Jonas A. Castelijns

The incidence of micrometastases in neck dissection specimens obtained from elective neck dissections

Although modern imaging techniques become more accurate for the assessment of lymph node metastases in the neck as criteria and technology evolve, micrometastases remain occult with any technique. Even the routine histopathological examination of neck dissection specimens is unable to detect all micrometastases. Because knowledge on the incidence of micrometastases in the clinically N0 neck might be of importance for decision making regarding elective treatment, a retrospective study on 96 elective neck dissections was conducted. Meticulous histopathological examination of the neck dissection specimens yielded 3092 lymph nodes of which 67 (2.2%) were tumor‐positive. Twenty‐six of these 67 lymph node metastases were micrometastases. Of the 36 tumor‐positive neck dissection specimens, 21 contained micrometastases. In 9 tumor‐positive specimens only micrometastases were found. This high incidence of micrometastases has important implications for the diagnostic work‐up, the treatment, and histopathological examination of the N0 neck.

Regional DTI differences in multiple sclerosis patients

Diffusion tensor imaging (DTI) measures have shown to be sensitive to white matter (WM) damage in multiple sclerosis (MS), not only inside focal lesions but also in user-defined regions in the so-called normal-appearing white matter (NAWM). New analysis techniques for DTI measures are now available that allow for hypothesis-free localization of damage. We performed DTI measurements of 30 MS patients selected for low focal lesion loads, and of 31 age-matched healthy controls and analyzed these using tract-based spatial statistics (TBSS). Patients were found to have a lower fractional anisotropy (FA) compared to controls in a number of brain regions, including the fornices, the left corona radiata, the inferior longitudinal fasciculus in both hemispheres, both optic radiations, and parts of the corpus callosum. In the regions of reduced FA, an increase in radial diffusivity and a less pronounced increase of axial diffusivity were found. Neurocognitive assessment showed that patients had normal visuospatial memory performance, just-normal attention, and impaired processing speed; the latter was associated with abnormal FA in the corpus callosum, an area which was relatively devoid of lesions visible on proton density-weighted images in our patients. TBSS can be useful in future studies with other MS patient samples to provide an unbiased localization of damage and generate location-specific hypotheses.

Performance of Immuno–Positron Emission Tomography with Zirconium-89-Labeled Chimeric Monoclonal Antibody U36 in the Detection of Lymph Node Metastases in Head and Neck Cancer Patients

Purpose: Immuno–positron emission tomography (PET), the combination of PET with monoclonal antibodies (mAb), is an attractive option to improve tumor detection and to guide mAb-based therapy. The long-lived positron emitter zirconium-89 (89Zr) has ideal physical characteristics for immuno-PET with intact mAbs but has never been used in a clinical setting. In the present feasibility study, we aimed to evaluate the diagnostic imaging performance of immuno-PET with 89Zr-labeled-chimeric mAb (cmAb) U36 in patients with squamous cell carcinoma of the head and neck (HNSCC), who were at high risk of having neck lymph node metastases. Experimental Design: Twenty HNSCC patients, scheduled to undergo neck dissection with or without resection of the primary tumor, received 75 MBq 89Zr coupled to the anti-CD44v6 cmAb U36 (10 mg). All patients were examined by computed tomography (CT) and/or magnetic resonance imaging (MRI) and immuno-PET before surgery. Six patients also underwent PET with 18F-fluoro-2-deoxy-d-glucose. Immuno-PET scans were acquired up to 144 hours after injection. Diagnostic findings were recorded per neck side (left or right) as well as per lymph node level (six levels per side), and compared with histopathologic outcome. For this purpose, the CT/MRI scores were combined and the best of both scores was used for analysis. Results: Immuno-PET detected all primary tumors (n = 17) as well as lymph node metastases in 18 of 25 positive levels (sensitivity 72%) and in 11 of 15 positive sides (sensitivity 73%). Interpretation of immuno-PET was correct in 112 of 121 operated levels (accuracy 93%) and in 19 of 25 operated sides (accuracy 76%). For CT/MRI, sensitivities of 60% and 73% and accuracies of 90% and 80% were found per level and side, respectively. In the six patients with seven tumor-involved neck levels and sides, immuno-PET and 18F-fluoro-2-deoxy-d-glucose PET gave comparable diagnostic results. Conclusion: In this study, immuno-PET with 89Zr-cmAb U36 performed at least as good as CT/MRI for detection of HNSCC lymph node metastases.

Altered diffusion tensor in multiple sclerosis normal-appearing brain tissue: cortical diffusion changes seem related to clinical deterioration.

To investigate normal‐appearing white (NAWM) and cortical gray (NAGM) matter separately in multiple sclerosis (MS) in vivo using diffusion tensor imaging (DTI).

MR spectroscopic evidence for glial increase but not for neuro-axonal damage in MS normal-appearing white matter

Quantitative single‐voxel, short echo‐time (TE) MR spectroscopy (MRS) was used to determine metabolite concentrations in the cerebral normal‐appearing white matter (NAWM) of 76 patients with multiple sclerosis (MS), and the WM of 25 controls. In NAWM of all MS disease types (primary progressive, relapsing‐remitting, and secondary progressive), the concentration ratio of total N‐acetyl‐aspartate (tNAA)/total creatine (tCr) was decreased compared to controls. Remarkably, this was entirely due to an increase of tCr in MS patients, whereas there was no difference in tNAA. Separate quantification of the two tNAA components yielded no significant difference in NAA (N‐acetyl‐aspartate), while the concentration of NAAG (N‐acetyl‐aspartyl‐glutamate) was slightly—but significantly—elevated in MS patients. Myo‐inositol (Ins) was strongly increased in MS patients, and choline‐containing compounds (Cho) were mildly increased. There were no metabolite differences between disease types, and no correlations with disability scores. The results are supported by measures of spectral quality, which were identical for patients and controls. In conclusion, MS NAWM containing very little perilesional tissue is characterized by increased glial cell numbers (increase of Ins and tCr) without evidence of axonal dysfunction (normal NAA). Further studies should elucidate the mechanism underlying increased NAAG in MS NAWM. Magn Reson Med 53:256–266, 2005.

MR spectroscopic evidence for thalamic and hippocampal, but not cortical, damage in multiple sclerosis.

Gray matter (GM) damage is an important pathophysiological feature in Multiple Sclerosis (MS), and may be related to clinical, including cognitive, deficits. Quantitative single‐voxel 1H‐Magnetic Resonance Spectroscopy (TR/TE 6000/20 ms) was performed in 33 MS patients (11 per disease subtype; mean age 48 years, 16 females) and 10 healthy controls (mean age 43 years, 7 females). No overall spectroscopic changes were found in MS cortex. In MS thalamus, a 9% decrease of N‐acetyl aspartate (NAA; P = 0.005) and a 31% increase of myo‐inositol (Ins; P = 0.002) were found. A 21% Ins increase was observed (P = 0.02) in MS hippocampus. Reduced NAA and increased Ins concentrations are thought to reflect neuro‐axonal damage or loss and gliosis, respectively. Significant correlations between Ins concentrations and total‐brain T2 lesion load were found for MS thalamus (r = 0.65, P < 0.001) and hippocampus (r = 0.57, P = 0.001). MS thalamic and hippocampal Ins concentrations also correlated with each other (r = 0.68; P < 0.001). Cortical Gln correlated with thalamic NAA (r = −0.38; P = 0.03) in MS. Thalamic and hippocampal Ins increases were most prominent in secondary‐progressive (SP) patients (37% and 34%, respectively), whereas the largest thalamic NAA decrease (14%) was found in primary‐progressive (PP) patients. In conclusion, thalamic and hippocampal GM pathology are important features of (progressive) MS. Magn Reson Med, 2006.

Radiation Dosimetry of 89Zr-Labeled Chimeric Monoclonal Antibody U36 as Used for Immuno-PET in Head and Neck Cancer Patients

Immuno-PET is an appealing concept in the detection of tumors and planning of antibody-based therapy. For this purpose, the long-lived positron emitter 89Zr (half-life, 78.4 h) recently became available. The aim of the present first-in-humans 89Zr immuno-PET study was to assess safety, biodistribution, radiation dose, and quantification of the 89Zr-labeled chimeric monoclonal antibody (cmAb) U36 in patients with head and neck squamous cell carcinoma (HNSCC). In addition, the performance of immuno-PET for detecting lymph node metastases was evaluated, as described previously. Methods: Twenty HNSCC patients, scheduled to undergo surgical tumor resection, received 75 MBq of 89Zr-cmAb U36 (10 mg). Immuno-PET scans were acquired at 1, 24, 72, or 144 h after injection. The biodistribution of the radioimmunoconjugate was evaluated by ex vivo radioactivity measurement in blood and in biopsies from the surgical specimen obtained at 168 h after injection. Uptake levels and residence times in blood, tumors, and organs of interest were derived from quantitative immuno-PET studies, and absorbed doses were calculated using OLINDA/EXM 1.0. The red marrow dose was calculated using the residence time for blood. Results: 89Zr-cmAb U36 was well tolerated by all subjects. PET quantification of blood-pool activity in the left ventricle of the heart showed a good agreement with sampled blood activity (difference equals 0.2% ± 16.9% [mean ± SD]) except for heavy-weight patients (>100 kg). A good agreement was also found for the assessment of mAb uptake in primary tumors (mean deviation, −8.4% ± 34.5%). The mean absorbed red marrow dose was 0.07 ± 0.02 mSv/MBq and 0.09 ± 0.01 mSv/MBq in men and women, respectively. The normal organ with the highest absorbed dose was the liver (mean dose, 1.25 ± 0.27 mSv/MBq in men and 1.35 ± 0.21 mSv/MBq in women), thereafter followed by kidneys, thyroid, lungs, and spleen. The mean effective dose was 0.53 ± 0.03 mSv/MBq in men and 0.66 ± 0.03 mSv/MBq in women. Measured excretion via the urinary tract was less than 3% during the first 72 h. Conclusion: 89Zr immuno-PET can be safely used to quantitatively assess biodistribution, uptake, organ residence times, and radiation dose, justifying its further clinical exploitation in the detection of tumors and planning of mAb-based therapy.

In vivo detection of myelin proteins in cervical lymph nodes of MS patients using ultrasound-guided fine-needle aspiration cytology

Cervical lymph nodes (CLN) have been described to be the first lymphoid draining site of the brain. In this study we used ultrasound guided fine needle aspiration cytology (USgFNAC) to obtain cells, in vivo, from non-enlarged CLN of multiple sclerosis (MS) patients and HCs (HC), and investigated whether myelin proteins could be detected. Macrophages containing myelin basic protein (MBP) and proteolipid protein (PLP) were found in CLN of all MS patients, whereas these could only be detected in a minority of HC. This novel approach allows investigation of the first draining site of the brain for in vivo analysis of the immune regulation of MS.

Structural and Functional Hippocampal Changes in Multiple Sclerosis Patients with Intact Memory Function

PURPOSE To investigate changes in hippocampal functional connectivity and structural measures of hippocampal damage in multiple sclerosis (MS) patients with intact spatial memory, a cognitive domain frequently affected in progressive MS. MATERIALS AND METHODS The study protocol was approved by the institutional ethics review board; all subjects gave written informed consent prior to participation. Twenty-five MS patients with intact spatial memory function were compared with 30 age- and sex-matched controls. Hippocampal volume differences, based on manually drawn masks, were evaluated by using the Student t test. Additionally, focal hippocampal lesions and mean diffusivity were obtained as descriptive measures of structural hippocampal damage. Multiple regression analyses of the resting-state functional magnetic resonance (MR) imaging data were performed for each subject by using hippocampal time series. Between-group analyses were conducted with a mixed-effects model, corrected for multiple comparisons by a cluster defining threshold level of z = 2 and a corrected cluster size significance level of P < .05. RESULTS Right hippocampal volume was significantly lower in MS patients as compared with controls (P < .01). Left hippocampal volume was also lower in MS patients compared with controls, but not significantly so (P = .09). Resting-state functional connectivity between the hippocampus and its anatomic input or target areas, including the anterior cingulate gyrus, thalamus, and prefrontal cortex, were significantly decreased in MS patients. Decreased hippocampal functional connectivity was more pronounced in a subgroup of MS patients with hippocampal atrophy, although subtle decreases of functional connectivity were also found in patients with normal hippocampal volume. CONCLUSION In MS patients, substantial abnormalities of hippocampal functional connectivity are already present before spatial memory function is impaired, especially in those patients with more pronounced hippocampal atrophy. Longitudinal studies should now assess whether these functional connectivity and structural changes may precede memory impairment in MS.

Lymph node staging in patients with clinically negative neck examinations by ultrasound and ultrasound-guided aspiration cytology

To assess the usefulness of ultrasound and ultrasound-guided fine-needle aspiration cytology in detecting occult cervical lymph node metastases, 107 patients with squamous cell carcinoma of the head and neck, who underwent 132 elective neck dissections, had preoperative ultrasound examination. During the assessment of the last 54 patients, who underwent 70 elective neck dissections, ultrasound-guided aspiration cytology was available. Although ultrasound was able to detect lymph node metastases in the majority of patients, the accuracy of this technique never exceeded 70% (93 of 132 procedures). With ultrasound-guided aspiration cytology, accuracy was 89% (62 of 70 procedures). This latter technique seems to be the modality of choice for the assessment of the clinically negative neck. Its use obviates the need for elective neck dissection, done because of the high risk of occult metastasis.