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Biomedical subjects

M Oudkerk

Publications and source records attributed to M Oudkerk.

At least 109 records · Page 6Linked to original sources
PubMed1997

Hepatic lesions: detection with ferumoxide-enhanced T1-weighted MR imaging.

PURPOSE: To compare the use of ferumoxide-enhanced T1-weighted gradient-echo (GRE) MR imaging with that of spiral computed tomography during arterial portography (CTAP) and T2-weighted Turbo spin-echo (SE) MR imaging in detection of lesions and of segmental involvement in patients with liver metastases. MATERIALS AND METHODS: Twenty-two candidates for metastasectomy of the liver underwent spiral CTAP, ferumoxide-enhanced GRE MR imaging, and T2-weighted Turbo SE MR imaging. A total of 176 liver segments were evaluated (57 with and 119 without metastases). The reference standard was laparoscopic sonographic findings. Diagnostic performance of the imaging modalities was assessed for lesion detection and determination of segmental involvement. RESULTS: The sensitivity for lesion detection with spiral CTAP, ferumoxide-enhanced MR imaging, and T2-weighted MR imaging was 0.96, 0.83, and 0.71, respectively; for segmental analysis, the sensitivity was 0.96, 0.84, and 0.75, respectively, and the specificity was 0.80, 0.99, and 0.92, respectively. All comparisons between sensitivities and specificities were statistically significant (P < .05). CONCLUSION: Ferumoxide-enhanced T1-weighted GRE MR imaging is superior to T2-weighted SE MR imaging for preoperative detection of lesions and segmental involvement in patients with liver metastases.

Adult↗
PubMed1996

1H MR spectroscopy detection of lipids and lactate in metastatic brain tumors.

1H MR spectroscopy was used to correlate the metabolite signals in 66 untreated metastatic brain tumors with the results of Gd-DTPA enhanced MRI. Cubic volumes containing brain metastases of lung cancer (n = 17), mammary carcinoma (n = 24), melanoma (n = 12) and those originating from other tumors (n = 13) were examined using the double spin echo technique with CHESS pulses for water suppression and TE = 135 ms. Apart from trends toward reduced signals of choline-containing compounds (Cho) and reduced post-Gd MRI contrast in lung cancer compared with the other pathology groups, the four tumor groups had similar MRI and MRS characteristics. Metastases without lipid or lactate (Lact) signal in the 1H MR spectra were comparatively small in size with homogeneous post-Gd MRI enhancement (33 +/- 5%, means +/- SEM; n = 24) and elevated Cho signals compared with normal contralateral brain tissue (70 +/- 5% of contralateral N-acetyl aspartate signal; p < 0.001). The other metastases showed either unambiguous lipid signals (n = 30) or MRS detectable Lact (n = 12) and were heterogeneous on MRI with divergent signals of Gd-enhancement (49 +/- 5% vs 14 +/- 8%, p < 0.001) and Cho (88 +/- 10 vs 47 +/- 8% of contralateral NAA; p = 0.02). Those with Lact were significantly larger compared with both other groups (p < 0.02, both). It is concluded that brain metastases can be categorized into early stage (Cho), intermediate stage (lipid, higher Cho) and late stage metastases (Lact, lower Cho).

Brain Neoplasms↗
PubMed1996

Biopsy of nonpalpable cervical lymph nodes: selection criteria for ultrasound-guided biopsy in patients with head and neck squamous cell carcinoma.

This article is designed to find an appropriate policy to select nonpalpable cervical lymph nodes in head and neck squamous cell carcinoma patients for ultrasound-guided aspiration biopsy (USB). According to the literature, generally used selection criteria are width of nodes > 10 mm, length-to-width ratio > 2 and absent echo-rich hilum. In 562 nonpalpable nodes of 355 patients (mean age 60 y, range 20-92 y) with head and neck squamous cell carcinoma, a USB procedure was carried out. Nodes were classified according to dimensions and to echo pattern. Representative cytology was obtained in 489 nodes; 112 were classified as malignant. Of the 412 nodes with a width < or = 10 mm, 79 were malignant. Width is the strongest predictor for malignancy and, if corrected for width, the length-to-width ratio is of no influence. Of the 142 nodes with an echo-poor centre, or an inhomogeneous pattern, 46% were malignant, compared to 13% of 342 nodes with an echo-rich centre. It is concluded that selection of lymph nodes of the neck of patients with squamous cell carcinoma of the head and neck should be based on width and echo pattern. We advise subjecting nodes with an echo-rich centre or homogeneous pattern and a width > or = 4 mm to USB, and also subjecting nodes with an echo-poor centre or inhomogeneous pattern with a width > or = 3 mm to USB.

Adult↗
PubMed1996

Detection of liver metastases from colorectal carcinoma: is there a place for routine computed tomography arteriography?

BACKGROUND: A prospective evaluation of the liver by preoperative ultrasonography, conventional computed tomography (CT), and continuous CT angiography (CCTA) was performed in 60 patients with primary or secondary colorectal carcinoma. METHODS: The standards of reference were palpation of the liver and intraoperative ultrasonography. The imaging techniques were assessed independently of each other. RESULTS: In 37 patients 105 liver metastases were identified; 23 patients had no metastases. CCTA and a high sensitivity of 94% (99 lesions identified) in contrast to ultrasonography (48%) and conventional CT (52%). The superiority of CCTA was also manifest in lesions less than 1 cm in diameter. However, the high sensitivity was accompanied by a high false-positive rate, particularly because of variations in the perfusion of normal liver parenchyma. Overall, CCTA had the highest accuracy (74%) compared with ultrasonography and CT (both 57%). The data indicate that preoperative ultrasonography and conventional CT have low sensitivity in the detection of liver metastases. CONCLUSIONS: Although CCTA seems to be superior to other preoperative imaging techniques, the too low specificity will hamper its routine application in patients with hepatic metastases from colorectal carcinoma.

Angiography↗
PubMed1995

[Good results in periodic screening in women with increased risk of breast cancer; retrospective study].

OBJECTIVE: To determine the efficiency of surveillance among women with a high risk of breast cancer by semiannual breast examination and annual mammography. SETTING: 'Dr. Daniel den Hoed' Cancer Centre, Rotterdam, the Netherlands. DESIGN: Retrospective study. METHOD: In 1994 breast cancer was diagnosed in 92 patients: in 19 patients during surveillance (SU), in 48 referred because of symptoms (SY) and in 25 during the national screening programme (SC). The contributions of physical examination, mammography, ultrasound and fine needle aspiration cytology to the diagnosis were evaluated and the tumour stages in the 3 groups were compared. RESULTS: The mean age was 53 years in the SU group, 51 years in the SY group and 64 years in the SC group. Breast cancer was detected by mammography only in 6%, 40% and 42% in the SY, SC and SU groups, respectively. 42% of patients had a family history of breast cancer in the SU group. Mammography failed to reveal malignancy in 25% of patients in the SU and SY groups combined. In women in the SU group 53% of breast cancers were: carcinoma in situ (Tis) or minimal invasive carcinoma (< 0.5 cm diameter; T1a). In patients with a family history of breast cancer 75% (6/8) were diagnosed in stages Tis or T1a, by surveillance. In the SY group 4% were Tis or T1a and 40% N1 + 2, in the SC group 8% and 20% respectively. 15.7% of the SU group had axillary lymph node metastases (N1) but only one of the 8 patients with a family history of breast cancer. CONCLUSIONS: Surveillance by palpation and mammography in women with a high risk of breast cancer is useful, because it detects this disease frequently at an early stage, when the prognosis is still good.

Adult↗
PubMed1995

31P magnetic resonance spectroscopy as predictor of clinical response in human extremity sarcomas treated by single dose TNF-alpha + melphalan isolated limb perfusion.

Irresectable extremity sarcomas are large (grade II/III) tumors requiring amputation of the limb for local control. Limb salvage can be achieved by isolated limb perfusion (ILP) with tumor necrosis factor alpha (TNF-alpha), interferon-gamma and melphalan. To obtain insight into the effects of single dose ILP on extremity tumors, phosphate metabolism was monitored by 31P magnetic resonance spectroscopy (MRS) using the chemical shift imaging (CSI) technique. 2D CSI was used in combination with a slice select gradient in the third dimension to obtain true 3D localization. Spectral maps obtained prior to ILP revealed reductions in phosphocreatine (PCr) level and increases in phosphomonoester (PME) and phosphodiester (PDE) in tumor compared with muscle tissue. ILP treated tumors showed highly divergent changes in Pi while PME decreased in all cases (n = 11). Tumor volume, unchanged on day 8 after ILP, was decreased by 58 +/- 29% (mean +/- SD) at 2 months. Linear regression analysis revealed correlation between the changes in tumor metabolites measured on day 8, with percent volume decrease (Pi: r = -0.88, p < 0.001) and percent necrosis at resection (PME: r = -0.79, p -0.01). Correlation between pretreatment spectra and effectiveness of ILP treatment was not found. It is concluded that a single ILP with TNF-alpha + melphalan induced changes in tumor metabolite levels (measured on day 8) that reflect treatment efficacy. 31P MRS can thus provide information facilitating the decision as to when to remove tumor (residue) and, in the case where tumor remains inoperable, whether or not to apply additional therapy.

Adult↗
PubMed1995

Non-T1-weighted 31P chemical shift imaging of the human liver.

A 31P chemical shift imaging (CSI) protocol was developed for human liver studies. It is shown that at the commonly used repetition time (TR) of 1 s T1-weighting reduces the integrated intensities of liver phosphate metabolite signals by 18 +/- 15% (inorganic phosphate, Pi) to 46 +/- 10% (phosphodiester, PDE), that is for an RF pulse angle of 60 degrees (weighted average) in liver. The loss in signal-to-noise ratio (S/N) at TR = 20 s, sufficient to eliminate spectral distortions caused by saturation, compared with TR = 1 s (47-65%) can be overcome by using one-dimensional (1D)-phase encoding with a small number of phase-encode steps. The liver spectra obtained by 1D-CSI with 4-step phase-encoding (spatial resolution 10 cm) have the highest S/N and, after multiplication of the PDE signal by a factor of 1.4, closely reflect the liver metabolite levels. It is concluded that clinical 31P MR studies of liver function can be performed without T1-weighting and that the current practice to compromise the MRS quantification of lever metabolites with uncertainties caused by (differential changes in) T1-weighting is not warranted.

Humans↗
PubMed1995

Safety and efficacy of dotarem (Gd-DOTA) versus magnevist (Gd-DTPA) in magnetic resonance imaging of the central nervous system.

RATIONALE AND OBJECTIVES: Gd-DTPA is a well-characterized, safe contrast agent frequently used in magnetic resonance imaging (MRI) of the central nervous system. The purpose of this double-blind, comparative MRI study of brain, spine, trunk, and limbs was to evaluate the safety and efficacy of Gd-DOTA versus Gd-DTPA in a large number of patients (n = 1038). METHODS: T1-weighted MRI was performed before contrast and after the administration of Gd-DOTA or Gd-DTPA (0.1 mmol/kg). The MR images were scored for image quality, and the diagnostic efficacy also was assessed. Patients were questioned 1 hour after injection, and adverse reactions were recorded. RESULTS: Image quality of the T1-weighted MR images without contrast was good or excellent in 89.7% and 91.7% of the Gd-DOTA and Gd-DTPA groups, respectively (P > 0.2). After contrast, 85.8% (Gd-DOTA) and 88.2% (Gd-DTPA) of the T1-weighted MR images were of good to excellent image quality (P > 0.2), significantly less than before contrast (P < 0.001, both groups). In 82.3% of the Gd-DOTA group and 83.5% of the Gd-DTPA group (P > 0.2), the information obtained was more accurate with the administration of contrast agents. In 82.4% (Gd-DTPA) and 81.9% (Gd-DOTA) of patients, confirmation was obtained of diagnosis without contrast, whereas in 17.0% and 17.3% of patients, therapy was modified as a result of the use of contrast (P > 0.2, both groups). The MRI investigation was reported as abnormal in 58.3% (Gd-DOTA) and 59.6% of patients (Gd-DTPA), indicating a similar prevalence of disease in each group. Patients responded that 97.8% (Gd-DOTA) and 98.5% (Gd-DTPA) of the investigations went well and adverse reactions, none of them serious, were encountered in 0.97% of Gd-DOTA and 0.77% of Gd-DTPA groups (P > 0.2, both groups). CONCLUSION: This double-blind, randomized, clinical trial comparing Gd-DTPA and Gd-DOTA revealed no serious adverse reactions, whereas minor adverse reactions were encountered in fewer than 1% of patients. Gd-DOTA is as safe a contrast agent as Gd-DTPA and has similar diagnostic efficacy.

Adult↗
PubMed1995

Hydrogen magnetic resonance spectroscopy follow-up after radiation therapy of human brain cancer. Unexpected inverse correlation between the changes in tumor choline level and post-gadolinium magnetic resonance imaging contrast.

RATIONALE AND OBJECTIVES: The anatomic and metabolic changes in human brain tumors treated by radiation therapy were compared using gadolinium-enhanced magnetic resonance imaging and hydrogen (1H) magnetic resonance spectroscopy. The study was intended to assess the potential of 1H magnetic resonance spectroscopy in monitoring response to therapy. METHODS: Thirteen cases of brain cancer treated by radiation therapy were examined by 1H magnetic resonance spectroscopy and gadolinium-enhanced T1-weighted magnetic resonance imaging and reexamined at 2-month intervals. RESULTS: Follow-up after radiation therapy showed changes in post-gadolinium magnetic resonance imaging contrast that are inversely correlated with the changes in choline level (r = -0.69, P < 0.00001) and in tumor volume (r = -0.35, P < 0.05). CONCLUSIONS: The choline loss in tumors gaining post-gadolinium magnetic resonance imaging contrast after therapy is unexpected in view of previously reported correlation between the two in untreated metastatic brain tumors. Indicated is the use of 1H magnetic resonance spectroscopy to discriminate enhancing brain tumors with a high content of vital tumor cells (high choline) from tumors, combining decreased cell density with increased interstitial space (low choline).

Aspartic Acid↗
PubMed1994

Correlation between choline level and Gd-DTPA enhancement in patients with brain metastases of mammary carcinoma.

Single voxel 1H double spin-echo MR spectroscopy was used to examine 15 cases of brain metastasis of mammary carcinoma (18 lesions) in relation to Gd-DTPA enhanced MR imaging. For lesions larger than 50% of MRS voxel size, there was significant correlation between Gd-DTPA-enhanced MRI signal and MRS-detected signal of choline (Cho) containing compounds (r = 0.86, P < 0.01; n = 8). The observed loss of correlation when including the smaller lesions was overcome by correcting for partial volume effects (r = 0.69, P < 0.002; n = 18). Metastasis spectra showed increased Cho compared with control spectra, except for those lesions showing detectable lactate (Lact) signal. The detection of Lact in four of the larger lesions coincided with comparatively low levels of creatine (Cr) and Cho and heterogeneous Gd-DTPA enhancement (Cr) and Cho and heterogeneous Gd-DTPA enhancement (ring-enhancement). It was concluded that in brain metastases of mammary carcinoma Lact represents a product of ischemia preceding/during tissue decay resulting in central necrosis, rather than tumor specific metabolism resulting in increased glycolysis.

Adult↗
PubMed1994

Leucocytoclastic vasculitis as presenting feature of primary Sjögren's syndrome.

Described are two patients whose primary Sjögren's syndrome presented as leucocytoclastic vasculitis of the skin. One patient initially admitted complaints of dryness of the eyes and the mouth after direct questioning, and serologic testing revealed the presence of Ro/SS-A and La/SS-B antibodies. In the other patient the presence of antinuclear antibodies and rheumatoid factors in serum were the only suggestions of the presence of primary Sjögren's syndrome. Primary Sjögren's syndrome should be considered in patients presenting with leucocytoclastic vasculitis.

Adult↗
PubMed1994

Solid breast neoplasms: differential diagnosis with pulsed Doppler ultrasound.

In this prospective study, duplex Doppler ultrasound was used in 95 consecutive patients with solid breast masses to evaluate the presence of neovascular flow. A positive Doppler signal, i.e., a Doppler shift frequency of more than 1 kHz using a 5 MHz insonating frequency, was found in 34 of 57 patients with a carcinoma, and also in three patients with a benign condition. These results indicate that negative findings with pulsed Doppler ultrasound cannot be used to exclude malignancy. However, a frequency shift of more than 1 kHz indicates a high probability for malignancy. In our study a high frequency shift was not related to tumor size. We also evaluated the correlation between a high frequency shift and axillary nodal metastasis. According to our results there is a very low chance of axillary metastasis when no high frequency shifts are found.

Adult↗
PubMed1994

Renal masses: value of duplex Doppler ultrasound in the differential diagnosis.

In a prospective study, 84 nonanechoic renal masses were examined with duplex Doppler ultrasound with a 3.5 mHz. transducer. This study included malignant lesions in 49 cases (30 renal carcinomas, 9 metastases, 8 lymphomas and 2 sarcomas) and benign lesions in 35 (18 complicated cysts, 6 inflammatory processes, 5 columns of Bertin, 3 angiomyolipomas and 3 hematomas). We analyzed whether duplex Doppler ultrasound can have a role in the differential diagnoses of these solid renal masses. Renal carcinomas demonstrated Doppler shifts of 2.5 kHz. or more in 23 cases (77%). These masses had significantly higher Doppler shifts than all of the other malignant masses (p < 0.001). Among the benign lesions the Doppler shifts were less than 2.5 kHz. in 33 cases (84%). The 2 masses with a Doppler shift of more than 2.5 kHz. in this group were inflammatory lesions. Detection of a Doppler shift of 2.5 or greater in a renal mass supports suspicion of a renal cell carcinoma, although an inflammatory process may also produce such a high Doppler shift. Doppler shifts of less than 2.5 kHz. in solid renal masses support the diagnoses of a benign lesion and a malignant lesion other than renal cell carcinoma.

Adult↗
PubMed1993

Cost-effectiveness analysis of various strategies in the diagnostic management of pulmonary embolism.

BACKGROUND: Since the clinical diagnosis of pulmonary embolism is unreliable, various objective diagnostic methods (or combinations thereof) are advocated. Pulmonary angiography is the accepted reference method but is considered less suitable for initial screening due to its invasive nature. Therefore, at least nine different diagnostic management strategies employing invasive and noninvasive diagnostic tests are used in clinical practice. We assessed the cost-effectiveness of these strategies to help identify the optimal approach. METHODS: Based on assumptions derived from published data, we calculated mortality, morbidity, adequacy for the indication of anticoagulant therapy, and associated diagnostic and therapeutic costs using a decision analytic model. Additionally, a cost-effectiveness analysis was performed using incremental costs per additional life saved. RESULTS: The analysis identified three separate categories of diagnostic management strategies: (1) Treatment of all patients (or of those with an abnormal perfusion scan) results in the lowest mortality and morbidity rates but the highest costs due to inappropriate treatment of 55% to 70% of patients. (2) Pulmonary angiography strategies with or without prior perfusion-ventilation lung scintigraphy and ultrasonography of the legs have comparable low mortality and morbidity rates, costs savings of approximately 40%, and inappropriate treatment in fewer than 5% of patients. (3) Use of perfusion-ventilation scintigraphy with or without ultrasonography results in unacceptably high mortality rates. CONCLUSIONS: At present, the optimal diagnostic management strategy should include pulmonary angiography. Use of perfusion-ventilation lung scintigraphy and ultrasonography results in a 40% to 50% reduction in the number of patients requiring pulmonary angiography and is cost-effective.

Angiography↗
PubMed1993

[Consensus diagnosis pulmonary embolism].

Pulmonary embolism is a frequent occurrence and requires adequate diagnosis and treatment to avoid unnecessary mortality and complications. However, until recently, the optimal diagnostic management was not determined. This prompted the organisation of a consensus meeting. The advised diagnostic strategy was derived from available data in the literature, a cost-effectiveness analysis, and the discussions which took place at the meeting. The preferred diagnostic strategy consists of a combination of perfusion-ventilation lung scintigraphy, ultrasonography of the legs, and finally pulmonary angiography. Perfusion scintigraphy is performed first. If a normal perfusion is seen further anticoagulant therapy may be withheld. Ventilation scintigraphy is performed if a segmental or larger perfusion defect is found. If a normal ventilation scan is obtained (mismatch) the diagnosis of pulmonary embolism is sufficiently certain to warrant institution of long-term anticoagulant therapy. In all other lung scan findings (non-conclusive or non-diagnostic) the meeting advised to perform ultrasonography of the legs. If deep venous thrombosis is detected the patient requires long-term anticoagulant therapy. If a normal ultrasound result is found, pulmonary angiography is required as the final test in the diagnostic strategy.

Cost-Benefit Analysis↗