CASES

1. CASES DR ASHISH RANA R2 Dept Of Radiodignosis SSGH 23-09-08

2. CASE 1 • 12year old Child with hypertension not responding to antihypertensives. • US abdomen revealed no abnormality. Both kidneys were normal. Doppler US revealed a focal zone of stenosis with peak velocity of 125cm/sec in proximal right renal artery with distally decreased waveforms. • Flush aortography revealed a normal aorta. This was followed by selective renal arteriogram.

3. Selective Rt. renal arteriogram shows focal area of stenosis in proximal third main renal artery with minimal post-stenotic dilatation.

4. Discussion • Systemic hypertension is less common in children (1-5% incidence) than in adults. • Unlike in adults, 70-80% of hypertension in children is due to secondary hypertension, which is often correctable. • Of those children with secondary hypertension, 5-25% have elevated blood pressure with a renovascular etiology.

5. RENAL HYPERTENSION Vascular causes Parenchymal causes Chronic Bilateral Parenchymal Disease Unilateral Parenchymal Disease

6. Causes of unilateral parenchymal disease: (much less common as cause of HT) • Reflux nephropathy • Hydronephrosis • Tumors • Tuberculosis • Renal vein thrombosis

7. Causes of bilateral parenchymal disease: • Reflux nephropathy • Renal vein thrombosis • Hydronephrosis • Chronic glomerulonephritis • Polycystic kidney disease • Radiotherapy

8. Renovascular causes : • Atherosclerosis • Fibromuscular dysplasia • Thrombosis/ embolism • Arteritis- takayasu arteritis, buerger’s disease, polyarteritis nodosa, postradiation • Neurofibromatosis • Vascular trauma • Arterial dissection • Aneurysm of aorta • Extrinsic compression

9. How to investigate a case of renovascular HT? • Clinical suspicion: • Findings highly s/o renovacular disease: • Severe or sudden onset HT esp. in younger patients, • Associated vascular disease • Difficulty in treating HT despite of multidrug therapy • Presence of abdominal bruits

10. Rule out causes other than renovascular one: • Reflux nephropathy • Renal vein thrombosis • Hydronephrosis • Chronic glomerulonephritis • Polycystic kidney disease • Radiotherapy • Tumors • Appropriate investigations to confirm the renovasular etiology & then to come to a final diagnosis.

11. Radiological investigations • Ultrasound: • most readily available tool to rule out renal parenchymal causes of HT like reflux nephropathy, hydronephrosis, polycystic kidney disease, tumors. • In the absence of such causes a significant difference in the size of two kidneys should suggest renovascular etiology. Though a normal appearance of kidneys doesn't rule out the same.

12. Duplex ultrasound: • Diagnosis of RAS is based on findings as: • A peak systolic velocity of >100cm/s in the renal artery. • Renal artery to aorta velocity ratio (RAR)- significant stenosis if the ratio is >3.5 • Parvus tardus waveform in the intrarenal vessels- slope of systolic upstroke <3m/s² & acceleration time>0.07s • Turbulent flow in the post stenotic artery. • Pitfalls: • difficult in obese patients, • failure to visualise midpart of renal artery or to define accessory renal artries & • difficulty in obtaining an accurate angle of insonation.

13. Plasma renin activity: • The baseline plasma renin activity (PRA) is elevated in 50-80% of patients with RVHT. • Measuring the rise in the PRA 1 hour after administering 25-50 mg of captopril can increase the predictive value of PRA. Patients with RAS have an exaggerated increase in PRA (perhaps due to removal of the normal suppressive effect of high angiotensin II levels on renin secretion in the stenotic kidney). • Renal vein renin measurements: • compare renin release from each kidney and are used to predict the potential success of surgical revascularization. • Increased renin secretion in the ischemic kidney as compared to the contralateral kidney, ie, a renal vein renin difference of 1.5, constitutes a positive test result and suggests that revascularization will treat elevated blood pressure successfully.

14. Radionuclide study (captopril challenge test): • Accurate method of identifying patients with functionally significant renovascular HT. It has a sensitivity & specificity of >90% in patients with normal renal function & a normal baseline renogram. • A baseline dynamic renal scan is done using 99m Tc-DTPA or 99m Tc MAG3. • A repaeat study after the administration of 25mg of captopril.

15. ACE positive study: • Fall in total & relative function of affected kidney(>10%) • Delayed time to peak maximum activity (>2min or 40%) • Prolonged intrarenal transit time (>2 min) • In patients with abnormal renal function & abnormal baseline renogram the specificity falls to approx 50%.

16. CT angio / MR angio • Both offer the advantage of being noninvasive. Both have reportedly very high sensitivity & specificity of >95% in the detection of a main RAS of greater than 50%. • The resolution of CT & MR angiography are similar at 2-2.5mm which is sufficient for the main renal arteries as it will provide a clinically useful grading system, resolving stenoses 25% of the renal artery diameter (normal is 8mm).

18. Some common disadvantages are: • Limited resolution so not useful in the assessment of intrarenal vessels & segmenatal arteries. • Accessory arteries <3mm can’t be visualised. • Pressure measurements can’t be done. • Limited use of CT angio in patients with high creatinine. • cost and technique availability. • Gado enhanced MR angio scores slightly above CT angio as it is superior in identification of accessory arteries, no radiation or nephrotoxicity & also multiple projection and temporal precessing can be done.

19. Renal Digital Subtracion Arteriography • Gold standard for the assessment of renovascular disease & RAS. However with the advent of Gad MRA its use is limited prior to angioplasty or stenting. • Flush aortography is usually adequate for the purpose & selective injection into a diseased renal artery is rarely done as in cases of isolated branch stenosis.

20. When it is not possible to assess accurately the degree of severity of RAS, particularly when the stenosis is ostial then also selective ostial injection is done which also enable the measurement of intra-arterial pressures across the lesion.

21. In equivocal cases or in patients with 50% stenoses the stenotic renal artery is catheterized & a selective arteriogram is obtained. • Next the catheter is passed beyond the stenosis to measure the intraarterial pressure to know whether there is a gradient across the lesion. Pressure gradient <15mm of Hg across the stenosis Pressure gradient >15mm of Hg Or 10% of systolic pressure Significant stenosis Insignificant stenosis Angioplasty is done

22. In our case…Selective Rt. renal arteriogram shows focal area of stenosis in proximal third main renal artery with minimal post-stenotic dilatation.

23. There is a long list of renovascular causes… • Atherosclerosis • Fibromuscular dysplasia • Thrombosis/ embolism • Arteritis- takayasu arteritis, buerger’s disease, polyarteritis nodosa, postradiation • Neurofibromatosis • Vascular trauma • Arterial dissection • Aneurysm of aorta

24. Atherosclerosis though produces stenosis of proximal RA similar as in our case but it can be safely excluded considering the age of patient who is a child.

25. Medial fibroplasia subtype of FMD can also be excluded because: • bilateral affection is common, • there is sparing of proximal third main RA, • The string of bead appearance is hallmark.

26. Thrombosis or embolism gives a smooth cutoff sign on angio rather than a focal stricture.

27. Takayasu’s arteritis typically involves ostial part of renal artery, however the involvement of aorta is always present.

28. So considering the age & the location of stenosis the following differentials can be kept: • Fibromuscular dysplasia (intimal fibroplasia subtype) • Neurofibromatosis

29. In Fibromuscular dysplasia (intimal fibroplasia subtype) there is charcteristic unilateral involvement of proximal renal artery which shows smooth symmetrical stenosis with no aortic involvement. • Neurofibromatosis is a rare cause of renal artery stenosis. There is typically a smoothly stenotic stenosis at the orifice of the renal artery with post stenotic dilation. This may be associated with abdominal aortic coarctation or rarely iliac artery stenoses.

30. RAS in Neurofibromatosis: (a) Mid stream aortography shows delayed filling of right intrarenal vessels and a high grade proximal stenosis of the main (upper) right renal artery (arrow). The left renal arteries are unremarkable. (b) Delayed aortography confirms markedly delayed opacification of right intrarenal vasculature (c) Selective renal arteriography shows poststenotic dilatation and mild proximal narrowing of the segmental renal artery.

31. Diagnosis: • Fibromuscular dysplasia (intimal fibroplasia subtype)

32. Is it important to differentiate between the medial fibroplasia & intimal fibroplasia subtype? • This is important by the view of treatment as medial fibroplasia is non progressive & the beaded appearance dialtes easily at low pressure with excellent long term results. While other subtypes are though rare but are progressive & have smooth stenosis which may not dilate satisfactorily so that stenting is necessary.

33. CASE 2 A 35 year-old man, after an accident, becomes confused and disoriented over 24 hours after hospitalization. Devoloped extensive cutaneous petechiae Skeletal survey- right femoral fracture.

34. T2-weighted [T2W] and fluid-attenuated inversion recovery [FLAIR] MR images show multifocal areas of hyperintensity in the periventricular, deep, and subcortical white matter bilaterally T2WI FLAIR

35. Some of these same areas demonstrate restricted diffusion on diffusion-weighted imaging [DWI] and its corresponding apparent diffusion coefficient map [ADC] , consistent with cytotoxic edema in these areas. ADC DWI

36. T2-weighted gradient-echo [T2 GRE] MR imaging shows multiple hypointense punctate susceptibility artifacts diffusely distributed throughout the periventricular, deep, and subcortical white matter bilaterally, consistent with petechial hemorrhage in these areas T2 GRE

37. D/D CEREBRAL FAT EMBOLISM DIFFUSE AXONAL INJURY

38. CEREBRAL FAT EMBOLISM Usually associated with long bone fractures Typically occurring within several hours to days of injury. Hypoxia, mental status change, and cutaneous petechiae are the main clinical diagnostic criteria of fat embolism syndrome (FES) Lesions gradually disappear within a few weeks to months. In CFE, T2W and FLAIR images generally show small scattered hyperintense lesions predominantly in the periventricular, deep, and subcortical white matter, which are due to vasogenic edema and perivascular leakage of blood. Consequently, the lesions enhance with Gd-contrast.

39. CFE - FLAIR MR image of the brain show multiple focal lesions in the periventricular, deep, and subcortical white matter.

40. CFE - Contrast-enhanced MR image of the brain show focal enhancement in many of the white matter lesions.

41. CFE - T2*-weighted gradient-echo MR image of the brain show a single focus of susceptibility (arrow ) in the left frontal white matter. This finding suggests a preexisting focus of hemorrhage

42. DIFFUSE AXONAL INJURY Due to mechanical shearing and disruption of axons following sudden traumatic deceleration Unconscious from the moment of injury with no significant improvement in conscious level over time . T2W and FLAIR images demonstrate hyperintense lesions at characteristic locations along gray-white matter interfaces at sites of maximum shear strain – cerebral subcortical regions (especially frontal and temporal lobes), genu and splenium of the corpus callosum, dorsolateral brain stem, superior cerebellar peduncle, and internal capsule. Lesions are typically oriented with their long axis parallel to fiber bundle directions. Some of these lesions may appear hyperintense on DWI, either due to T2 shine-through or because of cellular death and myelin disruption. Associated petechial hemorrhage may or may not be present but appear more conspicuous on T2* GRE images.

43. DAI : The axial gradient-echo (FLASH) sequence shows punctate areas of signal loss at the grey-white interface in the frontal lobes

44. DAI : A, Transverse GRE , B, SW MR images. Small hemorrhagic shearing injuries (arrows in B), such as those commonly seen in the subcortical junction of gray and white matter, were often seen only on the SW MR images.

45. So, in our case,

46. So , The diagnosis in our case is CEREBRAL FAT EMBOLISM

47. CASE 3 • A 75 year old female presented with c/o retrosternal pain with reflux.

49. Axial CT scan of the thorax in a 75-year-old woman shows a retrocardiac mediastinal mass with a fluid level due to a hiatal hernia

50. DIAGNOSIS- HIATAL HERNIA