C. Stroszczynski

Concentration and oxygen saturation of haemoglobin of 50 breast tumours determined by time-domain optical mammography

Using a dual-wavelength (670 nm, 785 nm) time-domain scanning instrument we have recorded optical mammograms of 93 patients suspected of having breast cancer which was subsequently assessed histologically. Among 65 histologically confirmed carcinomas, 54 were detectable in at least one of two optical mammograms recorded of each tumour-bearing breast in craniocaudal and mediolateral projection. Optical mammograms were based on photon counts in selected time windows of measured distributions of times of flight of photons. Optical properties of 50 carcinomas investigated at both wavelengths were derived by modelling the breast as partially homogeneous infinite slab with an embedded spherical inhomogeneity representing the tumour and by calculating the diffraction of photon density waves. In selected cases, additional information about the location of the tumour along the compression direction was used that was obtained from scans at selected offsets between source and detector optical fibres. A correlation plot of haemoglobin concentration and blood oxygen saturation of tumours and healthy tissue shows good separation between both kinds of tissue. The majority of carcinomas exhibited increased total haemoglobin concentration compared to healthy tissue.

Time-domain scanning optical mammography: I. Recording and assessment of mammograms of 154 patients

Using a triple wavelength (670 nm, 785 nm, 843/884 nm) scanning laser-pulse mammograph we recorded craniocaudal and mediolateral projection optical mammograms of 154 patients, suspected of having breast cancer. From distributions of times of flight of photons recorded at typically 1000-2000 scan positions, optical mammograms were derived displaying (inverse) photon counts in selected time windows, absorption and reduced scattering coefficients or total haemoglobin concentration and blood oxygen saturation. Optical mammograms were analysed by comparing them with x-ray and MR mammograms, including results of histopathology, attributing a subjective visibility score to each tumour assessed. Out of 102 histologically confirmed tumours, 72 tumours were detected retrospectively in both optical projection mammograms, in addition 20 cases in one projection only, whereas 10 tumours were not detectable in any projection. Tumour contrast and contrast-to-noise ratios of mammograms of the same breast, but derived from measured DTOFs by various methods were quantitatively compared. On average, inverse photon counts in selected time windows, including total photon counts, provide highest tumour contrast and contrast-to-noise ratios. Based on the results of the present study we developed a multi-wavelength, multi-projection scanning time-domain optical mammograph with improved spectral and spatial (angular) sampling, that allows us to record entire mammograms simultaneously at various offsets between the transmitting fibre and receiving fibre bundle and provides first results for illustration.

Restaging of Locally Advanced Carcinoma of the Rectum with MR Imaging after Preoperative Radio-Chemotherapy plus Regional Hyperthermia

Background: The restaging accuracy of MR imaging in advanced primary rectal carcinoma after preoperative radiochemotherapy and regional hyperthermia was evaluated and compared with the histopathologically verified degree of tumor remission after a course of radio-chemo-thermotherapy. Patients and Methods: 35 patients with primary rectal carcinoma (uT3/uT4) underwent MRI using a surface coil 4–6 weeks after radiochemotherapy (n = 35), regional hyperthermia (n = 23), and before curative surgery. We defined as gold standard for the remission status the comparison of pretherapeutic endosonography with the histopathology of the resected specimen. Results: T category was correctly restaged after preoperative treatment in only 19 (54%) of 35 patients. Nine of 20 responders were overstaged and seven of 15 non-responders were understaged. Concurrently, the N category was correctly restaged in 19 (54%) of 35 patients (twelve responders and seven non-responders). Overstaging occurred in four responders and two non-responders, understaging occurred in four responders and six non-responders. Conclusions: MRI proved independent of the response status as not suitable to restage locally advanced rectal carcinoma after preoperative radiochemotherapy despite optimized imaging technique and spatial resolution. Basically, imaging the morphology of a tumor cannot clearly differentiate between vital and devitalized tissue after a treatment. Functional imaging such as PET (positron emission tomography) appears more feasible for restaging after radio-chemo-thermotherapy.Hintergrund: Die Genauigkeit der Stadienbestimmung mittels MR-Bildgebung wurde bei primär fortgeschrittenen Rektumkarzinomen nach präoperativer Radiochemotherapie und regionaler Hyperthermie geprüft und mit der histopathologisch ermittelten Tumorremission nach präoperativer Behandlung verglichen. Patienten und Methode: 35 Patienten mit primären Rektumkarzinomen (uT3/uT4) wurden MR-tomographisch mittels Oberflächenspule 4–6 Wochen nach Radiochemotherapie (n = 35) plus Hyperthermie (n = 23) vor der kurativen Resektion untersucht. Als Goldstandard für die Remission wurde der Vergleich von prätherapeutischer Endosonographie mit dem histopathologischen Befund des Resektats definiert. Ergebnisse: Das T-Studium nach präoperativer Behandlung wurde nur bei 19 von 35 Patienten (54%) korrekt wiedergegeben, bei neun von 20 Respondern überbenimmt und bei sieben von 15 Nonrespondern unterschätzt. Daneben wurde auch cie N-Kategorie bei 19 von 35 Patienten (54%) korrekt bestimmt (bei zwölf Respondern und sieben Nonrespondern). Eine Überschätzung trat bei vier Respondern und zwei Nonrespondern auf, eine Unterschätzung bei vier Respondern und sechs Nonrespondern. Schlussfolgerungen: Die MR-Bildgebung erwies sich trotz optimierter Aufnahmetechnik mit erhöhter räumlicher Auflösung und unabhängig vom Remissionsstatus als ungeeignet, das Stadium lokal fortgeschrittener Rektumkarzinome nach präoperativer Radiochemotherapie exakt zu ermitteln. Grundsätzlich ist die Darstellung der Morphologie eines Tumors nicht geeignet, zwischen vitalem und devitalisiertem Tumorgewebe nach Vorbehandlung zu differenzieren. Funktionelle Verfahren (z. B. die Positronenemissionstomographie) könnten für die Verlaufskontrolle nach Radiochemothermotherapie geeigneter sein.

Scanning time-domain optical mammography : Detection and characterization of breast tumors in vivo

Optical mammography is one of several new techniques for breast cancer detection and characterization presently under development for clinical use that provide information other than morphologic, in particular on the biochemical and metabolic state of normal and diseased tissue. In breast tissue, scattering of red to near infrared (NIR) light dominates absorption and NIR light may penetrate several centimeters through the breast. Optical mammography avoids the use of ionizing radiation and offers the power of diffuse optical spectroscopy. However, because of strong light scattering, spatial resolution of optical mammography is generally low. The paper reviews the results of a clinical study on scanning time-domain optical mammography comprising 154 patients carrying a total of 102 carcinomas validated by histology. Ninety two of these tumors were detected in optical mammograms retrospectively and for 87 of the detected tumors optical properties and tissue parameters were derived. In addition developments on instrumentation and data analysis are covered and possible improvements of optical mammography are briefly discussed.

Osteoid Osteoma: Experience with Laser- and Radiofrequency-Induced Ablation

The purpose of this study was to analyze the clinical outcome of osteoid osteoma treated by thermal ablation after drill opening. A total of 17 patients and 20 procedures were included. All patients had typical clinical features (age, pain) and a typical radiograph showing a nidus. In 5 cases, additional histological specimens were acquired. After drill opening of the osteoid osteoma nidus, 12 thermal ablations were induced by laser interstitial thermal therapy (LITT) (9F Power-Laser-Set; Somatex, Germany) and 8 ablations by radiofrequency ablation (RFA) (RITA; StarBurst, USA). Initial clinical success with pain relief has been achieved in all patients after the first ablation. Three patients had an osteoid osteoma recurrence after 3, 9, and 10 months and were successfully re-treated by thermal ablation. No major complication and one minor complication (sensible defect) were recorded. Thermal ablation is a safe and minimally invasive therapy option for osteoid osteoma. Although the groups are too small for a comparative analysis, we determined no difference between laser- and radiofrequency-induced ablation in clinical outcome after ablation.

Minimum intensity projections of the biliary system using 16-channel multidetector computed tomography in patients with biliary obstruction: comparison with MRCP

The objective was the evaluation of minimum intensity projections (MinIP) of 16-channel multidetector computed tomography (MDCT) data for the visualization of biliary ducts with magnetic resonance cholangiopancreatography (MRCP) as reference method. Twenty-five patients with biliary obstruction who received MDCT of the abdomen and MRCP without subsequent interventions were analysed. Coronal and axial MinIP were reconstructed from the MDCT-data. The evaluation of image quality and the quantitative comparison to MRCP was performed by two observers in consensus. The additional diagnostic value of MinIP compared with conventionally visualised MDCT was assessed by three independent observers. With MRCP as the reference method, MinIP was superior to conventional MDCT concerning the visualization of the extent of bile duct dilatation (r, 1.000 vs 0.699) and the correlation of diameter measurement (r, 0.979 vs 0.942). Subsidiary to conventional MDCT, MinIP revealed an improvement of visualization of the biliary system in 73% of cases. Concerning the additional diagnostic value, MinIP allowed for a better definition of the obstruction site in 13% of patients, and in one patient a change of diagnosis was observed. Thus, MinIP can improve the diagnostic assessment of biliary obstructions in MDCT imaging.

Wavelet versus JPEG (Joint Photographic Expert Group) and fractal compression. Impact on the detection of low-contrast details in computed radiographs.

RATIONALE AND OBJECTIVES The aim of this study was to evaluate different lossy image compression algorithms in direct comparison. METHODS Computed radiographs were reviewed after compression with Wavelet, Fractal, and Joint Photographic Expert Group (JPEG) algorithms. For receiver operating characteristic (ROC) analysis, 54 thoracic computed radiographs (31 showing pulmonary nodules) were compressed with a ratio of 1:60. Five images of a test-phantom were coded at 1:13. All images were reviewed on a PC. Uncompressed images were reviewed at a PC and at a radiologic workstation (with image processing). RESULTS For thorax images, decrease of diagnostic accuracy was significant with Wavelets. Fractal performed worse than Wavelets. No ROC curve was observed for JPEG due to poor image quality. No diagnostic loss was noted comparing PC and Workstation review. For low-contrast details of the phantom, results of Wavelet compression were equal to uncompressed images. Fewer true positives and increased true negatives were noted with Wavelets though. Wavelets were superior to JPEG, and JPEG images were superior to Fractal. Workstation review was superior to PC review. CONCLUSIONS Only Wavelets provided accurate review of low-contrast details at a compression of 1:13. Frequency filtering of Wavelets affects contrast even at a low compression ratio. JPEG performed better than Fractal at low and worse at high compression ratio.

Use of Semiflexible Applicators for Radiofrequency Ablation of Liver Tumors

PurposeTo evaluate the feasibility and potential advantages of the radiofrequency ablation of liver tumors using new MRI-compatible semiflexible applicators in a closed-bore high-field MRI scanner.MethodsWe treated 8 patients with 12 malignant liver tumors of different origin (5 colorectal carcinoma, 2 cholangiocellular carcinoma, 1 breast cancer) under MRI guidance. Radiofrequency ablation (RFA) was performed using 5 cm Rita Starburst Semi-Flex applicators (Rita Medical Systems, Milwaukee, WI, USA) which are suitable for MR- and CT-guided interventions and a 150 W RF generator. All interventions were performed in a closed-bore 1.5 T high-field MRI scanner for MRI-guided RFA using fast T1-weighted gradient echo sequences and T2-weighted ultra-turbo spin echo sequences. Control and follow-up MRI examinations were performed on the next day, at 6 weeks, and every 3 months after RFA. Control MRI were performed as double-contrast MRI examinations (enhancement with iron oxide and gadopentetate dimeglumine). All interventions were performed with the patient under local anesthesia and analgo-sedation.ResultsThe mean diameter of the treated hepatic tumors was 2.4 cm (±0.6 cm, range 1.0–3.2 cm). The mean diameter of induced necrosis was 3.1 cm (±0.4 cm). We achieved complete ablation in all patients. Follow-up examinations over a duration of 7 months (±1.3 months, range 4–9 month) showed a local control rate of 100% in this group of patients. All interventions were performed without major complications; only 2 subcapsular hematomas were documented.ConclusionRFA of liver tumors using semiflexible applicators in closed-bore 1.5 T scanner systems is feasible. These applicators might simplify the RFA of liver tumors under MRI control. The stiff distal part of the applicator facilitates its repositioning.

The use of FDG-PET and CT for the staging of adrenocortical carcinoma in children

A 13-year-old boy was found to have a huge right adrenal tumour as an incidental finding during US of the kidneys for a different reason. He had elevated levels of cortisol, dihydroandrostendion and neuronespecific enolase. MRI, CT, angiography and bone scintigraphy showed an adrenal tumour with a solitary liver metastasis, representing stage IV disease. The primary tumour and liver metastasis were resected, and the histological diagnosis was moderately differentiated adrenocortical carcinoma. One month post-surgery and before the start of adjuvant mitotane therapy, FDGPET was performed to exclude further metastases (Fig. 1). This showed increased glucose utilisation in the right paravertebral region with a maximum standard uptake value (SUV) of 6.1. CT (Fig.2) revealed paravertebral soft tissue tumour at the level of L4 with destruction of the adjacent transverse process. Histology following further resection confirmed metastatic adrenal carcinoma. The prognosis in metastatic adrenal cortical carcinoma is very poor [1]. The most common locations for distant metastases are lung, liver and skeleton, but various unusual locations have been reported. Although CT and MRI seem to be sufficient in most patients as the screening method for the most common lung and liver metastases, unusual metastases are very likely to escape the routine diagnostic algorithm [2]. FDG-PET imaging in adults seems to be able to differentiate malignant from benign adrenal lesions [3, 4]. So far, there are no data concerning the staging of adrenocortical carcinomas in children. In our patient FDG-PET was a satisfactory tool for metastasis screening. Primary screening with PET, followed by morphologic imaging with CT or MRI, may be a suitable, cost effective and non-invasive option, especially in children and infants. The estimated effective equivalent dose of 6 mSv corresponds to an intermediate radiation exposure compared with other radiological or nuclear medicine investigations. Since complete resection of the tumour and its metastases seems to be crucial for patient outcome, FDG-PET may have an impact on life expectancy.

Prospective comparison of transcutaneous 3-dimensional US cholangiography, magnetic resonance cholangiography, and direct cholangiography in the evaluation of malignant biliary obstruction

BACKGROUND The purpose of this study was to investigate the ability of transcutaneous three-dimensional US cholangiography to depict the biliary tree in malignant obstruction, compared with that of MRCP and direct cholangiography. METHODS Three-dimensional US and MRCP and direct cholangiography were performed in 40 patients with suspected malignant biliary obstruction. Diagnostic quality of the images, presence, level, and cause of ductal obstruction were assessed in a prospective, blinded fashion. The results were correlated with consensus interpretation (3 investigators), intra-operative findings, and histopathology or clinical follow-up. RESULTS Three-dimensional US produced cholangiographic images of diagnostic quality. The appearance of these images was similar to that of MRCP or ERCP/percutaneous transhepatic cholangiography images. All modalities were highly sensitive in the detection of biliary dilatation. The accuracy of 3-dimensional US, MRCP, and ERCP/percutaneous transhepatic cholangiography in determining the level of obstruction was, respectively, 92%, 95%, and 98%. Transcutaneous 3-dimensional US and MRCP accurately identified the cause of obstruction in, respectively, 90% and 95% of cases. Direct cholangiography revealed the correct diagnosis in 95% of the patients. CONCLUSIONS Three-dimensional US cholangiography is a new, noninvasive method with the capability to produce diagnostic cholangiograms. Three-dimensional US cholangiography may be used increasingly as an initial test to select patients who require further diagnostic evaluation by MRCP or therapeutic ERCP.