Reto Bale

68Ga-DOTA-Tyr3-Octreotide PET in Neuroendocrine Tumors: Comparison with Somatostatin Receptor Scintigraphy and CT

The aim of this study was to evaluate the diagnostic value of a new somatostatin analog, 68Ga-labeled 1,4,7,10-tetraazacyclododecane-N,N′,N″,N″′-tetraacetic acid-d-Phe1-Tyr3-octreotide (68Ga-DOTA-TOC), for PET in patients with known or suspected neuroendocrine tumors. PET was compared with conventional scintigraphy and dedicated CT. Methods: Eighty-four patients (48 men, 36 women; age range, 28–79 y; mean age ± SD, 58.2 ± 12.2 y) were prospectively studied. For analysis, patients were divided into 3 groups: detection of unknown primary tumor in the presence of clinical or biochemical suspicion of neuroendocrine malignancy (n = 13 patients), initial tumor staging (n = 36 patients), and follow-up after therapy (n = 35 patients). Each patient received 100–150 MBq 68Ga-DOTA-TOC. Imaging results of PET were compared with 99mTc-labeled hydrazinonicotinyl-Tyr3-octreotide (99mTc-HYNIC-TOC) and 111In-DOTA-TOC. CT was also performed on every patient using a multidetector scanner. Each imaging modality was interpreted separately by observers who were unaware of imaging findings before comparison with PET. The gold standard for defining true-positive (TP), true-negative (TN), false-positive (FP), and false-negative (FN) results was based on all available histologic, imaging, and follow-up findings. Results: PET was TP in 69 patients, TN in 12 patients, FP in 1 patient, and FN in 2 patients, indicating a sensitivity of 97%, a specificity of 92%, and an accuracy of 96%. The FP finding was caused by enhanced tracer accumulation in the pancreatic head, and the FN results were obtained in patients with a tumor of the gastrointestinal tract displaying liver metastases. 68Ga-DOTA-TOC showed higher diagnostic efficacy compared with SPECT (TP in 37 patients, TN in 12 patients, FP in 1 patient, and FN in 34 patients) and diagnostic CT (TP in 41 patients, TN in 12 patients, FP in 5 patients, and FN in 26 patients). This difference was of statistical significance (P < 0.001). However, the combined use of PET and CT showed the highest overall accuracy. Conclusion: 68Ga-DOTA-TOC PET shows a significantly higher detection rate compared with conventional somatostatin receptor scintigraphy and diagnostic CT with clinical impact in a considerable number of patients.

Bone Metastases in Patients with Neuroendocrine Tumor: 68Ga-DOTA-Tyr3-Octreotide PET in Comparison to CT and Bone Scintigraphy

Somatostatin receptor scintigraphy is an accurate imaging modality for the diagnosis of neuroendocrine tumor. Because detection of distant metastases has a major impact on treatment, early diagnosis of metastatic spread is of great importance. So far, no standard procedure has become established for the early diagnosis of bone metastases from neuroendocrine tumor. We compared the diagnostic value of CT with that of the novel somatostatin analog 68Ga-1,4,7,10-tetraazacyclododecane-N,N′,N″,N′′′-tetraacetic acid-d-Phe1-Tyr3-octreotide (68Ga-DOTATOC) in the detection of such metastases. Methods: Fifty-one patients (22 women and 29 men; age range, 32–87 y) with histologically verified neuroendocrine tumor were included in this study. PET scans were fused with CT scans using a vacuum fixation device. 18F-NaF or 99mTc-dicarboxypropane diphosphonate bone scans or clinical follow-up served as the reference standard. Results: Twelve of the 51 patients had no evidence of bone metastases on any of the available imaging modalities, and 37 patients had 68Ga-DOTATOC PET results true-positive for bone metastases. 68Ga-DOTATOC PET results were true-negative for 12 patients, false-positive for one, and false-negative for another, resulting in a sensitivity of 97% and a specificity of 92%. 68Ga-DOTATOC PET detected bone metastases at a significantly higher rate than did CT (P < 0.001). Furthermore, conventional bone scans confirmed the results of somatostatin receptor PET but did not reveal additional tumors in any patients. Conclusion: 68Ga-DOTATOC PET is a reliable, novel method for the early detection of bone metastases in patients with neuroendocrine tumor. Our results show that CT and conventional bone scintigraphy are less accurate than 68Ga-DOTATOC PET in the primary staging or restaging of neuroendocrine tumor.

68Ga-DOTA-Tyr3-Octreotide PET for Assessing Response to Somatostatin-Receptor–Mediated Radionuclide Therapy

68Ga-labeled 1,4,7,10-tetraazacyclododecane-N,N′,N′′,N′′′-tetraacetic acid-d-Phe1-Tyr3-octreotide (DOTA-TOC) PET has proven its usefulness in the diagnosis of patients with neuroendocrine tumors. Radionuclide therapy (90Y-DOTA-TOC or 177Lu-DOTA-octreotate) is a choice of treatment that also requires an accurate diagnostic modality for early evaluation of treatment response. Our study compared 68Ga-DOTA-TOC PET with CT or MRI using the Response Evaluation Criteria in Solid Tumors. Furthermore, standardized uptake values (SUVs) were calculated and compared with treatment outcome. Methods: Forty-six patients (29 men, 17 women; age range, 34–84 y) with advanced neuroendocrine tumors were investigated before and after 2–7 cycles of radionuclide therapy. Long-acting somatostatin analogs were not applied for at least 6 wk preceding the follow-up. Data were acquired with a dedicated PET scanner. Emission image sets were acquired at 90–100 min after injection. 68Ga-DOTA-TOC PET images were visually interpreted by 2 experienced nuclear medicine physicians. For comparison, multislice helical CT scans and 1.5-T MRI scans were obtained. Attenuation-corrected PET images were used to determine SUVs. Repeated CT evaluation and other imaging modalities, for example, 18F-FDG, were used as the reference standard. Results: According to the reference standard, 68Ga-DOTA-TOC PET and CT showed a concordant result in 32 patients (70%). In the remaining 14 patients (30%), discrepancies were observed, with a final outcome of progressive disease in 9 patients and remission in 5 patients. 68Ga-DOTA-TOC PET was correct in 10 patients (21.7%), including 5 patients with progressive disease. In these patients, metastatic spread was detected with the follow-up whole-body PET but was missed when concomitant CT was used. On the other hand, CT confirmed small pulmonary metastases not detected on 68Ga-DOTA-TOC in 1 patient and progressive liver disease not detected on 68Ga-DOTA-TOC in 3 patients. Quantitative SUV analysis of individual tumor lesions showed a large range of variability. Conclusion: 68Ga-DOTA-TOC PET shows no advantage over conventional anatomic imaging for assessing response to therapy when all CT information obtained during follow-up is compared. Only the development of new metastases during therapy was detected earlier in some cases when whole-body PET was used. SUV analysis of individual lesions is of no additional value in predicting individual responses to therapy.

Errors and error management in image-guided craniomaxillofacial surgery

Image-guided surgery is being increasingly used in craniomaxillofacial tumor surgery, trauma surgery, orthognathic surgery, and implant surgery. Compared with conventional procedure, treatment planning is performed on the computer based on previously obtained 3-dimensional imaging data, and the surgical procedure is carried out under guidance of a surgical navigation system. Accuracy is of vital importance for the clinical application of this sophisticated technology. All errors are integrative and depend on many factors, including image modality, registration technique, tracking technology, and application type. Knowledge of errors and error management is important to understand the possibilities and limitations of different image-guided surgical approaches. The aim of this review is to provide a comprehensive overview on the different errors and error management strategies in image-guided craniomaxillofacial surgery.

Successful surgical treatment of insular epilepsy with nocturnal hypermotor seizures

Nocturnal hypermotor seizures (NHSs) suggest seizure onset in the frontal lobe. We present a patient with NHSs and insular seizure onset who underwent successful surgical treatment.

Navigated CT-guided interventions.

Diagnostic and therapeutic CT‐ guided percutaneous interventions are clinical routine in interventional radiology. Image‐guided navigation systems visualize the internal anatomy during interventions in real time not necessitating continuous image acquisition. Although multiple 3D image‐guidance devices have been developed and used by several surgical disciplines in the last few years, they have not yet been fully applied by the interventional radiologist. The aim of this article is to review the currently performed methods of CT‐guided percutaneous interventions and to discuss the potential benefits of newly developed 3D‐ navigation systems.

Reproducibility of Patient Positioning for Fractionated Extracranial Stereotactic Radiotherapy Using a Double-Vacuum Technique

Background and Purpose:Precise reproducible patient positioning is a prerequisite for conformal fractionated radiotherapy. A fixation system based on double-vacuum technology is presented which can be used for conventional as well as hypofractionated stereotactic extracranial radiotherapy.Material and Methods:To form the actual vacuum mattress, the patient is pressed into the mattress with a vacuum foil which can also be used for daily repositioning and fixation. A stereotactic frame can be positioned over the region of interest on an indexed base plate. Repositioning accuracy was determined by comparing daily, pretreatment, orthogonal portal images to the respective digitally reconstructed radiographs (DRRs) in ten patients with abdominal and pelvic lesions receiving extracranial fractionated (stereotactic) radiotherapy. The three-dimensional (3-D) vectors and 95% confidence intervals (CI) were calculated from the respective deviations in the three axes. Time required for initial mold production and daily repositioning was also determined.Results:The mean 3-D repositioning error (187 fractions) was 2.5 ± 1.1 mm. The largest single deviation (10 mm) was observed in a patient treated in prone position. Mold production took an average of 15 min (10–30 min). Repositioning times are not necessarily longer than using no positioning aid at all.Conclusion:The presented fixation system allows reliable, flexible and efficient patient positioning for extracranial stereotactic radiotherapy.Hintergrund und Ziel:Voraussetzung für eine konformale fraktionierte Strahlentherapie ist eine präzise reproduzierbare Positionierung des Patienten und des Zielvolumens. Vorgestellt wird ein auf dem Doppelvakuumprinzip basierendes Fixationssystem, das sowohl für konventionelle als auch extrakranielle stereotaktische Bestrahlungen eingesetzt werden kann.Material und Methodik:Mittels einer Fixationsfolie, mit der er auch zusätzlich fixiert werden kann, wird der Patient vor der Abformung in die Vakuummatratze hineingepresst. Eine exakt auf einer indexierten Bodenplatte positionierbare Plexiglashaube dient als stereotaktischer Rahmen. Bei zehn Patienten mit Zielvolumina im Abdomen und Becken wurden vor jeder Bestrahlung orthogonale digitale Verifikationsaufnahmen angefertigt. Diese wurden mit den digital rekonstruierten Röntgenbildern (DRRs) des dreidimensionalen (3-D) Planungssystems verglichen. Aus den Abweichungen der drei Raumrichtungen wurden die 3-D-Vektoren als Maß für die Repositionierungsgenauigkeit errechnet.Ergebnisse:Der Mittelwert der für alle Patienten errechneten 3-D-Vektoren (187 Fraktionen) betrug 2,5 ± 1,1 mm. Der mit 10 mm größte 3-D-Vektor wurde bei einem in Bauchlage bestrahlten Patienten beobachtet. Die initiale Abformung dauerte im Durchschnitt 15 min (10–30 min). Der tägliche zeitliche Lagerungsaufwand am Bestrahlungsgerät ist nur unwesentlich länger als ohne Fixationshilfe.Schlussfolgerung:Das vorgestellte Fixierungssystem ermöglicht eine zuverlässige, flexible und effiziente Patientenpositionierung für die stereotaktische Bestrahlung extrakranieller Tumoren.

Ultrasound-guided and CT-navigation-assisted periradicular and facet joint injections in the lumbar and cervical spine: a new teaching tool to recognize the sonoanatomic pattern.

Background and Objectives The aim of this study is to provide a teaching tool to facilitate the acquirement of periradicular and facet-joint infiltration techniques in the cervical and lumbar spine. Methods On 3 fresh cadavers, a computed tomography (CT) of the lumbar and cervical region was obtained. By use of a dedicated image navigation and reconstruction system, sonographic images were generated and fused with the collected CT data set. Results The sonoanatomy can be instantly compared with the correlating CT-images. This new bimodal method allows for simultaneous views of CT and ultrasound images. Multiplanar imaging of ultrasound-guided infiltrations is facilitated. Conclusions This teaching tool provides immediate CT-verification of sonographically identified structures and helps in the identification of bony landmarks, which are necessary for facet-joint and periradicular injections.

Frameless Stereotactic Cannulation Of The Foramen Ovale For Ablative Treatment Of Trigeminal Neuralgia

OBJECTIVE: Ablative neurosurgical treatment of trigeminal neuralgia, including percutaneous radiofrequency thermocoagulation, requires cannulation of the foramen ovale. To maximize patient security and cannulation success, a frameless stereotactic system was evaluated in a phantom study, a cadaveric study, and a preliminary clinical trial. METHODS: Frameless stereotaxy using an optical navigation system, an aiming device, and a noninvasive vacuum mouthpiece-based registration and patient fixation technique was used for the targeting of a test body based on 1-, 3-, and 5-mm axial computed tomographic slices and of the foramen ovale in three cadavers and 15 patients based on 3-mm axial computed tomographic slices. RESULTS: The mean normal (x/y) localization accuracy/standard deviation (n = 360) was 1.31/0.67 mm (1-mm slices), 1.38/0.65 mm (3-mm slices), and 1.84/0.96 mm (5-mm slices). Significantly better results were achieved with 1- and 3-mm slices when compared with 5-mm slices (P < 0.001). The foramen ovale (3 × 6 mm) was successfully cannulated at the first attempt in all cadavers and patients, which indicates clinical localization accuracies better than 1.5 mm in the anteroposterior and 3 mm in the medial-lateral directions. CONCLUSION: Based on the noninvasive Vogele-Bale-Hohner vacuum mouthpiece, there is no need for invasive head clamp fixation. Imaging, real laboratory simulation, and the actual surgical intervention can be separated in time and location. The presented data suggest that frameless stereotaxy is a predictable and reproducible procedure, which may enhance patient security and cannulation success independent of the surgeon’s experience.

A Simple and Non-Invasive Vacuum Mouthpiece-Based Head Fixation System for High Precision Radiotherapy

Purpose: To demonstrate why conventional non-invasive mouthpiece-based fixation has not achieved the expected accuracy and to suggest a solution of the problem. Patients and Methods: The Vogele Bale Hohner (VBH) head holder is a non-invasive vacuum mouthpiece-based head fixation system. Feasibility and repositioning accuracy were evaluated by portal image analysis in 12 patients with cranial tumors intended for stereotactic procedures, fixated with the newest version (VBH HeadFix-ARC®). Results: Portal image analysis (8 patients evaluated in 2-D, 4 patients in 3-D) showed that even in routine external beam radiation therapy, treatment can be applied to within a mean 2-D and 3-D accuracy of under 2 mm (SD 0.92 mm and 1.2 mm, respectively) with cost and repositioning time per patient and patient comfort comparable to that of common thermoplastic masks. Conclusion: These preliminary results show that high repositioning accuracy does not rule out simple and quick application and patient comfort. Paramount, however, is tensionless repositioning via the vacuum mouthpiece.Ziel: Fixationssysteme, die auf konventionellen (nicht Vakuum-)Mundstücken basieren, erreichen oftmals nicht die erwartete Genauigkeit. Die vorliegende Arbeit beschäftigt sich mit den möglichen Ursachen und bietet entsprechende Lösungen. Patienten und Methoden: Der Vogele-Bale-Hohner-(VBH-)Head-Holder ist ein nicht invasives, auf einem Vakuummundstück (Abbildung 1) basierendes Kopffixationssystem (Abbildungen 2 und 3). Bei zwölf Patienten mit kraniellen Tumoren wurde mit der neuesten Version (VBH HeadFix-ARC®) die Repositionsgenauigkeit mittels Portal Imaging untersucht. Ergebnisse: Die Portal-Imaging-Auswertung (acht Patienten in 2-D, vier Patienten in 3-D) bestätigte, dass eine Bestrahlung im Kopfbereich auch in der klinischen Routine mit einer mittleren Genauigkeit von unter 2 mm (Standardabweichung 0,92 bzw. 1,2 mm) appliziert werden kann, während Kosten, Repositionsdauer und Akzeptanz der Patienten vergleichbar sind mit denen thermoplastischer Masken. Schlussfolgerung: Diese vorläufigen Ergebnisse zeigen, dass eine hohe Repositionierungsgenauigkeit ein einfaches, schnelles und für den Patienten angenehmes System nicht ausschließt. Ausschlaggebend ist die spannungsfreie Lagerung mittels Vakuummundstück.