Pattern recognition system for focal liver lesions using "crisp" and "fuzzy" classifiers.

RATIONALE AND OBJECTIVES: To determine the diagnostic performance of an artificial intelligence system for classification of focal liver lesions, in comparison to human observers. METHODS: One hundred forty-three focal hepatic lesions were evaluated with dynamic computed tomography. The study comprised 59 hemangiomas, 24 other benign lesions (focal nodular hyperplasia, adenoma), and 60 malignant liver lesions (18 primary, 42 secondary). All lesions but the hemangiomas were histologically examined by needle biopsy. For delineation of the lesion, a region of interest was defined interactively. The pattern recognition was performed in two steps with initial extraction of textural features: training of a classifier and classification of the lesions. The accuracy of classification of hepatic lesions into three groups (hemangioma, other benign processes, malignant lesions) was tested. The results were compared with those achieved by human observers using receiver operating characteristic statistical analysis. RESULTS: The accuracy (total rate of correct diagnoses) was 90.2%. False classifications were found owing to small size, weak contrast enhancement after bolus injection, respiratory movement, and atypical morphology of the lesion. The area under the receiver operating characteristic curve was not significantly different for computer and human observers. CONCLUSIONS: The system demonstrated a diagnostic accuracy comparable to human observers. Further improvement with increasing numbers of typical computed tomographic series for training of the classifier can be expected.

[CT-guided course-punch biopsy of the adrenals. The indications, technic and results]. / CT-gesteuerte Grobstanzbiopsie der Nebennieren. Indikationen, Technik und Ergebnisse.

Adrenal lesions exceeding 1.5 cm diameter were biopsied with a Tru-Cut needle (G 14) under CT guidance for histologic evaluation in 61 patients. Using CT for guidance, special techniques for safe access to the adrenals are described. Large-bore biopsy yielded a sensitivity of 100% and a specificity of 97.4%. Diagnostic accuracy was 98.3%. No significant complications occurred. In comparison to the results of FNA reported in the literature, large-bore biopsy of adrenal lesions improves the rate of adequate material and the histopathologic differentiation without increase of complications.

[CT-guided Tru Cut biopsy of solid pelvic space-occupying lesions. The indications, technic and results]. / CT-gesteuerte Tru-Cut-Biopsie soldier pelviner Raumforderungen. Indikationen, Technik und Ergebnisse.

Solid lesions in different localisations of the pelvis were biopsied with a large-bore Tru-Cut cannula (G 14) in 88 patients under computed tomographic guidance. Special techniques for safe access to pelvic lesions are described. Indications for biopsy were suspected extraluminal tumour recurrence (n = 49), masses outside the pelvic organs in the absence of a known pelvic primary (n = 21) and in the presence of a known pelvic primary (n = 10). In 8 cases, lesions situated within pelvic organs were punctured. Without any repeat biopsy, accuracy reached 96.6%, sensitivity was 95.2% and specificity was 100%. In comparison to the results of FNA reported in the literature diagnostic accuracy can be improved upon by using large-bore biopsy. No complications occurred.

[The computed tomography of malignant otitis externa]. / Computertomographie der malignen Otitis externa.

Computed tomography was performed preoperatively in 20 patients suffering from malignant external otitis. The CT findings were nearly completely confirmed by the intraoperative findings. A circumscribed or diffuse thickening of the cartilaginous wall of the external auditory canal and an inflammatory infiltration of the subtemporal fossa are, in combination, most suspicious signs of malignant external otitis. Computed tomography enables detailed information on the extension of the pneumatic system and the grade of involvement of bones and soft tissues in malignant external otitis. A modified classification of malignant external otitis based on computed tomographic findings is proposed.

[The accuracy of plain-film radiology in demonstrating the shadows of the pneumatic spaces of the skull--a comparison with computed tomography]. / Treffsicherheit der Nativradiologie im Nachweis von Verschattungen der pneumatisierten Räume des Schädels--Vergleich mit der Computertomographie.

The accuracy of plain-film radiography in the diagnosis of opacities of the pneumatic system of the skull was evaluated in 302 patients in comparison with computed tomography. Plain films were performed using standard projections (Schüller, Stenvers, NNH o.n., paranasal sinus). Concerning the paranasal sinuses sensitivity of plain film radiography ranged from 36.7 to 66.4% depending on localisation. In the mastoid, a sensitivity of only 35% was found. Specificity was high (90% and over) with the exception of the maxillary sinus (82%). More sensitive, noninvasive diagnostic imaging techniques are indicated in the following conditions: therapy-refractory opacification of one sinus, indeterminate otological symptoms in the presence of a low pneumatized mastoid, and definitive exclusion of infectious foci in the pneumatic system of the skull.

[CT-guided large-bore biopsy of solid non-organ-bound space-occupying lesions in the retroperitoneum]. / CT-gesteuerte Grobstanzbiopsie solider nicht-organgebundener Raumforderungen im Retroperitoneum.

Seventy-eight solid, non-organic retroperitoneal tumours were biopsied with a 14-gauge Tru-Cut needle in 73 consecutive patients with the exception of one. Adequate material was not obtained in only one patient with the primary known (1.3%). In the adequate material (98.7%), the dignity of all lesions was accurately determined and 93.1% of lesions were accurately classified. Typing accuracy reached 100% in histologically known primaries (n = 31) and 87.8% in histologically unknown primaries (n = 41). A hypertensive crisis and a small haematoma following biopsy of an inadvertent extra-adrenal phaeochromocytoma was the single complication found in this series. An arterial bleeding following biopsy was prophylactically embolised through the biopsy needle. CT-guided large-bore biopsy of solid non-organic retroperitoneal tumours is a safe, non-invasive procedure with a high diagnostic yield that obviates the need for open diagnostic procedures in a large number of cases.

[Percutaneous CT-controlled cutting-needle biopsy of diffuse interstitial and alveolar lung diseases--the technic and results]. / Perkutane CT-kontrollierte Schneidbiopsie diffuser interstitieller und alveolärer Lungenerkrankungen--Technik und Ergebnisse.

Twenty-three patients underwent CT-guided large-bore biopsy of diffuse lung disease of clinically and radiologically indeterminate etiology. The procedure was preceded by negative transbronchial biopsy in 20 cases. CT-guided biopsies were performed with a 14-gauge Trucut-needle. Obtaining at least 3 specimens of different parts of the diseased area, a correct histologic diagnosis was achieved in all cases. The size of the histologic specimens (mean: 5-6 mm) exceeded that of the specimens obtained by transbronchial biopsy as reported in the literature. Two major complications occurred and included a rapidly developing tension pneumothorax treated by a small-bore catheter and one self-limited hemoptysis. Major advantages of percutaneous CT-guided biopsy are the nonsuperimposed and very sensitive imaging of lung alterations in diffuse lung diseases that allows evidence of adjacent less and more involved areas accessible by one biopsy approach. CT-guided large-bore biopsy with a cutting needle seems to be a very promising, accurate method in the pathomorphologic work-up of diffuse lung diseases rendering open biopsy unnecessary in many cases.

[Computer tomography of malignant renal lymphomas]. / Computertomographie renaler maligner Lymphome.

The pre- and postcontrast CT findings of 11 patients with lymphoma involving the kidneys are described. In all cases the renal lesions showed low attenuation values after bolusinjection. In contrary to the literature renal lymphoma might present different attenuation values in the non-contrast enhanced CT scan. The density varies from hypo- to iso- and hyperdens. A bolusinjection of contrast media should be performed to depict even greater nodules.

[Lacunar infarcts in computerized tomography. Angiographic findings and differential diagnostic viewpoints]. / Lakunäre Infarkte im Computertomogramm Angiographische Befunde und differentialdiagnostische Geischtspunkte.

Eighty-four patients with ischaemic cerebral lesions are described, in whom no lesion of the cortex could be demonstrated by CT. Lacunar lesions of the basal ganglia up to 2 cm. usually fail to show any angiographic findings. The clinical prognosis in these cases is favourable. Lesions larger than 2 cm. are usually due to haemodynamically significant stenoses. Prognosis depends not only on the size of the lesion, but also on its localisation, particularly its relationship to the motor radiation. The indications for angiography and therapy depend in part on a proper evaluation of the differential diagnosis of the lesions.

[The percutaneous removal of osteoid osteomas via CT-guided drilling]. / Perkutane Entfernung von Osteoidosteomen durch CT-kontrollierte Bohrung.

Osteoid osteomas were removed by CT-guided core drill excision of the nidus in 4 patients. All osteoid osteomas were located in the lower extremity and included cortical lesions in the femur (n = 2), and the tibia (n = 1) and one spongious lesion in the navicular bone of the foot. Nidus diameter ranged from 2 to 3 mm. The patients were discharged after the procedure same day or next day depending on the kind of anaesthesia performed. Follow-up periods ranged from 6 to 56 months and revealed no signs of recidivation. CT-guided core-drill excision of the nidus seems to be a very promising alternative to surgical procedures because of its high cost-effectiveness and minimal invasiveness.

[Therapy of intestinal bleeding by the intra-arterial injection of a synthetic vasopressin derivative]. / Therapie der intestinalen Blutung mit intraarterieller Injektion eines synthetischen Vasopressinderivates.

The synthetic drug Ornipressin was injected through a 3-French catheter introduced into the superior or inferior mesenteric artery by a coaxial method in nine patients with massive bleeding from the colon. In all patients the bleeding was stopped. In one female patient with a tumour, bleeding recurred, but was stopped by embolisation treatment. There were no complications needing treatment. As a method of treatment for bleeding from diverticula, the following procedure is recommended: an attempt should be made to stop bleeding by injecting vasopressin, or one of its derivatives and the use of a 3-French catheter by a co-axial method is advantageous. If vasopressin is contra-indicated, or is unsuccessful, catheter embolisation is recommended.

[Confirmation of the T classification of bladder tumors by transcutaneous sonography, intra-vesical sonography and computer tomography]. / Sicherung der T-Klassifikation von Harnblasentumoren durch transkutane Sonographie, intravesikale Sonographie und Computertomographie.

Forty-two patients with carcinoma of the bladder were examined by intravesical and transcutaneous sonography, as well as by computed tomography, in order to determine their T-classification. None of these methods permitted a distinction between T2 and T3a as recommended by the UICC (1978), with any degree of certainty. Intravesical sonography is best for defining superficial tumours. Transcutaneous sonography has proved satisfactory for differentiating muscle-infiltrating from extravesical tumours. Computed tomography shows infiltration of tumour into the perivesical fat and into neighbouring organs; infiltration of tumour into the prostate cannot always be demonstrated.

[Changes in the mucosal pattern of the colon in the early stages of ulcerative and granulomatous colitis (author's transl)]. / Feinreliefveränderungen des Kolons im Frühstadium der Colitis ulcerosa und Colitis granulomatosa.

By paying attention to the detailed relief pattern of the colonic mucosa on double contrast films, it is possible to recognise the early changes due to inflammatory colonic disease. The presence of a granular appearance suggests an early stage of ulcerative colitis; multiple small flecks of contrast, sometimes surrounded by a clear area, indicate aphthous ulcers in an early stage of Crohn's disease.

[Dynamic inversion recovery snapshot FLASH MRT of focal nodular hyperplasia of the liver]. / Dynamische Inversion-Recovery-Snapshot-FLASH-MRT der fokal nodulären Hyperplasie der Leber.

11 lesions of focal nodular hyperplasia (FNH) in 6 patients were studied by means of dynamic snapshot-FLASH MRI before and after bolus injection of Gd-DTPA. In addition, plain snapshot-FLASH images were compared with T1- and T2-weighted spin-echo (SE) images and with T1-weighted breathhold-FLASH images. Highest FNH-liver signal-difference-to-noise ratios were obtained with snapshot-FLASH followed by T2-SE. In all patients contrast-enhanced serial snapshot-FLASH demonstrated reliably the typical haemodynamic appearance of FNH known from dynamic computed tomography. Because of its high intrinsic lesion-liver contrast and high time-resolution dynamic snapshot-FLASH MRI may facilitate differential diagnosis of hepatic tumours.

[Ultrafast pelvimetry using Snapshot-FLASH-MRT--a comparison with the Spinecho and FLASH techniques]. / Ultraschnelle Pelvimetrie mittels Snapshot-FLASH-MRT--Vergleich mit der Spinecho- und FLASH-Technik.

Pelvimetry by means of snapshot-FLASH-MRI was carried out during the last trimester in 20 pregnant women. In 10 cases the results were compared with conventional spin-echo and FLASH-MRI. Snapshot-FLASH-MRI resulted in identical measurements but in addition provided images free from motion artifacts with good contrast of bone and soft tissue structures. The reduction in acquisition time resulted in pelvimetry in a few seconds. The total examination time and comfort for the patient were thereby improved.

[Contrast-enhanced MRT of malignant melanoma of the uvea]. / Kontrastmittelunterstützte MRT maligner Aderhautmelanome.

Twenty-one patients with malignant melanoma of the uvea or iris, some with intra-ocular bleeding, were examined by MRT before and after the administration of Gd/DTPA. In 13 patients, several examinations were performed over a period of 1.5 to 20 months after irradiation of the melanoma. After Gd-DTPA there was an average increase of 13% in the signal intensity from all non-irradiated melanomas (17 cases). Three months following radiation therapy, there was an average increase in signal intensity after Gd-DTPA of 65.7%, and after seven months of 100%. Amelanotic melanomas (two cases) showed a primary increase in intensity of 100%. Two melanomas of the iris were demonstrated by sonography; of these, only one could be shown with certainty by MRT. Small tumours and tumour residues after irradiation were better defined after contrast. In the presence of suspected intra-ocular bleeding, the examination should always be performed after the administration of Gd-DTPA.

[The diagnosis of focal liver lesions by the texture analysis of dynamic computed tomograms]. / Diagnostik fokaler Leberläsionen durch Texturanalyse von dynamischen Computertomogrammen.

Characterisation of focal liver lesions on computed tomography (CT) depends on correct interpretation of morphology and dynamic changes during bolus injection of contrast medium. The aim of this study was to develop a texture analysis concept for computer based interpretation of dynamic CT images. 148 focal liver lesions were investigated by serial CT. The study comprised 61 haemangiomas, 25 other benign lesions (FNH/adenomas) and 62 malignant lesions (primary or secondary). FNH, adenomas and malignant lesions were histologically proven. Diameter was 8-145 mm (mean 31 mm). Regions of interest were interactively defined. After extraction of characteristic textural features, a pattern classifier was trained. All CT series were evaluated using the "leaving-one-out" method. 134 of the 148 lesions were correctly classified (positive predictive value 0.9). Sensitivity for the presence of malignancy was 0.93 (80/86), specificity was 0.9 (56/62). False classification of a lesion was found to depend strongly on the quality of the examination (bolus intensity, positional change of the lesion due to respiratory movements).

[MR tomography of colorectal diseases with a negative rectal contrast medium]. / MR-Tomographie kolorektaler Erkrankungen mit negativem rektalen Kontrastmittel.

The potential of the generic kaopectate (Upjohn) as a negative rectal contrast agent in MR imaging was investigated in the assessment of colorectal disease. 45 MR examinations in patients with colorectal disease (colorectal carcinoma 25 patients, inflammatory disease 12 patients, miscellaneous disorders of the colon 8 patients) were evaluated. All examinations were performed with T1 and T2 weighted SE sequences after rectal application of kaopectate. Gd-DTPA enhanced T1 SE sequences were obtained as well. Kaopectate revealed a signal void of the lumen of the large intestine in T1 and T2 weighted SE sequences. Intravenous administration of Gd-DTPA enabled good differentiation of contrast-enhanced malignant or inflammatory tissue and the low signal lumen of the bowels. No side effects were noted.

[Arterial DSA using CO2 as a contrast medium: improvement of picture quality using a novel gas injector in an animal experiment]. / Arterielle DSA mit CO2 als Kontrastmittel: Verbesserung der Bildqualität mit einem neuartigen Gasinjektor im Tierexperiment.

The use of CO2 as contrast medium for DSA requires accurate and reproducible doses of the gas. This cannot be achieved by manual injection or by using injectors designed for liquid contrast media. For this reason a new gas injector has been developed which meets these requirements despite the compressibility of gas. The suitability and ease of use of the injector has been confirmed in experiments on 15 dogs. At the same time optimal volumes for different vessels with varying diameters have been determined. It has been shown that the injection parameters (gas speed and volume) in small vessels up 10 mm. diameter are not critical. With increasing vessel diameter accurate gas dose becomes important in order to perform optimal angiograms safely.

Cytologic versus histologic evaluation of needle biopsy of the lung, hilum and mediastinum. Sensitivity, specificity and typing accuracy.

Fine needle aspiration biopsy (FNAB) and punch biopsy (PB) are reliable methods of establishing a morphologic diagnosis in thoracic lesions. However, some reservations exist concerning the diagnostic accuracy of and indications for both methods. Therefore, we evaluated the sensitivity, specificity, typing accuracy and complication rates of both methods. We present a six-year experience with 501 thoracic FNABs and PBs in 482 patients. To examine site-specific differences, we evaluated three different compartments: lung, mediastinum and hilum. In 457 cases the final outcome was known for evaluating the accuracy of the cytologic or histologic diagnoses. FNAB was used most often in lung (81.8%) and hilar lesions (87.3%), whereas PB was used mostly in mediastinal (67.9%) and pleural lesions or if a mesenchymal lesion was suggested radiologically but never in foci below 20 mm in diameter. Our complication rate was 21.3% for FNAB and 4.6% for PB. The most frequent complications were pneumothorax, one hematothorax and intercostal neuralgia. The overall sensitivities of the biopsy methods were equal (FNAB, 98.4%; PB, 98%), but the typing accuracy was better for PB than FNAB (87.2% vs. 83.5%). In the hilum the sensitivities of FNAB and PB were 94.6% and 85.7%, respectively, and for the lungs, 99% and 98.2%. In the mediastinum the sensitivity was 100% for both methods. There were false-positive diagnoses in 5% with FNAB of the lung due to misinterpretation of regenerating epithelium and hamartochondroma and a 0.1% rate of false-negative diagnoses as a result of misplacement of the cannula, leading to inflammation, infarction or scarring. Our data indicate that FNAB is the method of choice in pulmonary and hilar lesions because of the similar diagnostic accuracy. Mediastinal and pleural lesions and presumed mesenchymal tumors should be sampled with PB because the typing accuracy of FNAB is insufficient in these cases.