Impact of the surgical strategy on the incidence of C5 nerve root palsy in decompressive cervical surgery.

OBJECTIVE: Our aim was to identify the impact of different surgical strategies on the incidence of C5 palsy. BACKGROUND: Degenerative cervical spinal stenosis is a steadily increasing morbidity in the ageing population. Postoperative C5 nerve root palsy is a common complication with severe impact on the patients´ quality of life. METHODS: We identified 1708 consecutive patients who underwent cervical decompression surgery due to degenerative changes. The incidence of C5 palsy and surgical parameters including type and level of surgery were recorded to identify predictors for C5 nerve palsy. RESULTS: The overall C5 palsy rate was 4.8%, with 18.3% of cases being bilateral. For ACDF alone the palsy rate was low (1.13%), compared to 14.0% of C5 palsy rate after corpectomy. The risk increased with extension of the procedures. Hybrid constructs with corpectomy plus ACDF at C3-6 showed significantly lower rates of C5 palsy (10.7%) than corpectomy of two vertebrae (p = 0.005). Multiple regression analysis identified corpectomy of C4 or C5 as a significant predictor. We observed a lower overall incidence for ventral (4.3%) compared to dorsal (10.9%) approaches (p<0.001). When imaging detected a postoperative shift of the spinal cord at index segment C4/5, palsy rate increased significantly (33.3% vs. 12.5%, p = 0.034). CONCLUSIONS: Extended surgical strategies, such as dorsal laminectomies, multilevel corpectomies and procedures with extensive spinal cord shift were shown to display a high risk of C5 palsy. The use of extended procedures should therefore be employed cautiously. Switching to combined surgical methods like ACDF plus corpectomy can reduce the rate of C5 palsy.

Impact of spinal cord compression from intradural and epidural spinal tumors on perioperative symptoms-implications for surgical decision making.

Spinal cord or cauda equina compression (SCC) is an increasing challenge in clinical oncology due to a higher prevalence of long-term cancer survivors. Our aim was to determine the clinical relevance of SCC regarding patient outcome depending on different tumor entities and their anatomical localization (extradural/intradural/intramedullary). We retrospectively analyzed 230 patients surgically treated for SCC. Preoperative status for pain and neurological impairment were correlated to the degree of compression, tumor location, and early as well as short-term follow-up outcome parameters. Interestingly, we did not observe any differences between intradural-extramedullary compared to extradural tumors. Unilaterally localized tumors were likely to present with pain (72.9 %, p < 0.01), whereas concentric growth was associated with motor deficits (41.0 %, p < 0.01, as primary symptom, 49.3 % on admission, p < 0.05). In concentric tumors, the pain pattern was diffuse (40.5 % vs. 17.5 in unilateral disease, p < 0.01), whereas unilateral tumors resulted in localized pain (61.4 % local axial or radicular, p < 0.01). Diffuse pain, patients without a sensory or motor deficit, progressive disease, cervical localization, and a higher degree of stenosis were identified as beneficial for an early improvement in pain (p < 0.05). Notably, 29 % of patients with unchanged pain and 30.8 % with unchanged neurologic function at day 7 postoperative improved during follow-up (p < 0.001). Our data demonstrate that the preoperative tumor anatomy in patients with SCC was closely related to their presenting symptoms and early clinical outcome. The detailed analysis elucidates the biology of SCC and might thereby aid in determining which patients will benefit from surgery.

Value of 18 F-FDG PET/MRI for the outcome of CT-guided facet block therapy in cervical facet syndrome: initial results.

INTRODUCTION: The aim of this study was to evaluate the ability of 18 F-fluorodeoxyglucose positron emission tomography/magnetic resonance imaging (18 F-FDG PET/MRI) to detect PET-positive cervical facet arthropathy and identify patients who benefit from facet block therapy. METHODS: Ten patients with cervical facet syndrome (mean age: 65 ± 12 years) underwent 18 F-FDG PET/MRI of the neck. Focal 18 F-FDG uptake in PET-positive facet joints served as target for computed tomography (CT)-guided facet blocks. In PET-negative patients, the target joint for facet block therapy was selected by current clinical standards considering the level of maximum facet arthrosis and pain. Neck pain was measured on visual analogue scale (VAS) before and after therapy. Bone marrow signal intensity (SI) ratio on turbo inversion recovery magnitude (TIRM) images and maximum standard uptake values (SUVmax) was calculated for each facet joint. Pearson's correlation coefficient (r) was calculated between bone marrow SI ratios on TIRM and SUVmax. RESULTS: 18 F-FDG PET/MRI detected PET-positive facet arthropathy in six patients. Patients with PET-positive facet arthropathy had significantly less pain compared with the pretreatment pain 3 h (P = 0.002), 4 weeks (P = 0.002) and 3 months (P = 0.026) after facet block therapy. Pain did not change significantly in patients with PET-negative facet arthropathy. TIRM SI ratio was higher in PET-positive facet arthropathy than in PET-negative facet arthropathy (P < 0.001). Correlation was strong between bone marrow SI ratio on TIRM images and SUVmax (r = 0.7; P < 0.001). CONCLUSIONS: 18 F-FDG PET/MRI can detect PET-positive cervical facet arthropathy and help to identify patients benefitting from facet block therapy. Bone marrow TIRM SI ratio might be a surrogate for PET-positive facet arthropathy.

Recurrent spinal metastasis of a sporadic medullary carcinoma of the thyroid after radiation therapy: a case report and review of the literature.

Sporadic Medullary Carcinoma of the Thyroid is a relatively uncommon entity and at the time of diagnosis, most already present loco-regional metastasis. Therapy should be aggressive to reduce recurrence and mortality. Follow-up period should continue lifelong and should also include calcium/pentagastrin infusion test, as well as 6-month interval diagnostic imaging.

Treatment of large thoracic and lumbar paraspinal schwannoma.

BACKGROUND: Paraspinal neurogenic tumors usually expand into the mediastinum and retroperitoneum and can reach a considerable size before they become symptomatic. Such large tumors are rare. We describe 14 cases of large schwannomas (>2.5 cm ø) with mild and late onset of symptoms, which were treated with total surgical resection through a single-approach surgery. METHODS: In 2013 14 patients with paraspinal large schwannomas were treated in our institutions. Data were analyzed retrospectively. Magnetic resonance imaging (MRI) showed lesions suspicious for a paraspinal schwannoma with partial intraforaminal growth. In case of ambiguity regarding tumor dignity, a needle biopsy was performed before final treatment. Three different approaches and their indications were discussed. RESULTS: Fourteen patients (7 female and 7 male, ages 18-58 years, mean: 39.8 years) requiring surgical exploration because of a thoracic (6) or lumbar/lumbosacral (8) lesion were treated in our institutions. Two patients received CT-guided needle biopsy preoperatively. Complete resection of the schwannoma was possible through a mini-thoracotomy in 1 case (7 %), a retroperitoneal approach in 2 cases (14 %), and dorsal interlaminar and intercostal fenestration in 11 cases (79 %). Histological examination revealed the diagnosis of schwannoma (WHO grade I) in all cases except one with neurofibroma (WHO grade I). There were no major complications in any case. CONCLUSION: Large benign schwannomas are rare. They need a tailored treatment, which in most cases works through one surgical approach. Usually it is possible to perform a complete resection with a good postoperative prognosis.

Open microsurgical tumor excavation and vertebroplasty for metastatic destruction of the second cervical vertebra-outcome in seven cases.

BACKGROUND CONTEXT: Metastatic osteolytic involvement of the second cervical vertebra (C2) is rare, but usually very painful. Percutaneous vertebroplasty has shown to be effective regarding pain control, but carries the risk of cement leakage. PURPOSE: To describe an alternative microsurgical procedure suitable for patients suffering from C2 osteolysis who are considered to be high risk with respect to cement leakage. STUDY DESIGN: A technical report. PATIENT SAMPLE: It included seven patients. OUTCOME MEASURES: They include the assessment of clinical safety regarding approach- and procedure-related morbidity and radiologic safety regarding extravertebral cement leakage and the assessment of clinical efficacy by monitoring the pain activity using the visual analog scale (VAS). MATERIALS AND METHODS: Seven patients (five men, two women; mean age 70 years) presented with an acute onset of excruciating neck pain (VAS>6) due to osteolytic destruction of the axis vertebra. There was no neurologic deficit and no compression of the spinal cord preoperatively requiring surgical decompression or stabilization in any of the cases. An open treatment strategy via an anterolateral microsurgical approach was performed. Under biplanar fluoroscopic control, the soft tumor tissue was resected out of the vertebral body through a drilled entry in the anterior wall. After the excavation procedure, the resection cavity was filled with minimal pressure with polymethylmethacrylate bone cement. RESULTS: All patients suffered from severe spontaneous neck pain (mean VAS 8.1, range 6-9), with head motion-dependent pain exacerbation despite high dose of opiates and fixation of the head with a brace.Mean duration of the operative procedure was 51 minutes. Histologic analysis revealed a diagnosis of cancer metastasis in all cases. On average, 1.9 mL cement was placed within the vertebral body, and no cement leakage was observed in postoperative computed tomography and X-ray controls. All patients experienced immediate pain relief at Day 1 after the procedure (mean VAS 4.0, range 2-6), and a further decrease of pain levels was observed at Week 6 after the completion of radiation therapy (mean VAS 2.0, range 0-5). CONCLUSIONS: In cases of metastatic C2 destruction, tumor excavation via an anterolateral approach and subsequent filling of the resection cavity with bone cement offers a safe and effective alternative to percutaneous approaches.

Hypermetabolism in 18F-FDG PET predicts favorable outcome following decompressive surgery in patients with degenerative cervical myelopathy.

UNLABELLED: The aim of this study was to prospectively assess the regional changes of glucose metabolism of the cervical spinal cord in patients with degenerative cervical spine stenosis and symptomatic cervical myelopathy after decompressive surgery using (18)F-FDG PET. METHODS: Twenty patients with symptomatic degenerative monosegmental cervical stenosis with neuroradiologic signs of spinal cord compression underwent decompressive surgery. The clinical course using a functional status score (Japanese Orthopedic Association [JOA] score), (18)F-FDG uptake, and MR imaging were assessed before and at follow-up 12 mo after surgery. Pre- and postoperative changes of (18)F-FDG PET were correlated to the patients' clinical outcome. RESULTS: Ten patients demonstrated preoperatively a focally increased (18)F-FDG uptake at the level of the stenosis. At follow-up, the uptake declined significantly (P = 0.008), and a significant improvement of JOA scores (P < 0.001) could be observed. The remaining 10 patients were characterized preoperatively by an inconspicuous glucose uptake at the level of cord compression in combination with a poststenotic decrease of (18)F-FDG uptake. At follow-up, both JOA scores and (18)F-FDG uptake changed insignificantly. CONCLUSION: Focal glucose hypermetabolism at the level of cervical spinal cord compression may predict an improved outcome after surgical decompression. Thus, this finding on (18)F-FDG PET suggests a functional damage in a reversible phase of cervical myelopathy.

Transtubular microsurgical approach to treating extraforaminal lumbar disc herniations.

OBJECT: Approaches to treating extraforaminal lumbar disc herniations can be challenging due to the unique anatomy and the need to prevent spinal instability. Numerous approaches, including conventional midline, paramedian, minimally invasive, and full endoscopic approaches, have been described. The purposes of this study were to point out the outcome and clinical advantages of a transtubular microsurgical approach and to describe and illustrate this technique. METHODS: Between 2009 and 2012, a series of 51 patients underwent a minimally invasive dilative transtubular microsurgical approach for the treatment of extraforaminal lumbar disc herniations. All patients were clinically evaluated using the visual analog scale (VAS) and Oswestry Disability Index preoperatively and 6 months postoperatively. RESULTS: Both pain scores and functional status showed significant improvement after surgery (p < 0.001): radicular pain decreased from VAS score of 7.9 to one of 1.3, lower back pain from VAS score of 2.4 to 1.4, and the Oswestry Disability Index from 42.0 to 12.3. Subgroup analyses revealed no differences in outcome regarding obesity or timing of surgery (early vs late intervention). Highly significant was the correlation between preoperative radicular pain activity and timing of surgical intervention (p < 0.001). CONCLUSIONS: The dilative transtubular microsurgical approach combines the advantages of the conventional open muscle-splitting approach and the endoscopic approach. The technique is easy to use with a steep learning curve. Less muscle trauma and the absence of bony resection prevent facet pain and instability, thereby contributing to a rapid recovery. Patients in this series improved excellently in the short-term follow-up.

Clinical value of 2-deoxy-[18F]fluoro-D-glucose positron emission tomography in patients with cervical spondylotic myelopathy.

Cervical spondylotic myelopathy (CSM) is one of the most common spinal cord disorders in the elderly. It is usually diagnosed by MRI, but in a significant number of patients the clinical course of CSM does not correlate with the extent of the spinal cord compression. Recent studies have suggested that a distinct metabolic pattern of the cervical cord, as assessed by PET with 2-deoxy-[(18)F]fluoro-D-glucose ((18)F-FDG) may predict a patient's clinical outcome after decompressive surgery for cervical spine stenosis. The authors provide an overview of the recent literature regarding the value of PET with (18)F-FDG of the cervical cord in patients with CSM, paying attention to prognostic aspects and the potential role of inflammatory processes in the acute phase of the disease.

Clinical value of O-(2-[(18)F]-fluoroethyl)-L-tyrosine positron emission tomography in patients with low-grade glioma.

Progress in morphological imaging has facilitated the diagnosis of low-grade glioma (LGG) and plays a decisive role in therapeutic decisions. To date, the method of choice is contrast-enhanced MRI including T1-/T2-weighted and FLAIR sequences. However, tumor delineation and the differentiation between neoplastic and normal brain tissue can be difficult when using morphological MRI and may complicate the identification of anaplastic foci for biopsy and further treatment planning. Furthermore, therapy monitoring and the differentiation of tumor recurrence from unspecific post-therapeutic changes in the tissue are challenging. Additional information about tumor metabolism may be very helpful for the diagnostic assessment of LGG and can be provided by PET. In recent years, the PET amino acid tracer O-(2-[(18)F]-fluoroethyl)-L-tyrosine ((18)F-FET) has been clinically validated for brain tumor diagnosis. This tracer has logistical advantages over the widely used PET tracer (11)C-methyl-L-methionine due to the longer half-life of the (18)F-label (109 vs 20 minutes, respectively). Additionally, it has been demonstrated that both tracers provide comparable diagnostic information. The authors provide an overview of the recent literature regarding the value of various clinical applications of (18)F-FET PET in patients with LGG.

The impact of fluorescence guidance on spinal intradural tumour surgery.

PURPOSE: 5-Aminolevulinic acid (5-ALA)-based fluorescence-guided surgery was shown to be beneficial for cerebral malignant gliomas. Extension of this technique for resection of meningiomas and cerebral metastasis has been recently evaluated. Aim of the present study is to evaluate the impact of fluorescence-guided surgery in spinal tumor surgery. METHODS: Twenty-six patients with intradural spinal tumors were included in the study. 5-ALA was administered orally prior to the induction of anesthesia. Intraoperative, 440 nm fluorescence was applied after exploration of the tumor and, if positive, periodically during and at the end of resection to detect tumor-infiltrated sites. RESULTS: Tumors of WHO grade III and IV were found in five patients. In detail intra- or perimedullary metastasis of malignant cerebral gliomas was found including glioblastoma WHO grade IV (n = 2), anaplastic astrocytoma WHO grade III (n = 1), anaplastic oligoastrocytoma WHO grade III (n = 1). In addition, one patient suffered from a spinal drop metastasis of a cerebellar medulloblastoma WHO grade IV. Tumors of WHO grade I were diagnosed in 18 patients: Eight cases of meningioma (two recurrences), six cases of neurinoma, one neurofibroma, two ependymoma and one plexus papilloma. At least, benign pathologies were histologically proven in three patients. All four spinal metastasis of malignant glioma (100 %), seven of eight meningiomas (87.5 %) and one of two ependymoma (50 %) were found to be ALA-positive. CONCLUSION: The present study demonstrates that spinal intramedullary gliomas and the majority of spinal intradural meningiomas are 5-ALA positive. As a surgical consequence, especially in intramedullary gliomas, the use of 5-ALA fluorescence seems to be beneficial.

Diagnostic performance of 18F-FET PET in newly diagnosed cerebral lesions suggestive of glioma.

UNLABELLED: The aim of this study was to assess the clinical value of O-(2-(18)F-fluoroethyl)-l-tyrosine ((18)F-FET) PET in the initial diagnosis of cerebral lesions suggestive of glioma. METHODS: In a retrospective study, we analyzed the clinical, radiologic, and neuropathologic data of 174 patients (77 women and 97 men; mean age, 45 ± 15 y) who had been referred for neurosurgical assessment of unclear brain lesions and had undergone (18)F-FET PET. Initial histology (n = 168, confirmed after surgery or biopsy) and the clinical course and follow-up MR imaging in 2 patients revealed 66 high-grade gliomas (HGG), 77 low-grade gliomas (LGG), 2 lymphomas, and 25 nonneoplastic lesions (NNL). In a further 4 patients, initial histology was unspecific, but during the course of the disease all patients developed an HGG. The diagnostic value of maximum and mean tumor-to-brain ratios (TBR(max/)TBR(mean)) of (18)F-FET uptake was assessed using receiver-operating-characteristic (ROC) curve analyses to differentiate between neoplastic lesions and NNL, between HGG and LGG, and between high-grade tumor (HGG or lymphoma) and LGG or NNL. RESULTS: Neoplastic lesions showed significantly higher (18)F-FET uptake than NNL (TBR(max), 3.0 ± 1.3 vs. 1.8 ± 0.5; P < 0.001). ROC analysis yielded an optimal cutoff of 2.5 for TBR(max) to differentiate between neoplastic lesions and NNLs (sensitivity, 57%; specificity, 92%; accuracy, 62%; area under the curve [AUC], 0.76; 95% confidence interval [CI], 0.68-0.84). The positive predictive value (PPV) was 98%, and the negative predictive value (NPV) was 27%. ROC analysis for differentiation between HGG and LGG (TBR(max), 3.6 ± 1.4 vs. 2.4 ± 1.0; P < 0.001) yielded an optimal cutoff of 2.5 for TBR(max) (sensitivity, 80%; specificity, 65%; accuracy, 72%; AUC, 0.77; PPV, 66%; NPV, 79%; 95% CI, 0.68-0.84). Best differentiation between high-grade tumors (HGG or lymphoma) and both NNL and LGG was achieved with a TBR(max) cutoff of 2.5 (sensitivity, 79%; specificity, 72%; accuracy, 75%; AUC, 0.79; PPV, 65%; NPV, 84%; 95% CI, 0.71-0.86). The results for TBR(mean) were similar with a cutoff of 1.9. CONCLUSION: (18)F-FET uptake ratios provide valuable additional information for the differentiation of cerebral lesions and the grading of gliomas. TBR(max) of (18)F-FET uptake beyond the threshold of 2.5 has a high PPV for detection of a neoplastic lesion and supports the necessity of an invasive procedure, for example, biopsy or surgical resection. Low (18)F-FET uptake (TBR(max) < 2.5) excludes a high-grade tumor with high probability.

Prognostic value of 18F-FDG PET in monosegmental stenosis and myelopathy of the cervical spinal cord.

UNLABELLED: MRI offers perfect visualization of spondylotic stenosis of the cervical spine, but morphologic imaging does not correlate with clinical symptoms and postoperative recovery after decompression surgery. In this prospective study, we investigated the role of (18)F-FDG PET in patients with degenerative stenosis of the cervical spinal cord in relation to postsurgical outcome. METHODS: Twenty patients with monosegmental spondylotic stenosis of the middle cervical spine (C3/C4 or C4/C5) showing intramedullary hyperintensity on T2-weighted MRI and clinical symptoms of myelopathy (myelopathic patients) were investigated by (18)F-FDG PET. Maximum standardized uptake values (SUV(max)) were measured at all levels of the cervical spine (C1-C7). Decompression surgery and anterior cervical fusion were performed on all patients, and clinical status (Japanese Orthopedic Association [JOA] score) was assessed before and 6 mo after surgery. The (18)F-FDG data of 10 individuals without cervical spine pathology were used as a reference (controls). RESULTS: The myelopathic patients showed a significant decrease in (18)F-FDG uptake in the area of the lower cervical cord, compared with the control group (C7 SUV(max), 1.49 ± 0.18 vs. 1.71 ± 0.27, P = 0.01). Ten myelopathic patients exhibited focally increased (18)F-FDG uptake at the level of the stenosis (SUV(max), 2.27 ± 0.41 vs. 1.75 ± 0.22, P = 0.002). The remaining 10 patients showed inconspicuous (18)F-FDG uptake at the area of the stenosis. Postoperatively, the patients with focally increased (18)F-FDG accumulation at the level of stenosis showed good clinical recovery and a significant improvement in JOA scores (13.6 ± 2.3 vs. 9.5 ± 2.5, P = 0.001), whereas no significant improvement was observed in the remaining patients (JOA score, 12.0 ± 2.4 vs. 11.6 ± 2.5, not statistically significant). Multiple regression analysis identified the presence of focally increased (18)F-FDG uptake at the level of the stenosis as an independent predictor of postoperative outcome (P = 0.002). CONCLUSION: The results suggest that regional changes in (18)F-FDG uptake have prognostic significance in compression-induced cervical myelopathy that may be helpful in decisions on the timing of surgery.

Finding the anaplastic focus in diffuse gliomas: the value of Gd-DTPA enhanced MRI, FET-PET, and intraoperative, ALA-derived tissue fluorescence.

OBJECTIVE: Diffuse gliomas may harbor anaplastic foci which affect prognosis and determine adjuvant therapies. Such foci are not always detected by contrast-enhancement on MRI. Recently, other modalities have been introduced, such as FET-PET for pre-diagnostic imaging and 5-aminolevulinic derived tumor fluorescence for intraoperative identification of malignant glioma tissue. The relationship between these modalities and their value for guiding biopsies during resection has not yet been elucidated in the group of diffuse gliomas. METHODS: FET-PET was performed in 30 consecutive patients with intracerebral lesions suggestive of diffuse gliomas on MRI with or without areas of contrast-enhancement. Prior to surgery patients were given 5-ALA at a dose of 20mg/kg body weight. Areas of FET uptake with a lesion/brain ratio of 1.6 or more were considered indicators of tumor. FET-PET data were corregistered with MRI data before surgery in order to obtain neuronavigated biopsies during resection, which were collected from FET positive and negative areas, analyzed for tumor fluorescence and correlated to contrast-enhancement on MRI. RESULTS: 13 of 30 tumors were diagnosed as gliomas WHO Grade II, 15 as gliomas WHO Grade III and 2 as gliomas WHO Grade IV. The mean lesion/brain tissue ratio of FET uptake was significantly greater for high-grade than for low-grade gliomas (averages SD 2.323±0.754 vs. 1.453±0.538 p=0.0014). A match of FET-pos/ALA-pos biopsies was found in 70.6% (12/17) of high-grade gliomas (WHO Grade III/IV) but only in 7.7% (1/13) of low grade gliomas. Gd-neg/FET-neg/ALA-neg biopsies yielded a low-grade tumor in 46.2% (6/13). A mismatch between FET uptake and 5-ALA (FET-pos/ALA-neg) was found in 46.2% (6/13) of the low-grade and in 17.6% (3/17) of the high-grade tumors. The combination of FET-PET- and 5-ALA-positivity yielded a sensitivity for identifying high-grade glioma foci of 70.5% and a specificity of 92.3%. CONCLUSIONS: In low grade gliomas 5-ALA fluorescence is the exception and FET PET is more sensitive. High grade areas in diffuse gliomas with anaplastic foci usually fluoresce, if they are FET PET positive. As a result, FET PET appears valuable for pre-operative identification of anaplastic foci and hot spots are strongly predictive for ALA-derived fluorescence, which highlight anaplastic foci during resection.

Comparison of (18)F-FET and (18)F-FDG PET in brain tumors.

UNLABELLED: The purpose of this study was to compare the diagnostic value of positron emission tomography (PET) using [(18)F]-fluorodeoxyglucose ((18)F-FDG) and O-(2-[(18)F]fluoroethyl)-l-tyrosine ((18)F-FET) in patients with brain lesions suspicious of cerebral gliomas. METHODS: Fifty-two patients with suspicion of cerebral glioma were included in this study. From 30 to 50 min after injection of 180 MBq (18)F-FET, a first PET scan ((18)F-FET scan) was performed. Thereafter, 240 MBq (18)F-FDG was injected and a second PET scan was acquired from 30 to 60 min after the second injection ((18)F-FET/(18)F-FDG scan). The cerebral accumulation of (18)F-FDG was calculated by decay corrected subtraction of the (18)F-FET scan from the (18)F-FET/(18)F-FDG scan. Tracer uptake was evaluated by visual scoring and by lesion-to-background (L/B) ratios. The imaging results were compared with the histological results and prognosis. RESULTS: Histology revealed 24 low-grade gliomas (LGG) of World Health Organization (WHO) Grade II and 19 high-grade gliomas (HGG) of WHO Grade III or IV, as well as nine others, mainly benign histologies. The gliomas showed increased (18)F-FET uptake (>normal brain) in 86% and increased (18)F-FDG uptake (>white matter) in 35%. (18)F-FET PET provided diagnostically useful delineation of tumor extent while this was impractical with (18)F-FDG due to high tracer uptake in the gray matter. A local maximum in the tumor area for biopsy guidance could be identified with (18)F-FET in 76% and with (18)F-FDG in 28%. The L/B ratios showed significant differences between LGG and HGG for both tracers but considerable overlap so that reliable preoperative grading was not possible. A significant correlation of tracer uptake with overall survival was found with (18)F-FDG only. In some benign lesions like abscesses, increased uptake was observed for both tracers indicating a limited specificity of both techniques. CONCLUSIONS: (18)F-FET PET is superior to (18)F-FDG for biopsy guidance and treatment planning of cerebral gliomas. The uptake of (18)F-FDG is associated with prognosis, but the predictive value is limited and a histological evaluation of tumor tissue remains necessary. Therefore, amino acids like (18)F-FET are the preferred PET tracers for the clinical management of cerebral gliomas.

Prognostic value of O-(2-18F-fluoroethyl)-L-tyrosine PET and MRI in low-grade glioma.

UNLABELLED: In glioma of World Health Organization (WHO) grade II (low-grade glioma), the natural course of a particular patient is not predictable and the treatment strategy is controversial. We determined prognostic factors in adult patients with untreated, nonenhancing, supratentorial low-grade glioma with special regard to PET using the amino acid O-(2-(18)F-fluoroethyl)-L-tyrosine ((18)F-FET) and MRI. METHODS: In a prospective study, baseline (18)F-FET PET and MRI analyses were performed on 33 consecutive patients with histologically confirmed low-grade glioma. None of the patients had radiation or chemotherapy. Clinical, histologic, therapeutic (initial cytoreduction vs. biopsy), (18)F-FET uptake, and MRI morphologic parameters were analyzed for their prognostic significance. Statistical endpoints were clinical or radiologic tumor progression, malignant transformation to glioma of WHO grade III or IV (high-grade glioma), and death. RESULTS: Baseline (18)F-FET uptake and a diffuse versus circumscribed tumor pattern on MRI were highly significant predictors of prognosis (P < 0.01). By the combination of these prognostically significant variables, 3 major prognostic subgroups of low-grade glioma patients could be identified. The first of these subgroups was patients with circumscribed low-grade glioma on MRI without (18)F-FET uptake (n = 11 patients, progression in 18%, no malignant transformation and no death). The second subgroup was patients with circumscribed low-grade glioma with (18)F-FET uptake (n = 13 patients, progression in 46%, malignant transformation to a high-grade glioma in 15%, and death in 8%). The third subgroup was patients with diffuse low-grade glioma with (18)F-FET uptake (n = 9 patients, progression in 100%, malignant transformation to a high-grade glioma in 78%, and death in 56%). CONCLUSION: We conclude that baseline amino acid uptake on (18)F-FET PET and a diffuse versus circumscribed tumor pattern on MRI are strong predictors for the outcome of patients with low-grade glioma.

[Improved diagnostics of cerebral gliomas using FET PET]. / Verbesserte Diagnostik von zerebralen Gliomen mit der FET PET.

Positron emission tomography (PET) using radiolabeled amino acids has shown great potential for more accurate diagnostics of cerebral gliomas. O-(2-[18F]Fluoroethyl)-L-tyrosine (FET) is a new tracer for PET which can be produced with high efficiency and distributed on a wide clinical scale in Germany. In a biopsy-controlled study, a significant improvement of the detection of true tumor extent of cerebral gliomas could be demonstrated by the combined use of FET PET and MRT in comparison with MRT alone. Advantages of FET PET are an improved guidance of biopsies, an improved planning of surgery and radiation therapy, and the differentiation of tumor recurrence from unspecific post-therapeutic tissue changes. Furthermore, FET PET appears to be particularly valuable in the prognosis of low-grade gliomas.

18F-FET PET differentiation of ring-enhancing brain lesions.

UNLABELLED: The aim of this study was to explore the differential diagnostic value of PET using the amino acid O-(2-(18)F-fluoroethyl)-L-tyrosine ((18)F-FET) in patients with newly diagnosed solitary intracerebral lesions showing ring enhancement on contrast-enhanced MRI. METHODS: (18)F-FET PET analyses were performed on 14 consecutive patients with intracerebral ring-enhancing lesions. Eleven of the patients were additionally studied with (18)F-FDG PET. In all patients, the main differential diagnosis after MRI was a malignant lesion, in particular glioblastoma multiforme, versus a benign lesion, in particular brain abscess. A malignant tumor was suspected for lesions showing increased (18)F-FET uptake on PET images with a mean lesion-to-brain ratio of at least 1.6 ((18)F-FET PET positive). A nonneoplastic lesion was suspected in cases of minimal or absent (18)F-FET uptake, with a mean lesion-to-brain ratio of less than 1.6 ((18)F-FET PET negative). Histologic diagnosis was obtained by serial biopsies in 13 of the 14 patients. One patient refused the biopsy, but follow-up indicated an abscess because his lesion regressed under antibiotic therapy. RESULTS: Histology and clinical follow-up showed high-grade malignant gliomas in 5 patients and nonneoplastic lesions in 9 patients. The findings of (18)F-FET PET were positive in all 5 glioma patients and in 3 of 9 patients with nonneoplastic lesions, including 2 patients with brain abscesses and 1 patient with a demyelinating lesion. The findings of (18)F-FDG PET were positive (mean lesion-to-gray matter ratio > or = 0.7) in 4 of 4 glioma patients and 3 of 7 patients with nonneoplastic lesions. CONCLUSION: Although (18)F-FET PET has been shown to be valuable for the diagnostic evaluation of brain tumors, our data indicate that, like (18)F-FDG PET, (18)F-FET PET has limited specificity in distinguishing between neoplastic and nonneoplastic ring-enhancing intracerebral lesions. Thus, histologic investigation of biopsy specimens remains mandatory to make this important differential diagnosis.