnosis (two-tailed t test, P < 0.01). Significant enhancement with paramagnetic contrast agents paralleled 201Tl positivity in correlating with greater mortality but failed to predict duration of recurrence-free survival. The authors conclude that 201Tl activity provides significant predictive information of the expected biologic behavior of childhood brain tumors, both for duration of recurrence-free survival and for estimated life expectancy. This information complements and extends data provided by MRI enhancement patterns.

Tumor uptake of 99mTc-MIBI and 201Tl by a 9L gliosarcoma brain tumor model in rats

There have been several recent case reports of the accumulation of 99mTc-MIBI [hexakismethoxyisobutylisonitriletechnetium(I), Cardiolite, Sestamibi] in tumors, but no reports of the uptake of this radiopharmaceutical in an animal model. To address this question, the biodistributions of 99mTc-MIBI and 201Tl were compared in Fisher rats bearing 9L gliosarcomas. The results showed that, although the absolute uptake of the tracers by the tumor is relatively low (< 1% ID/g), the tumor-to-normal brain ratios are greater than 6:1 because of low uptake by normal brain. The tumor-to-normal brain ratio of 99mTc-MIBI exceeds that of other currently available 99mTc radiopharmaceuticals suggesting that 99mTc-MIBI may be of particular value in the clinical evaluation of brain tumors and that further investigation of this class of compounds as tumor-avid radiopharmaceuticals is necessary.

The radiological differentiation of acoustic neurinoma and meningioma occurring together in the cerebellopontine angle

A patient with right hearing loss, in whom computed tomographic scanning demonstrated a mass in the right cerebellopontine angle with widening of and extension into the internal auditory canal, but with important posterior extension and broad implantation on the surface of the petrous bone, is reported. On both T2-weighted and gadolinium-enhanced T1-weighted magnetic resonance images, there were clearly two separate tumoral lesions: an acoustic neurinoma extending into the internal auditory canal and a meningioma with broad implantation on the petrous apex. These findings were confirmed at surgery.